CHAPTER 16

LAND MAMMALS

GÜNTER TEMBROCK

The specific nervous organization of mammals, in connection with highly developed motor patterns, involves a rich repertoire of “nonritualized” actions. The behavior patterns are tied to nonritualized structures, and they are performed without interanimal transmission of information. These patterns include the following groups of functions: respiration, food gathering, defecation and urination, rest and sleep, inquiry (orientation in space and time), protection, and defense. There are a few nonritualized actions comprehended by the group of functions, reproduction; however, in mammals, reproduction functions always are connected with information transmission which can appear also in the framework of other groups of functions, but in these it has only secondary importance.

The transmission of information presumes signal actions and/or signal structures which are behavior patterns or properties that have experienced a change of function during phylogenesis and now serve to transmit information. Therefore, the cooperation of the reception system of a receiver is important for its evolution (Sebeok, 1965; Tembrock, 1967; Wickler, 1961). The process of the formation of systems in which information is transmitted by means of a change in the functions of already existing systems is termed ritualization by Huxley (1923) (see also Marler, 1961; Sebeok, 1965; Tembrock, 1967 Wickler, 1961). Receptors which determine this ritualization in mammals include: chemoreceptors (sense of smell), mechanical receptors (particularly sense of hearing), and photoreceptors (sense of sight). The motor patterns of mammals have experienced a differentiation during evolution which, above all, is marked by the development of pyramidal tracks. The central nervous control has led, in this connection, to a “relative coordination” in which the several patterns of behavior (“subprograms”) may be combined alternatively, and often individual experiences will fix the sets of behavior (syndromes of behavior patterns) (Eibl-Eibesfeldt, 1963; Tembrock, 1964). Besides, there is also an “acquired coordination,” the adaptation of which is either fixed genetically or also determined by experiences (Eibl-Eibesfeldt, 1963). The innate coordinations in many mammals are reduced to small units (low level of integration); therefore, the scope of individual adaptability (voluntary movements) is increased (Eibl-Eibesfeldt, 1963). The gradually developing freedom of the motor ability of the hands may be followed in Glires as well as in Primates. Evidently this trend of evolution is connected with the increasing elaboration of play behavior (Eibl-Eibesfeldt, 1963; Tembrock, 1964). At the same time, it favors ritualization, e.g., by loss of coordination, by exaggeration of an action as in mime, by superposition, blending of motivation; these can also include the autonomic system (piloerection, respiration, glandular secretions). The dominant receptor systems determine in each case the development of the signals; in land mammals, chemoreception prevails originally, later on, phonoreception, and then photoreception. Yet, naturally, there are numerous overlaps, as, in principle, all of the three systems are always available.

The dominance of chemoreception may be explained by the fact that during the earliest evolutionary development of mammals, during the Mesozoic, reptiles still dominated the large territories to such an extent that the development of optically effective signal systems in mammals was checked by virtue of the fact that these systems were dominant in reptiles. In these, accordingly, skin glands serve but rarely for information transmission, whereas in land mammals just these developed, under this pressure of selection, particularly, by a change of function in the rudimentary sweat and sebaceous glands. According to Schaffer (1940), the sebaceous glands must be considered to be the more primitive elements of the skin-gland organs. Thus, one may derive from this type, by change of function (as “signal structures”), polyptychous glands of numerous mammals (for instance Arvicola, Cricetus, Cavia, Galemys, Lemmus, Dasyurus, Hydrochoerus, Oryctolagus, Rhinolophus, Vulpes, Viverridae, Felis, Capreolus, Rupicapra). So far, only a few chemical analyses of odor secretions in mammals have been made (Lederer, 1950; Magnen, 1963; Parkes and Bruce, 1961). In the castoreum of the beaver alone, about fortyfive different chemical substances have been found (Lederer, 1950). Thus, the change of concentration of single ingredients of such a mixture may transmit specific information; also, the synergistic effects of different odor glands can produce specific results (Wilson and Bossert, 1963). Intraspecifically effective scents may be summarized as pheromones or homotelergones; interspecific ones as heterotelergones (Kirschenblatt, 1962). Odors may, intraspecifically, pass on the following information: conspecific, individual, sex, tribe, age, and physiological status (Schultze-Westrum, 1965; Wilson and Bossert, 1963). In marking behavior one may distinguish self-markings, partner markings, and territory markings. A chemical signal may release behavior immediately: either as a “releaser-effect” or, metabolically, as a “primer-effect” (Wilson and Bossert, 1963).

The second receptor system which might have gained in importance even during the Mesozoic is the acoustic system. To the first, rather small, mammals inhabiting places difficult to survey and control it might have been advantageous for close contact because, compared with the chemical transmission of information, acoustic transmission is more rapid and therefore might have been further developed. Sounds were produced mechanically (“instrumentally,” i.e., sounds of teeth or steps), but sounds produced by respiration also became functional by means of further development of the larynx. Two functional systems, defense sounds and sounds of “self-advertisement,” probably originated first. The first group of sounds is related to specific defensive behavior and serves to increase the distance between the emitter and the receiver (Tembrock, 1959; Thomson and Owen, 1964). The second group of sounds is significant particularly in small mammals whose normal reaction to stronger sounds in the environment is flight; they “neutralize” this behavior by self-advertisement to the conspecific. This type of sound (self-advertisement) is the most primitive transmission of information-serving communication; when it is produced by both emitter and receiver, “voice contact” will develop out of it. From this may be derived the most diverse specialized patterns of acoustic information transmission (and ritualization), but also, as special cases, danger signals and emergency calls and “sounds of loneliness” as well. Mammals are able to transmit the following information acoustically: species, sex, individuality, age, physiological status, motivation of behavior, space, and time. Rarely one single species can transmit all these patterns of information acoustically. Particularly in the transmission of information about behavior motivation there is a wide spectrum of possibilities, which allows for the realization of fine shades of meaning in some species, whereas in others only the principal function systems are affected.

Moreover, one must realize that in every case nonacoustic systems of transmitting information are also available. One must include here the second type of mechanoreception, the sense of touch, responding to tactile stimuli. Physical contact is necessary; hence the development of a tactile means of communications is most likely primary only in reproduction behavior (including the rearing of young). Its primary function is, of course, the transmission of tactile external stimuli in spatial orientation (nonritualized action). Derived from the transmission of information through tactile stimuli in reproduction are similar patterns of communication in the framework of other groups of functions (“social behavior”), especially in rest and sleep and in comfort movements (social grooming).

Finally, it has yet been little studied to what extent thermic impulses serve the transmission of information, but in the rearing of the young (mother-child behavior and sibling behavior) these stimuli form an important complex in many mammals (Rheingold, 1963). Yet, since only nonspecific information may be transmitted (presence of a warm-blooded creature of a specific body temperature), it is inconceivable that this system of transmission be efficient except in conjunction with other systems of information.

The third receptor system examined, the optical means of information transmission, includes ritualizations concerned primarily with behavior, but also with structures (signal structures), for instance, conspicuous color patterns which become noticeable through special movements. Autonomically controlled areas (fur, raising of hair, display of light parts of fur, etc.) may be included also, along with facial expressions and the concomitant muscle derivations of the fascialis sphere and the platysma. It seems that one can distinguish generally between two main groups of optically effective systems: frontal systems and lateral systems. The first group appears partieularly in species with frontally placed eyes, the second group in those species with more laterally placed eyes. Caudal systems (tail, back, in part the anogenital regions) have developed as optically effective information transmitters, chiefly in connection with reproduction, rearing of young, and flight behavior. This also indicates, in each given case, the relative position and direction of effects of the optical transmission systems which are codetermined by special functional conditions. In this respect, this group of information-transmitting systems differs from the two mentioned before: the signal structures must be arranged in such a way that they can be optimally seen by the receiver (recipient) during the demonstration of the behavior belonging to the signal structure.

During the phylogenesis of mammals, this system has developed last of all for the reasons already mentioned. It has been favored by increasing physical growth. The time of the daily phase of activity and the nature of the territory have also had significant influence on the development of optically effective signal systems. They have developed particularly in day animals which live in open grounds or in Carnivora), so that even minimal changes of behavior can have an species which live in close social contact (for instance Primates, some optical effect (facial expression!). As the primary weapons of mammals are the teeth, the face became the primary center of attention, and several optically effective signal systems have developed in this part of the head region. Likewise, several secondary signal structures, for instance, antlers and horns which originated there, have then also become weapons. According to this derivation in which the optically effective signal systems on the heads of mammals (signal actions and signal structures) are derived from the teeth having primary significance, the information transmitted by means of these systems concerns the disposition of motivation. Other information (concerning species, sex, individual age, physiological status), if at all optically transmitted, is arranged over the whole body, frontally or laterally; for instance, changes in color and shape. In the following survey a view of communciation patterns in the main groups of land mammals, in each case arranged according to the three main methods of information transmission, is presented in as much detail as the still very insufficient knowledge allows.

MONOTREMATA

Very little is known about communication in Monotremata.

Chemical Transmission of Information

Echidna possesses a fine sense of smell. The lobi olfactorii are well developed. Echidna aculeata Shaw leaves odor marks with the extended cloaca for marking the territory (Dobroruka, 1960; Hediger and Kummer, 1961). One may suppose that, by specific odor stimuli, traces will be marked, and a chemical orientation toward the partner will become possible across greater distances. Here these glands are sebaceous glands (Schaffer, 1940). The secretion has an odor which is also distinctly perceptible by human beings. Since Echidna come into intraspecific contact only during mating, more differentiated patterns of communication are lacking. Analogous facts seem to apply to the platypus (Crandall, 1958). Ornithorhynchus also has glands which give off a pervasive odor.

Mechanical Transmission of Information

Acoustic transmission of information has not yet been found in this group of mammals; platypus seems to have only one sound of defense at his disposal, Echidna utters rhythmic sounds of respiration, about the function of which nothing is known (Hediger and Kummer, 1961). Yet it is certain that the Monotremata possess a fine sense of hearing. Probably, it serves mainly in food gathering. Tactile transmission of information is most probable in connection with courtship display and the rearing of the young; details are not known. In Ornithorhynchus the touch of the flattened tail of the female by the “bill” of the male seems to be an important stimulus for the beginning of copulation (Crandall, 1958).

Optical Transmission of Information

The Monotremata probably are active only at dusk or at night. Their eyes are very poorly developed, and there are no indications of optical communication mechanisms.

MARSUPIALIA

This voluminous order, differentiated in numerous and very different forms, contains about 80 genera with more than 250 species (Walker, 1964), which often show conspicuous convergences to groups of Placentalia.

Chemical Transmission of Information

This mode of transmission of information commonly dominates in the dusk or night-active species. Aside from two anal glands, there are numerous types of skin glands (Schaffer, 1940), so that some species, in many cases the males in particular, exhibit an odor which is conspicuous even to man. A frontal and a sternal gland as well as glands in the anal region and in the pouch have developed in Petaurus. Chemical signaling here takes place by self, mate, or territory marking; we can distinguish six modes of territorial marking as well as a special behavior for active odor transmission to the conspecific. The odor materials of the sternal gland, frontal gland, and the anal glands of the males differ. The males individually produce differentiated odors in these glands, whereas the females individually possess differentiated odors in their pouches. As individual odors they may release personal recognition, but they may also function as tribe odors, in which case they release anonymous recognition of tribe affiliation. Thus, nestlings first learn to recognize their tribe members (except their own mother) in this anonymous fashion. Chemical signaling also influences the construction of an order of rank. Furthermore, chemical information about affiliation of species and about sex as well as about physiological status has been demonstrated for Petaurus. Urine marking can be found in Petaurus, where leaves lining the burrow are drenched with urine, giving a musky odor (Schultze-Westrum, 1965). This odor is especially conspicuous in Hypsiprymnodon moschatus Ramsey (Walker, 1964). Pseudocheirus marks its courses with urine (Thomson and Owen, 1964). Trichosurus vulpecula Kerr possesses a large sternal region of glands. By straddling the forelegs and bending the head backward, it can rub its breast against the substrate; in so doing the secretion is given off. Glands on the soles (plantar organs) also serve for chemical signaling. In kangaroos scarcely anything is known about the marking of territory, yet in Dendrolagus a good sense of smell has been shown, and the possibility of chemical signaling of tribe affiliation seems to be likely (Schneider, 1954). Territories have been described for different species of kangaroos (Hediger, 1958, Immelmann, 1965; Sharman and Pilton, 1964).

Mechanical Transmission of Information

Acoustic signaling is widespread in bipedally moving species, taking the form of drumming with the hind legs (danger signal). Sounds in general are not very common and are observed most frequently in defensive behavior; frequently these are sounds which have developed from voiced respiration sounds (Dendrolagus, Schneider, 1954); young animals also utter “calls of loneliness” (Macropus, Dendrolag us). As the Marsupialia in most cases possess well-developed external ears and are predominantly dark-active, one has to attribute high significance to the sense of hearing, at the very least in terms of orientation, food gathering, and defensive behavior; yet more detailed studies of acoustic modes of communication have not yet been made. In Trichosurus vulpecula Kerr the following order of precedence (rank) of senses is given: hearing, touch, smell, vision (Walker, 1964).

Optical Transmission of Information

Generally, in Marsupialia, eyesight is very little developed, yet some dusk-living forms possess conspicuously large eyes (Marmosa, Dromiciops, Sminthopsis, Dasyurides, Antechinomys, many Phalangeridae). Eyesight seems to serve above all for food gathering. However, there are a few signal structures, among them the red powdering of the males of Macropus (Megaleia) ruf us (DESM). An optically effective signal action is probably the erect sitting up in many kangaroo species, a posture which releases agonistic behavior (Fig. 1). Likewise, a human being walking upright may evoke aggressions which cease when he bends down (Hediger, 1961).

INSECTIVORA

To the Insectivora belong 8 families with about 63 genera; nearly 300 species have been described so far. Their modes of communication are still very insufficiently known; the often tiny body and secret way of life of these preponderantly dark-active animals render observation very difficult. Echolocation has been supposed for Soricidae and Tenrecidae (Gould et al., 1964; Gould 1965). Chemical and acoustic methods of information transmission certainly dominate over optical ones.

Chemical Transmission of Information

Among Insectivora, odor glands are widespread, and it is very probable that the territories are marked by odor substances. In Soricidae there are flank glands, the secretions of which have a musky odor and which are more developed in males (Herter, 1957). Blarina possesses, besides the paired flank glands, a third unpaired abdominal gland (an enlarged sebaceous gland) which is also more developed in the male; district (territory) marking is the supposed function (Pearson, 1946). It is known that the Crocidura species leave bales of feces on certain vertical parts of structure, and thereby probably mark (Crowcroft, 1955; Herter, 1957); in Crocidura russula (Herrn.) this occurs mostly five to seven centimeters above the ground. Sorex araneus L. also seems to have deposits of feces in the territory. Different Sorex species and Neomys defecate regularly a certain distance from the nest (Crowcroft, 1955). Also, Sorex vagrans (Eisenberg, 1964), Potamogale velox Du Chaillu and Erinaceus europaeus L. have special deposits of feces in the territory. It is reported that Echinops telfairi Martin salivates on marking places, then, with its hand, scratches first them and then its own body. This behavior may show connections with the self-salivation of hedgehogs (Eibl-Eibesfeldt, 1965; Herter, 1957). The significance of back lubrication in Petrodomus is still unknown.

The “nest-odor” seems to be a significant factor for the marking of tribes. In the “caravans” of Crocidura, the young lock their teeth into the back end of a tribe member, so that usually the mother drags a chain of young in which certain external stimulations release the formation of a “caravan.” The motion is highly coordinated, so that the “caravan” gives the impression of “one single being.” Very exact transmission of signals coordinates the moving, turning, and sudden stopping of the whole formation (Herter, 1957).

For Sorex vagrans, ten types of behavior with intraspecific significance have been described: (1) naso-nasal, (2) naso-anal, (3) nose to body, (4) chase, (5) flight, (6) upright (one or both animals rear, generally squealing, while warding with the forepaws), (7) approach (without contact), (8) moving away, (9) following, (10) flight. Two tail postures were noted. In the first, one animal raised its tail, while a second performed a naso-anal investigation or followed the first animal. In the second posture, one or both animals, after a fight, occasionally curled their tails ventrally, to form a semicircle. This is also noted in the water shrew (Eisenberg, 1964).

Mechanical Transmission of Information

Among the Soricidae there are different, often rather conspicuous sound patterns with high frequencies (Crowcroft, 1955; Herter, 1957; Wynne-Edwards, 1962). In Sorex, staccato squeaks and soft twittering or whispering sounds, in which the first group particularly belongs to defensive behavior and aggression, have been heard (Crowcroft, 1955; Wynne-Edwards, 1962). “It has apparently escaped notice that the staccato squeaks identify the male sex in Sorex araneus” (Crowcroft, 1955, p. 75). Twitter of soft notes “may act as a warning to other members of the species and thus aid mutual avoidance.” In Crocidura leucodon, the females utter rhythmic calls, by which they evidently announce their readiness for copulation to the males; during copulation, they utter a rattling sound (Herter, 1957). The males of Neomys fodiens follow females with high-pitched, rhythmical series of sounds. In Talpa there seem to be defensive sounds, which may also have a territorial function (Herter, 1957).

In Neomys fodiens the main frequencies, which are uttered in connection with reproduction, lie near 12,000 Hz; in Sorex between 10 and 12,000 Hz. Drumming with the hind legs is known in Petrodomus. These animals also utter a cricket-like chirp (Walker, 1964). The sounds of Blarina extend far into the ultrasonic range, which may be true of many sounds of Insectivora. Echolocation has also been pointed out (Walker, 1964). Of Sorex minutus sounds made with the teeth are described, possibly serving as danger signals. Special investigations into the significance of tactile reception in communication are not yet available.

Optical Transmission of Information

Generally the eyesight is far inferior to the sense of smell and the sense of hearing, yet there are some groups which possess welldeveloped eyes (especially Macroscelididae). Studies of the significance of optical signals in communication do not seem to be available. Yet it is precisely these in the Macroscelididae, some of which are noted for conspicuous color patterns (for instance, Rhynchocyon), which probably represent signal structures. It should be added that they are day-active animals and have also been heard to utter numerous sounds (Walker, 1964).

DERMOPTERA

Nothing is known about the modes of communication in this order, the only genus of which, Cynocephalus, consists of only two species. One call has been described: “The calugos utter a rasping cry, that is probably an alarm call” (Walker, 1964, p. 180).

CHIROPTERA

Bats hold second place among the mammals in regard to richness of species. They are subdivided into 17 families with about 178 genera and about 1000 species. Generally, the sequence of significance of the receptors seems to be the following: hearing, sight, smell. This is doubtlessly connected with flying ability. Yet there are certain modifications: whereas in Microchiroptera the sense of hearing dominates, in Megachiroptera the eyesight is also well developed. One of the main functions of the sense of hearing is connected with orientation in space on the basis of echolocation. These receptor systems have been examined very intensively during the last years; however, about the communication proper of Chiroptera rather little is known.

Chemical Transmission of Information

In Pteropus giganteus Brünn, the members of a group recognize one another by an individual odor. Newcomers are sniffed at at the genital and at the neck regions (Neuweiler, 1962). Within colonies strict orders of rank are formed; a mature male is at the head, the further succession generally is defined by age and strength (Neuweiler, 1962). The neck glands of mature males secrete a brown-red, penetrating, musk-smelling secretion as the stiff neck hairs fall out. The males rub wings and the nearest part of the dwelling place with this odor substance, which is found also in the urine. Details about the significance of this substance are not yet known. Females of Pteropus recognize their young by individual odor (Neuweiler, 1962). The Microchiroptera also possess odor glands. It is said of Noctilio leporinus that one may notice the odor up to a distance of 100 meters; odor glands may be found at the front, upper lip, neck, and anal region (Eisentraut, 1957). These glands certainly transmit significant information connected with reproduction and rearing of the young, but specific studies of this have not been made. In many species where there are “childbeds,” the young are able to recognize their own mother by odor (Eisentraut, 1957).

Mechanical Transmission of Information

The sense of hearing, extremely well-developed in connection with echolocation—particularly in Microchiroptera—has effectively promoted the evolution of the acoustic transmission of information. Thus, one may find in Chiroptera generally a richly developed repertoire of sounds which, however, has been examined extensively in a few species only. This development has been influenced by the tendency to socialize, characteristic of many species, as well as by the particular requirements of rearing the young and of copulation, on the basis that flight is the almost exclusive means of locomotion. In Rousettus, the reproduction partners utter specific sounds during copulation; whistling defensive sounds of the female have frequencies of 1500, 200, and 500 Hz, whereas the growling sounds of the male show more sound character (Kulzer, 1958). There is voice contact between the young and their mother which may also contribute to individual recognition; the young develop these sounds in addition to echolocation sounds, unlike Myotis, in which the voice-contact sounds shade into the echolocation sounds (Eisentraut, 1957). In Pteropus giganteus Brünn also, the cohesion between the young and their mother is guaranteed by voice-contact sounds (Eisentraut, 1957). Myotis daubentoni seems to utter certain clicking noises (in the range of audible sound) connected with territorial behavior (Eisentraut, 1957). Meeting sounds, in colonies often developed as location sounds, are very common in Megachiroptera; the colonies often become conspicuous over great distances by the rather loud noise they produce. The frequencies of these sounds are in Pteropus between 3000 and 10,000 Hz, with main frequencies between 6000 and 10,000 Hz (Nelson, 1964; Thomson and Owen, 1964). The following has been observed in Erophylla planifrons in connection with a roosting cave from which there emerged a continual squeaking: “Perhaps their bickering cries were incidental to the adjustment and proper spacing of the individuals.” Reportedly, there were several hundreds, covering the limestone walls (Allen, 1939, p. 220). In the hammerheaded fruit bat (Hypsignathus monstrosus) of the Congo region, only the males have an enormous enlargement of the larynx and a pair of immense pharyngeal sacs. They utter, sometimes for hours, strong calls, repeated twice or thrice every second (Allen, 1939). In Epomophorus, the males take up solitary stations at night “and call to each other” (Fitzsimons, 1919-1920). The calls, which sound like strokes with a metal hammer, seem to be serving district, local, and perhaps also individual marking.

This highly specialized group, including many species, may provide many interesting details concerning the transmission of information by acoustic as well as by tactile signals.

Optical Transmission of Information

Though the eyesight is rather well developed in several species, particularly the Megachiroptera, investigations of optically effective signal systems serving communication have not been made. It is known that occasionally conspicuous colors are shown, for instance the orange-spotted pattern of Myotis welwitschii venustus, which may be a structure used for signaling. Analogous facts apply to the Diclidurus species, which also has conspicuously large eyes.

EDENTATA (XENARTHRA)

This group includes three recent families with 14 genera and nearly 30 species. In the Myrmecophagidae, the sense of smell dominates the generally poorly developed eyesight and sense of hearing, while in Bradypodidae the eyesight is relatively well developed and color recognition has been demonstrated. In Dasypodidae, finally, all three senses seem to be passably well developed, although investigations of communication have not been undertaken; only occasional observations have been made (Krieg and Rahm, 1960). The different members show high, and often very partial, specializations. Myrmecophaga seems to live mostly solitarily and is predominantly day-active, whereas Tamandua is prevalently dark-active (Krieg and Rahm, 1960). Genuine territorial behavior probably has developed in Bradypodidae and Dasypodidae which, likewise, are dark-active.

Chemical Transmission of Information

In Myrmecophaga, during intraspecific meetings, the urine and the anogenital region are intensively sniffed at; on these occasions significant information (probably also individual) is probably transmitted. The males of Bradypus tridactylus boliviensis Gray have in the middle of their backs, closely behind the shoulder region, a skin gland; its secretion is rubbed against a substrate for marking. The pelvis gland of Euphractes has an analogous function.

Mechanical Transmission of Information

In Myrmecophaga, six types of sounds are known; they probably have defensive function and serve as voice contact. They have not been examined. Bradypus utters conspicuous calls, probably location sounds (Krieg and Rahm, 1960), which may also transmit information during the rearing of the young (Beebe, 1940). In Dasypodidae, genuine sounds are not known.

Optical Transmission of Information

Optical signal systems of communication in Edentata do not seem to have been investigated.

PHOLIDOTA

To this order belongs only one family with one genus and about seven species. They are mainly nocturnal and seem to live solitarily. Among their senses, eyesight is very inferior. Nothing is known about their territorial behavior except that the animals seem to be rather place-fixed. Even about reproduction behavior, little is known. Chemical, and above all, tactile stimuli seem to be significant for the cohesion of mother and young; the young cling to the tail or back of their mothers during transportation, which is particularly significant in arboreal species. Rattling and hissing are the only utterances which have been described, and they are probably defensive sounds (Krieg and Rahm, 1960).

LAGOMORPHA

To this order, the systematic arrangement of which is still not clear, belong two families which includes about sixty-four species. The Ochotonidae are nocturnal, the Leporidae partly active during certain times of dusk or daylight. Some species live socially.

Chemical Transmission of Information

Oryctolagus possesses a chin gland (“submandibular organ”), particularly developed in males during rut, which serves in marking behavior (Mykytowycz, 1958, 1959, 1960, 1962). In Lepus, it is not as well developed. Castration leads to a decrease in the size of the gland and a reduction in readiness for marking behavior, yet one can restore the gland by doses of testosterone (McHugh, 1958). The males of Oryctolagus show, during rut, the tendency “of enurination, in which the buck projected a jet of urine at the doe” (Southern, 1948, pp. 172, 193). The territories of the males of Sylvilagus aquaticus are estimated at nearly two acres, those of the females at four acres (Toll et al., 1960). For Oryctolagus cuniculus ranking in colonies has been demonstrated (Mykytowycz, 1958-1960). In Lepus californicus the sense of smell seems to be used to detect other jack rabbits (Lechleitner, 1958). During reproduction it has been observed that males covered an area of about thirty to thirty-five acres. On this occasion, the scent from the anal glands seems to serve for marking (Lechleitner, 1958). For Lepus americanus total territories were found of about seven acres for the females and eighteen acres for the males, with a daily range of action of about four acres (in both sexes). In Ochotona princeps, territorial behavior has been pointed out and scent marking has been thought probable, when, for example, cheeks are rubbed against a rock (Kilham, 1958). In Ochotona hyperborea yesoensis Kishida, the territory is estimated at about thirty meters in diameter (Haga, 1960).

Mechanical Transmission of Information

The calls of “piping hares” are well known. There seem to be at least two types of sounds; one seems to be an alarm call and the other to indicate territory (Haga, 1960; Kilham, 1958); these sounds have not been studied. In the Leporidae, there seem to be only defensive sounds: emergency calls and alarm drumming with the hind legs. Alarm drumming is explained as ritualized flight behavior [intention to jump off (Eibl-Eibesfeldt, 1957, 1958)].

Optical Transmission of Information

Generally, the eyesight of Lagomorpha is rather well developed, and, at least in the Leporidae, there are optically effective signal systems. During rut, the male of Oryctolagus cuniculus runs away from the female in a stiff posture, meanwhile showing the white bottom side of the tail (the buck parades before the doe with the tail elevated over the back), an apparently visually effective signal action (Southern, 1948). Optical transmission of information perhaps also takes place through the peculiar gambols of the Leporidae, for instance, Lepus californicus, Lepus townsendii (Anthony, 1928; Wynne-Edwards, 1962). In Lepus alleni, L. callotis, and related forms, conspicuous flank patterns exist which, by means of special skin-muscles, can be dragged dorsally; these white marks are turned toward strangers as the animal zigzags from side to side. This behavior may be observed particularly during rutting time (Nelson, 1909; Seton, 1909; Wynne-Edwards, 1962).

RODENTIA

This most voluminous group of mammals includes 37 families, about 352 genera, and far above 3000 species. Their behavior has been presented in summary (Eibl-Eibesfeldt, 1958). Some Rodentia occupy territories; some have collective territories; some live in tribes or larger social groupings. Connected with this, different methods of intraspecific information transmission have developed, but they have been clearly examined in some species only.

Chemical Transmission of Information

Very frequently side glands are encountered in Rodentia, specially in Cricetinae and Microtinae (Schaffer, 1940). Females of Mesocricentus auratus mark with a secretion of the genital region, Marmota with a secretion of the anal glands (Armitage, 1962, 1965; Dieterlen, 1959). Marking with urine has been pointed out in Sciurus, Rattus, and Mus. (Barnett, 1958; Dücker, 1957; Ebil-Eibesfeldt, 1951). Mus also uses glands on the soles for marking, the arrangement of which can transmit information concerning the direction of the running. Arvicola terrestris scherman Shaw wipes the secretion off the flank glands by means of the hind legs and smears it on the ground—a removal of secretion which has been derived from displacement-grooming (Eibl-Eibesfeldt, 1958). In Heteromyidae the ventral rubbing serves exclusively the function of chemical communciation. In Perognathinae and Dipodomyidae scent marking has developed features of sand-bathing (Eisenberg, 1963a, b). In Nyctomys sumichrasti, the males give off a secretion which probably stimulates females (Birkenholz and Wirtz, 1965). Glis, as well as Mus, Cricetus, Ondatra, and Microtus, possesses preputial, respectively clitoris, glands (Schaffer, 1940). During scent marking, Glis presses the anal region firmly against the substratum and often draws rather long traces of secretion (Koenig, 1960). Analogous routines are known in Dasyprocta. The marking behavior of Aplodontia (with feces and urine) has been described (Pilleri, 1960a). In Cuniculus paca L., urine marking and establishing specific places for the deposit of feces has been observed (Pilleri, 1960b). In many Rodentia which show high intraspecific aggressiveness, chemical communication is of decisive importance for the recognition of specific individuals (Rauschert, 1963), as, for instance, in Lemmus (Arvola et al., 1962; Frank, 1962). Typical on this occasion is an oral initiation of contact, the so-called “identification kiss” (Frank, 1962; Reichstein, 1960, 1962). The squirting of urine, directed against another member of the species, has been observed in Cavia, Dolichotis, and Erethizon (Eibl-Eibesfeldt, 1958; Kirchshofer, 1960). This may indicate a chemical information transmission.

Very conspicuous anal glands have developed in Castoridae and Ondatra, more so in males than in females. The secretion is deposited on stones or mud and strongly attracts conspecifics. Another beaver covers already marked places with soil, then adds its own scent mark; this may be repeated often, so that little hillocks develop, sometimes to a height of four or five feet (Wynne-Edwards, 1962).

Mechanical Transmission of Information

Generally the Rodentia have a well-developed sense of hearing, in which the upper limit may extend far into the ultrasonic range; in Rattus, Micromys, Mus, Cricetus, Mesocricetus, Cavia, Clethrionomys, Glis, and Muscardines it has been possible to show reactions in frequencies between 6 and 100 kHz; Peromyscus maniculatus hears up to 80 kHz, P. nasutus (which has larger external ears) up to 100 kHz (Anderson, 1954; Hudson, 1922; Kahmann and Ostermann, 1951; Reschke, I960; Tembrock, 1959; Zippelius and Schleidt, 1956).

Vocalization in this group is widespread and serves to transmit various information; thus within one species, there are often several sound patterns (Fig. 2). As sounds in many Rodentia are flight-releasing, certain vocalizations serve to “neutralize” noises produced by motion, especially during the approach for reproduction. The tendency to repeat sounds, in which rhythmicity may deliver additional information, may be understood as a device to improve orientation and to add redundancy. In a number of cases it can be shown that such courting sounds have been derived from the infantile repertoire of sounds, where they primarily release actions of care (Eibl-Eibesfeldt, 1958).

Rhythmic sounds during rut are uttered, for instance, by the males of Cricetus cricetus (Eibl-Eibesfeldt, 1953), Clethrionomys (Flemming, 1965; Schleidt, 1950), Microtus agrestis (Eibl-Eibesfeldt, 1958), Sciurus vulgaris (Eibl-Eibesfeldt, 1951), Micromys minutus (Frank, 1957), Chinomys nivalis (Frank, 1954), Hydrochoerus. In Clethrionomys the frequencies of the sound are located near 15,500 Hz, its duration runs to 0.1 to 0.5 sec. The males of Lemmus lemmus utter rhythmic sound sequences during rut, while moving about in a strange tripping walk, which shows typical, individual features; with increasing intensity they change their timbre (Arvola et al., 1962; Frank, 1962). The function of the trills of Citellus armatus has not been welldefined; they last 1 to 2 sec, during which about 15 to 25 sounds per second are uttered, with a frequency between 6000 and 8000 Hz. In addition to these, chirp calls are uttered: series of two or four sharp sounds at 0.2-sec intervals, at a frequency of 4000 and 5000 Hz. “The series is repeated every 5-15 seconds for as long as 30 minutes.” During rut the vocalization differs, the call occurs at very regular intervals and may continue for more than an hour. Males do most of the calling in an upright, slouched posture (Balph and Stokes, 1963). Similar facts have been described of Tamias striatus (Forbes, 1966). In Glis glis, both sexes utter squeaking sound sequences that are clearly audible for about 50 meters; these squeaks of 2-to 3-sec duration follow immediately one after the other, at an average of 50 to 100 times, sometimes up to 300 times or more often, so that one strophe lasts 10 min or more. Analogous facts are known of Eliomys quercinus and Glaucomys volans and probably indicate an adaptation to a specific environment (Koenig, 1960). The strophe of Glis glis shows variability and internal segmentation. The males of Nyctomys sumichrasti utter a “groomp” produced at about 5-sec intervals for a duration of about a minute. The chest swells slightly as if the sound were produced by an intake of air (Birkenholz and Wirtz, 1965). Erethizon dorsatus utters sound sequences, the main frequencies of which lie between 250 and 550 Hz.

Warning calls are widely spread in Rodentia as in Marmota, Citellus, cynomys, Microtus brandti (Armitage, 1962, 1965; Balph and Stokes, 1963; Müller-Using and Müller-Using, 1955; Reichstein, 1962).

In social species, there are also contact vocalizations, particularly conspicuous in Lagostomus trichodactylus, which live in common burrows of about fifteen to thirty animals dominated by one male (Hudson, 1922). Young animals in the Rodentia have at their disposal specific sound patterns which release care behavior and maybe even specific actions.

Moreover, defensive sounds are very common. They are distinguished by a harsh onset at extremely high amplitude and are generally very brief. In Clethrionomys species, especially CI. rutilus, it has been shown in a number of cases that fighting behavior could be inhibited by playing back the defensive sounds. The maximum frequencies (average values) are distributed among Clethrionomys in the following manner: CI. glareolus, 2.0 to 2.5 kHz; Cl. rutilus, 1.4 to 1.8 kHz; Cl. rufocanus, 2.8 to 3.6 kHz; Cl frater, 2.0 to 2.5 kHz (Flemming, 1965).

Acoustic receptors probably have special significance in Massoutiera; echolocation may be present also, but details are unknown. Mechanically produced alarm signals or ritualized aggressive movements are the rattling of the tail in Hystrix, the drumming with the paws in Meriones, Tatera, Gerbillus, and Jaculus (Eibl-Eibesfeldt, 1958; Kirschshofer, 1958). The grinding of teeth, widespread in Rodentia, has originated from the ritualization of food gathering (gnawing). Experiments employing dummies in Clethrionomys showed that, in fighting behavior, this production of sounds is functional and may release grinding of teeth in other individuals as well (Flemming, 1965). Castor signals by thumping his tail on the water.

Tactile stimuli are of great significance in the intraspecific fighting behavior of Rodentia. In agonistic behavior, many species rise on their hind legs and drum at each other with the forepaws. Physical contact is frequent. In the case of species living mainly in the water, vibrations of the water may also serve to transmit information; this has not yet been investigated in detail. The actions of social grooming have great significance.

Optical Transmission of Information

Intraspecific meetings in many Rodentia are marked by specific postures (Fig. 3) (Balph and Stokes, 1963; Clarke, 1956; Getz, 1962; Johst, 1964; Nero, 1959) such as elongated posture during approach; down alertness postures: down slouched, down extended, and down coiled; coiled, boxing, raising of paws, pushing of paws; tail-flicking, sigmoid tail erection, fanned-tail posture; supine posture; displacement-digging; displacement-toilet and grooming. Special ear postures, piloerection, and different degrees of shutting the eyes may also have signal significance. Ritualization also leads to development of an intimidation display which perhaps represents a combination of aggressive and defensive tendencies (Fig. 4) (Tembrock, 1964). In some conspicuously colored Rodentia there are probably also optically effective signal structures (Cricetus, Eibl-Eibesfeldt, 1953, and elsewhere). In Jaculus there are conspicuous black and white or pure white tail tassels which may supply flight signals (Eibl-Eibesfeldt, 1958). The white patches in the tail region of the Dolichotis species have an optical signal effect, which in fleeing animals ensures visual contact by the pujrsuer. Cuniculus has developed conspicuous color patterns and very large eyes; here, too, optical communication may be presumed.

CARNIVORA

The recent Carnivora are subdivided into 7 families and about 100 genera with about 290 species. The sense organs, highly developed owing to the nature of food gathering in Carnivora, have greatly advanced the elaboration of information transmission. The large variety of structures and living habits has led to great diversity in the development of types of communication in the various groups. Here a great number of problems have still to be investigated.

Chemical Transmission of Information

Probably without exception, the sense of smell is rather well developed in all Carnivora, hence also various forms of chemical signaling. Skin glands are richly developed in Carnivora. Of special significance are glands in the anal and caudal region (circumanal glands, anal pouches, pregenital glands, viol glands (Vulpes) (Friedrich, 1959; Schaffer, 1940; Spannhof, 1966). Apart from the secretion of the glands, feces and urine are used for marking and, when equipped with specific secretions, are able to transmit information. The position of the gland often demands certain modes of behavior during secretion, and again the secretions are deposited in specific places. In addition to the indirect chemical transmission of information via scent marks, direct chemical signaling by sniffing the partner, generally connected with certain modes of behavior, is significant for many Carnivora. In general two main spheres can be distinguished: (1) the anogenital region and (2) the head-neck region. On the head there are quite often special glands, in Vulpes, for instance, the circumoral glands (Friedrich, 1959). The “odor control” in Canidae often is done by means of scent reception at neck, nose, sides of the head, and the corners of the mouth. In this way also information can be received from a recognized conspecific about the food which has just been eaten. In Carnivora, this seems to be a very characteristic form of information transmission. The circumoral glands are sexually dimorph and are better developed in the male of Vulpes. Viol and circumoral glands show cyclic changes, connected with rut, and toward the end of this time there are symptoms of degeneration. Both glands contain greaselike substances in abundance. Anatomically, they are related to sebaceous glands (Friedrich, 1959). It may be supposed that the secretion of the viol gland is skimmed off at the entrance to the den. The testicles of Canidae (especially Vulpes) are said to secrete sex-specific secretions (Schaffer, 1940).

The actual center of smell is the anogenital region. The control of the anal region, especially in socially living species, displays a particular expressive behavior as, for instance, in Canis lupus (Fig. 5) (Schenkel, 1948). Here the presentation of the anal region is a specific behavior. Individuals of low rank withdraw from anal control by curving and bending their tails. Consequently, certain modes of behavior are connected in a complex manner with principles of chemical signaling. In females, presentation of the anal region often occurs during rut so that at this time the tail is constantly raised. In the domestic dog this presentation, because of domestication, seems to have become almost permanent in both sexes. Additionally, the squirting of the urine is connected with this behavior, which in many cases includes optically effective components. Females can transmit information about their physiological status by way of these urine marks (Stanley, 1963; Tembrock, 1957a, b). Bears often roll in urine and then rub against vertical substrata in their surroundings (“rubbing trees”); an action which generally is explained as territory marking (Meyer-Holzapfel, 1957). In both sexes, foxes mark their reproduction partner with urine.

In Canidae there are about four modes of urine-marking behavior: (1) squatting position, (2) crouching position, (3) drawing in of one leg (one hind leg is lifted in a horizontal angle), (4) lifting of a leg (the behavior described in (3), but with vertical swinging) (Gauthier-Pilters, 1962; Kühme, 1965; Seitz, 1959; Tembrock, 1957a, b). In Nyctereutes, smelling the urine scent of a rival releases readiness for aggression in the owner of a territory (Heimburger, 1959; Seitz, 1955). The marking places in this species have to be renewed every twentyfour hours to remain effective (Heimburger, 1959). Canidae react to certain substances and scent marks by rubbing the temples, neck, and shoulder sides or by completely rolling on these substances (Heimburger, 1959). In Canis species, the squirting of urine often is followed by scratching with the hind legs.

In Felidae urine-squirting is also widespread, primarily in the male. Feces are often used for marking and are deposited in specific places. In Crocuta crocuta “the animals’ habit is to defecate in regular latrine areas” (Wynne-Edwards, 1962). Because of the high content of bones in the food, the feces appear to be white, which probably has an optical effect (Holzapfel, 1939; Matthews, 1939).

In Vulpes macrotis “scats were found along the trails; at dens, and occasionally near objects such as bits of bone or other animal remains” (Egoscue, 1962, p. 488). In Vulpes vulpes the anal pouches are subject to an annual cycle. This fact makes a relation to behavior conceivable; at times, then, the connection may be feces marking, at other times, sniffing (Spannhof, 1966).

The marking of territory certainly has very different functions. As signposts, chemical marks can serve orientation. In Martes martes (Fig. 6), scent marking starts after the family bonds have been severed (Goethe, 1964; Herter and Ohm-Kettner, 1954); the same can be said of Vulpes (Stanley, 1963; Tembrock, 1957a, b; Vincent, 1958). At certain times, Vulpes marks all exposed and also all new objects in the territory [in captivity, Tembrock (1957a)]; analogous facts are true of Mustela nivalis (Goethe, 1964). In Martes, the secretion of the pregenital glands is used to mark the territory. After marking by slithering, urination occurs. In Meies and Martes, and doubtless in various other species, scent marking has social functions also (Eibl-Eibesfeldt, 1950; Goethe, 1964). During rut, Mustela putorius secretes great quantities of rectal gland secretion (Goethe, 1964). Apart from the “threatening scent,” Spilogale putorius secretes a characteristic nest scent. This signal serves as a chemical stimulus inducing nursing behavior. Females are said to have this scent in estrus. In Viverridae, the anal pouch or special perineal organs deliver secretions which transmit chemical information. Here again, specific modes of behavior have been developed for the placement of these secretions (Dücker, 1965; Schaff er, 1940). Certain scent marks are renewed regularly; before and after the marking, the places are examined olfactorily (Dücker, 1965). Males of Viverricula squirt urine during the reproductive season (Dücker, 1957, 1965). Helogale undulata rufula marks with the cheek glands by rubbing them against the corresponding substratum. Marking by means of the anal pouches, either by handstanding or slithering, then follows (Zannier, 1965). Rubbing with the back of the head against such spots also may cause self-marking. The details of the kind of information which is here transmitted are still unknown. In Suricata, the male has anal glands which produce a secretion used to mark various objects. He also rubs his body along the mark so as to smear the secretion on his own fur (Ewer, 1963). Two functions of marking behavior have been demonstrated here: first, the secretion serves to characterize and thus to indicate occupancy of a specific area. Second, it might serve as a warning signal to others visiting the spot later. In Bassaricyon, feces marking has been suggested (Poglayen-Neuwall and Poglayen-Neuwall, 1965). Genuine marking by slithering over the substratum is found in both sexes; similar facts apply to Potos (Poglayen-Neuwall, 1962). Ailurus also marks in this way.

Mechanical Transmission of Information

Acoustic communication in Carnivora is rather widespread; one of the reasons for this might be found in the fact that the bigger species particularly have but few natural enemies. On the other hand, the greatest part of the species lives solitarily, except during the time of reproduction. In many cases the manner of living makes difficult the possibility of chemical and visual transmission of information, so that acoustic signaling is often essential. One of the functions here is the inhibition of aggression, which, because of the dangerous tools employed by beasts of prey in fighting, tends to ensure the preservation of the species. On the whole, the conditions for vocalizations serving communication prove to be rather complex and therefore have led to different trends of evolution within the individual families (Pinnipedia holding a special position). The Canidae, which show strong tendencies to social life, have at their disposal a rich repertoire of sounds (Fig. 7). Four groups of sounds having specific information value can be distinguished. (1) Warning sounds (transmit excitation, a general state of arousal, increase in the tendency to receive information further), (2) A-eliciting sounds (decreasing distance), (3) Weliciting sounds (increasing distance, sounds of defense),* and (4) infantile sounds (releasing care behavior; in adult animals these sounds appear in a ritualized manner).

The A-eliciting and W-eliciting sounds may transmit individual, sex, and physiological status as additional information. Besides, the blending of motivations may result in mixed sounds (Tembrock, 1960, 1963). Warning sounds may also announce territory. Here the typical sound in Canidae is barking, a single sound which may be repeated irregularly; yet in connection with this function it does not form genuine strophes. Repetition of the barking, its frequency and its duration, may determine the contents of information; amplitude and frequency range may also be determining features (Tembrock, 1965).

The A-eliciting sounds are rhythmic and generally also strophic; in the Canis group they have fused into a continuous string of sounds— howling; however, rhythmic barking sounds generally introduce howling. The barking strophe in “vulpine” Canidae transmits acoustic information over longer distances corresponding to the howling strophe in “canine” Canidae. In close contact, similar rhythmic sound sequences are used, but with different tone quality (Tembrock, 1959). Probably information about sex and the individual is also transmitted through these A-eliciting sounds. Differences in the frequency range are probably the main means of individual characterization; the structure of the strophe, remaining fairly constant throughout the individual’s life, may be a contributing factor.

The infantile sounds are also distance-decreasing. They release caring behavior in the adult individuals; in some cases they reappear in a ritualized form in the acoustic interchange between reproduction partners (Fig. 8). They are marked by high frequencies, in Vulpes between 1800 and 4000 Hz. The W-eliciting sounds generally are concomitant with specific behavior patterns, and their effect is to increase the distance between sender and receiver. Primarily, they are emitted in the rhythm of the accelerated respiration rate, then checked, and, in the extreme, voiced as explosive sounds with onset at the highest amplitude.

Rhythmic sound patterns are also uttered by Ursidae in social communication—for instance, by the mother in luring its young. Long sounds and single sounds have a more W-eliciting character; yet these have not been examined in detail. A peculiar case is presented by the “humming” sounds that young bears utter during suckling; here also, rhythmic elements are noticeable. Rhythmic lip sounds are uttered as contact sounds.

Rather differentiated sound patterns also occur in those animals. Bassaricyon has contact calls—rhythmic sound sequences, the information content of which is obviously determined by pitch and intensity (Poglayen-Neuwall and Poglayen-Neuwall, 1965). The typical contact call has a squeezed quality and is produced at a low level of intensity, about forty to fifty times a minute. Similar facts may be observed in Nasua. In Bassaricyon there are defensive and threatening sounds and, furthermore, fright calls, fear calls, alarm calls, and intimidation calls; however, many questions of motivation and also of function in communication have not yet been answered (Poglayen-Neuwall and Poglayen-Neuwall, 1965). Mixed sounds (superposition or blending of motivations) have also been observed. In Mustelidae one may distinguish the following acoustic signals: sounds of nestlings (releasing care actions), begging sounds of the young, and, in ritualized form, rut calls of the adults (rhythmic sound sequences), defense sounds, warning calls (threatening cry), sometimes harshly expelled sounds, pain calls (when wounded), hissing sounds, threatening snarls, and sounds of social interchange (typical rhythmic sequences, often also strophic) (Goethe, 1964). As A-eliciting sound patterns, this last group of sounds can probably be derived from the sounds of the young.

Spilogale has a high-pitched screech and in other situations utters a series of throaty grunts. In Viverridae, Arctitis binturong utters a long sound as a contact call which is repeated at short intervals (Dücker, 1965; Ogilvie, 1958). Rhythmic sound sequences during mating contact also have been described in Arctogalidia trivirgata males, Viverricula malaccensis, and Genetta tigrina (Dücker, 1965). During copulation, Cryptoprocta fer ox utters mewing sounds (Vosseler, 1930). Typically rhythmic sound sequences during mating behavior have also been observed in Herpestes ichneumon (Dücker, 1965). The communication between the young and the caring adults is directed mainly by acoustic signals, which in Genetta and Suricata occur very frequently. Later in the development, there appear voice contact sounds which, especially in gregarious species, are also uttered by adult animals (Genetta, Suricata, Helogale, Mongos). In Mungos mungo (= Cr ossär chus fasciatus) frequencies of about 640 to 904 Hz have been determined. Probably, by means of different frequencies, sexually specific and individually specific information is transmitted (Dücker, 1965; Thomson and Owen, 1964). During food gathering, Helogale and Mungos utter conspicuous trills which have specific communicative function in these gregarious species (Dücker, 1965; Zannier, 1965). In Suricata, warning signals which indicate specifically whether the enemy is in the air or on the ground can release different patterns of behavior (Ewer, 1963). In this species, barking alarm sounds have been described (Ewer, 1963). These may “spread” over the whole colony. Sounds of defense are also frequent; growling is known in Arctitis, Nandinia, Viverricula, Genetta, Herpestes, Mungos, and Suricata (Coues, 1875; Dücker, 1965). Explosive sounds have been described in Genetta, Mungos, and Helogale; chattering in Herpestes, Mungos, and Suricata.

In Felidae (Denis, 1964) vocalization represents a significant means of communication. The following types of sounds may be distinguished (Reschke, 1960): monosyllabic short sounds—hissing (guttural), panting, “knocking,” expiratory bursts, “bird call” (only Felis concolor), inspiratory gasps (only Panther a par dus, inspiration sound); monosyllabic short to long sounds—hissing (palatal “hissing”), caterwauling; bisyllabic short to long sounds—roaring, roaring call (only Panthera tigris), mewing, squealing (only Felis concolor); sounds with a changing sequence of impulses: cooing, snorting, rumbling, growling, grunting, gargling, snarling, purring (Fig. 9). Many of these types of sounds can be arranged in sequences serving to transmit specific information; for this purpose, they can also be patterned in specific rhythms and strophes involving as an option the combination of different types of sounds. Such sound sequences appear particularly in Panthera leo, P. pardus, and P. onca. Yet in Lynx and Chaus too, males during rut utter call sequences which, especially in Chaus, show changes in the type of sound within the strophe.

A considerable part of the sound repertoire of Felidae is represented by W-eliciting vocalizations (Fig. 10). This may be traced back to the fact that, in this way, the intraspecific use of dangerous fighting weapons can be prevented. In ritualized form, these sounds appear during and after copulation, as here too agonistic behavior is activated by transgressing the minimum distance and may often be actualized after sexual behavior. The male Pantherini therefore utter in these situations specific, distance-increasing defensive sounds. Certain specific rhythmic sound sequences in this group serve as communication and may probably also transmit information about the individual. Snorting represents a special type of sound; it has developed characteristically in Neofelis nebulosa, Panthera tigris, and P. uncia but is probably even more widespread (Reschke, 1960). The large call sequences of Panthera leo, P. pardus, and P. onca perhaps serve to mark territory and possibly characterize the individual also. Details of this are not yet known. The conspicuously long call sequence of Crocuta crocuta may have a similar function; the so-called laugh certainly is a socially positive A-eliciting acoustic transmitter of information.

Optical Transmission of Information

Carnivora have at their disposal a rich repertoire of displays (only some of which have been studied) which transmit visually effective information, ritualization being the basis of development. Rather well known are many signal systems in Canidae and Felidae (Leyhausen, 1950, 1956; Tembrock, 1957a). The bases of these optically effective systems are (1) somatic motor patterns (movements of the trunk and the extremities and movements and postures of the tail), (2) visceral motor patterns (facial expression, head-neck region), (3) autonomic motor patterns (vasomotoric, pilomotoric, iris movements).

The signal structures, too, are closely related to these three function systems; specific patterns of design and specific distribution of colors in the fur, as well as pigments of the iris, may provide essential assistance for the effectiveness of these systems. Phylogenetically, we have here three autonomous, variously interacting systems, each having undergone a different evolution, so that, for example, fur, for other reasons well-developed, may decisively inhibit the evolution of facial expression. Apart from the fur, the main cause for this inhibition in Ursidae is probably relatively poor eyesight (Meyer-Holzapfel, 1957), so that other visually effective signal actions, aside from very conspicuous ones (for instance, getting up) have developed hardly at all.

Somatic Motor Patterns. The optically effective signal actions developed in this field may be derived from food gathering, comfort behavior, protection and defense, and more rarely from behavior connected with rest and sleep, urinating and defecating, as well as reproduction. From food gathering may be derived ritualized movements of the locomotion apparatus, especially of the front extremities (beating in Felidae), but also crawling and other forms of movements. Ritualized movements of sharpening the claws, perhaps of marking (as expressive movements:, Ursidae), of rubbing oneself, of rolling, of certain positions of trunk and tail (and from the stretching syndrome) may be derived from comfort behavior. From protection and defense may be derived ritualized flight behavior, crouching, and defense movements and postures. Certain postures and perhaps also scratching have originated in rest and sleep behavior. Certain positions of the legs (Canidae) and of the tail may be derived from urination and defecation behavior, respectively. A ritualized mounting may have originated in reproduction behavior.

Visceral Motor Patterns. The entire expressive behavior of this group may be derived from food gathering, except for the outer ears, which serve primarily for sound localization. Yet, in the mammals, even they probably developed originally in the service of food gathering, a process occurring in the Mesozoic owing to pressure from the dominant reptiles, whose orientation was mainly optical. However, one must consider that, particularly in food gathering, certain protective movements of the head-neck region became necessary; when ritualized, they have become elements of expressive gesture (Andrew, 1963). Particularly, the large sense organs had to be protected. The most important muscle differentiations are M. auriculo-labialis, M. frontalis, M. maxillo-nasolabialis, M. nasolabialis, M. orbicularis oculi, M. orbicularis oris, M. palpebralis, M. platysma, and M. zygomaticus. Certain movements of the head in connection with food have become ritualized. Lateral shaking as, for example, in spitting out inedible food, has been ritualized in a defense gesture. Vertical movements of the head (swallowing food, hence + function), when ritualized, often have an A-eliciting function. Similar facts are true for ear positions: in protection (-adjustment to the stimulus), leveling the ears when turning to the stimulus (+ adjustment), pricking up the ears. Correspondingly, this can also be transferred to communication in ritualized form. Wide lip slit (M. zygomaticus, M. nasolabialis, M. platysma) aids the teeth during food intake (ritualized —, W-eliciting: baring the teeth); narrow lip slit (M. orbicularis oris) shuts the muzzle and covers the teeth (ritualized +, A-eliciting). The same is true of the eyes.

To this range of display in Carnivora belong different positions of the ears; wrinkling or smoothing the forehead; the whole range between open and narrowed eyes, narrow and wide lips, closed and wideopen mouth; baring the teeth; positions or movements of the head.

Autonomic Motor Patterns. In the head area this includes the width of the pupils and focusing (or not focusing) as well as the position of the eyes. To what extent vasomotoric processes (and with these changes of blood pressure in certain parts of the body) have genuine signal functions in Carnivora (except Pinnipedia) is still not clear. In many species, however, the pilomotoric system, for instance, hair bristling, is optically effective.

TUBU LIDE N TATA

This order includes only one species (Orycteropus afer), the behavior of which is but insufficiently known.

Chemical Transmission of Information

From the nocturnal mode of life in Orycteropus one may guess that the well-developed sense of smell is used as a means of communication. Inhabitation of dens (for the most part self-dug) points to more specific territorial behavior patterns, but investigations into this have not been carried out (Rahm, 1960). Intensive sniffing in the anal region of the conspecific is classified as contact behavior.

Mechanical Transmission of Information

According to concurrent reports, the sense of hearing in Orycteropus is doubtlessly well developed. The outer ears are conspicuously large. Hearing may play an essential role in the search for food (the principal food source is termites). Little is known of their vocalizations. There is some information on squeaking sounds, but the function is unknown (Rahm, 1960).

Optical Transmission of Information

It is unlikely, considering the nocturnal mode of life, that optically effective signals are used in communication.

PROBOSCIDEA

This order of mammals, consisting of only two species (and genera) has been studied particularly in regard to ethology during the last few years (Kühme, 1961,1963).

Chemical Transmission of Information

The most conspicuous dermal gland of the elephants is the temple gland (temporal gland): on the surface there are hair glands, beneath these lies a large layer of apocrine glands; together they often form a lobed body of glands and through narrow passages empty into the cisterns of the sebaceous glands. The temple gland is actually a rut gland which secretes only at certain times. The scent from this gland is received by conspecifics through the trunk; during fighting behavior, too, the elephant touches his own temporal glands before his rival touches them (Kühme, 1961). Other areas of the partners body toward which the tip of the trunk is directed are the mouth, the openings of the ears, the armpits, and, above all, the anogenital region. All these cases probably entail the reception of chemical information; certainly, individual information is transmitted also (Priemel, 1930). The scent of the female’s urine seems to serve the chemical transmission of information (physiological status), since, particularly during reproduction behavior, females urinate frequently and the bull takes up the scent (Kühme, 1961,1963).

Mechanical Transmission of Information

The vocalizations of elephants have so far not been systematically examined. Generally, sound patterns with high frequencies seem to have A-eliciting functions and seem to transmit specific information intraspecifically which serves the coherence of the group (main frequencies between 640 and 1500 Hz); whereas roaring and rumbling have more defensive functions (distance-increasing, W-eliciting), with main frequencies between 80 and 400 Hz. Besides, there seems to be a further principle of information in the length of sounds (particularly in the trumpeting). The long trumpeting sounds are probably alarm calls. Yet many questions still remain open. Altogether about twenty different sounds have been described in elephants. As a warning sound, a pop-like sound made with the lips is mentioned (Kasbohm, 1964). Grunting sounds are said to be made during the initial stages of copulation (Loxodonta) (Bourlière, 1954). There are numerous references to trumpeting in various situations, but there are few certain interpretations of this behavior (Blond, 1960). A special cry has been described as an alarm signal (Lavauden, 1934). Mechanical sounds can be produced by stomping with the feet, clapping the ears (Loxodonta), beating with the trunk, rubbing against trees, breaking of trees and branches, drumming with the tail against trees, plopping of feces in flight. In addition there are respiration and digestion sounds (Blond, 1960). In this case, also, there have been no specialized investigations into their function.

Optical Transmission of Information

Elephants have at their disposal a rich repertoire of behaviors, which is determined chiefly by the position of the head and by movements of trunk and ears. An analysis of these signal actions has been made in Loxodonta (Kühme, 1961, 1963; compare Fig. 19). It may be supposed that the tusks also represent signal structures. Additional displays are shaking and nodding of the head, rolling, digging, and perhaps also sand bathing and spinning. The conspicuously colored secretion of the cheek glands may be optically effective also.

HYRACOIDEA

This order includes three genera; the number of species is said to be six to nine (Hahn, 1959; Morris, 1965; Rahm, 1964; Walker, 1964). These animals live both on the ground and in trees; the senses of sight and hearing seem to be better developed than the sense of smell. Decidedly territorial behavior has been observed, and in general there is also a tendency to form colonies (except Dendrohyrax). The species seem to be preponderantly dark-active (Rahm, 1964; Walker, 1964).

Chemical Transmission of Information

The most conspicuous dermal gland of this group is the dorsal gland, known for more than a hundred years, which in Heterohyrax represents a skin area 22 mm long and 9 mm wide (Schaffer, 1940). There is a secretion of two kinds, partly of greasy, partly of albumin-like nature. Special muscle bundles serve to empty the glands. In Dendrohyrax the dorsal spot, often differently colored, may be 7 cm long. So far, there are but few references to marking behavior (Rahm, 1964), so that the specific function of the gland is still unknown. Feces are deposited in specific places by Procavia and Heterohyrax (Coe, 1962; Rahm, 1964).

Mechanical Transmission of Information

Sound utterances have high significance in Hyracoidea communication, probably because of their nocturnal mode of life and the poorly developed sense of smell. The calls of Dendrohyrax, “a series of croaks which gradually mount the scale and end in a loud scream” (Walker, 1964, p. 1327) are particularly well known. The sound sequence seems to be rather variable. In Dendrohyrax dorsalis emini, the number of cries varies per sound sequence, which has a maximum duration of five minutes. Within the sequence an increase of intensity is typical. Differences have been pointed out between the sound sequences of several subspecies (Hahn, 1959). For Procavia different forms of sounds have been described (Coe, 1962): warning whistles and call sequences which evidently have A-eliciting meaning (contact sounds); these are heterotypical call sequences. Bumping by stamping of the forepaws has been described in Dendrohyrax (Hahn, 1959). When imitated, this has an attracting effect. The manifold vocalization of Hyracoidea still needs intensive study.

Optical Transmission of Information

Here, chiefly, the conspicuous dorsal spot, including the dorsal gland, should be noted. When threatened, Dendrohyrax dorsalis turns its back toward the enemy and displays the bare dorsal gland (Hahn, 1959). Nothing is known about other signal structures and signal actions having specific optical effects. Because of the nocturnal mode of life, hardly anything else is to be expected.

PERISSODACTYLA

This order contains six genera and about seventeen recent species which are primarily diurnal animals, often living socially. Generally the senses of sight and hearing seem to be better developed than the sense of smell. Therefore, in terms of communication, acoustic and optical signal systems have prominent importance.

Chemical Transmission of Information

Dermal glands in this group are but poorly developed. In Equus circumanal glands may serve in the chemical transmission of information in reproductive behavior; the perineal glands have also been described for this species (Schaffer, 1940). Besides, there are carpal and tarsal glands in Rhinoceros unicornis which perhaps leave a specific scent on the trial as has occasionally been pointed out (Gee, 1953). In addition, Equus has circumoral glands the significance of which seems to be unknown; they may function in oral contact. In territorial behavior, however, defecation and urination are significant. In Equus burchellis, the stallion smells urine and dung areas and then deposits its own feces there. In Diceros, after defecating, the males paw, thus spreading the dung. Paths are also marked by Rhinoceros “depositing its dung in the same spot, until a pile accumulates” (Gee, 1953, p. 771). This is not a case of individual marking; each animal which uses the trail deposits its dung. Specific trails are used again and again for a long time. Similar facts have been described in Ceratotherium simum (Backhaus, 1964; Fitzsimons, 1919-1920; Player and Feely, 1960).

Mechanical Transmission of Information

In Perissodactyla acoustic communication is performed chiefly by means of high-frequency sounds (Tapirus, Diceros, Rhinoceros, Ceratotherium). Beginning with Equus, lower frequencies are added, since specific sound sequences develop here (strophic, heterotypical). In the Rhinocerotidae low sound patterns (roaring, rumbling) seem to function primarily for defense (W-eliciting sounds). Tapirus evidently does not possess sounds of lower frequencies, disregarding “grunting,” which is said to be uttered by males during rut (Schneider, 1935). The main types of sounds in Tapirus are the whistle and polysyllabic calls (mostly bisyllabic), which transmit species-specific and possibly individual information also (Hunsaker and Hahn, 1965; Tembrock, 1963).

In Rhinocerotidae one may distinguish the following types of sounds: grunting, snorting, panting, wheezing, whistling (= piping, =squealing, = squeaking), screaming (young animals), short sounds, growling, roaring (Kasbohm, 1964; Ullrich, 1960, 1962). Little is known about the functions; during “greeting,” rhythmic forms of sounds (“bubbling”) have been heard (Ullrich, 1962). The short sounds are uttered most frequently, and they seem to serve voice contact within the group. In Rhinoceros unicornis they have frequencies between 320 and 900 Hz (main frequencies about 320 Hz), in Diceros the main frequency is near 540 Hz. Rh. sondaicus probably has short sounds similar to those of Rh. unicornis (Gee, 1953; Lang, 1961, Sodi, 1959; Ullrich, 1962). For Dicerorhinus sumatrensis “a noise something between the bark of a dog and the quack of a duck” has been described (Hubback, 1937, p. 77), which has been heard during the smelling of strange scents. A high, whistle-like sound, which has been compared with the calling of Hylobates lar, is probably the voice-contact sound in this species also. In Equus przewalski (and caballus), generally five groups of vocalizations are differentiated: neighing, screaming, squealing, snorting, and sounds of the stallion during courtship. Neighing represents a heterotypical, strophic sound sequence, which has special functions of communication, among these, certainly individual-specific characterization. It has also been assumed that horses utter specific variants of neighing which are directed toward specific individual horses (Hauck, 1928; Maday, 1912) since frequently only specific individuals answer the neigh. It is a general rule that strophic, structured sound patterns are especially preadapted for individual characterization. In addition, neighing shows sex-specific differentiation. Functionally, three forms of neighing have been distinguished: high, loud, long (voice contact between mother and foal); deep, low, short (near contact with a conspecific); and deep, loud, long (rut call of the stallion); yet these distinctions need more detailed study. Neighing also has been supposed to be a “distress call” (Hauck, 1928; Maday, 1912), as well as an acoustic enhancement of the “greeting face” (Trumler, 1959). Snorting is assumed to be a danger call, but the function supposedly differs depending upon whether it is given singly or once repeated (Marler, 1959). The function of screaming, which is not only uttered in pain (Maday, 1912) is not clear; perhaps it is employed in defense. This may also be the case with squealing, which is frequently connected with kicking the hind legs. Groaning is a sound made by the stallion during rut and often connected with the stomping of one foreleg. The noisy blowing of intestinal gases during defense (or flight) seems to have an acoustic signal effect and seems to influence the behavior of other individuals.

Some of the sound patterns mentioned here are also characteristic of other species of the Equus group; most differentiated by species are the call sequences, which evidently also carry the highest content of information and which, during evolution of the communication mechanisms, are subject to stronger selection. Whereas in Equus burchelli these call sequences represent relatively simple strophes, in E. zebra, E. grevyi, and, finally, in E. asinus and E. hemionus they are highly differentiated and also substantially longer. This is probably related to the mode of life, species-specific forms of communication, and social relations. The increasing incorporation of sounds with lower frequencies into the primarily high voices of Perissodactyla is significant. This may be related to the superposition of A-eliciting tendencies (sexual behavior, social contact) and W-eliciting (defense) tendencies. Experiments employing dummies in Equus asinus indicate, indeed, that particularly the high components of call sequences release approach behavior and calling. In E. g revyi a strong sexual dimorphism seems to exist; it is not known for certain whether the mares neigh at all (Anthony, 1928). They use deeper, short sounds during defense. On the whole, within the interesting Equus group, many questions still remain about the relationship between differentiation of the sound pattern and the information conveyed.

Optical Transmission of Information

The behavior inventory of Perissodactyla, especially Equidae, is rich in optically effective signal systems, though in many cases the specific functions have not been well defined. The principles of display are similar in many aspects to those of Carnivora. Additionally, various signal actions of both orders may be compared, and this may point to a possible phylogenetic explanation.

Somatic Motor Patterns. In Perissodactyla, movements of the torso usually have only inferior signal functions, and even then mainly in connection with other coordinations. In an intimidating display, the whole torso may stiffen (Equidae). The extremities have various functions in terms of optically (and tactually) effective signal actions. This is especially true for the frontal extremities; one of the legs may be lifted to strike (intention movement). From this (as in Carnivora) the lifting of both forelegs off the ground (dancing), a demonstrative movement in agonistic behavior and during rut which has strong optical effectiveness can be derived. The countermovement is kicking with both the hind legs, which also occurs as a demonstration movement. Specific positions of the tail have signal function: the rutting mare lifts the tail at the root horizontally and probably in most cases bends it somewhat laterally. The dermal muscular system offers the basis for a partial twitch, which primarily serves in the defense against parasites (protection behavior), but which may also be significant as signal movement; details, however, have not been examined. Pawing and rolling may also have a function in intraspecific interchange (Tembrock, 1964). Ritualized pawing seems to appear, chiefly, if Aeliciting (distance-decreasing) tendencies are checked. Again, particularly in Equidae, several paces can become ritualized signal movements executed demonstratively in a specific manner. Rapid flight movements signal to conspecifics a corresponding behavior (“Estampeda”).

Visceral Motor Patterns. Signal movements in the head and neck region are very pronounced in all Perissodactyla; especially those having lateral effectiveness which have developed due to the position of the eyes: lifting of the head, lowering of the head, and nodding. The mane, as a signal structure of the Equidae, may greatly support the effectiveness of these modes of behavior. In Tapiridae the movements of the “trunk” also seem to have a signal effect. In Rhinocerotidae, face-to-face interchange (i.e., combat), appearing elsewhere only in Artiodactyla, has developed through evolution of the head weapons from the face-to-face position and lowering of the head. A specific expressive movement in agonistic behavior is the lifting and the simultaneous lateral turning of the head which checks the aggression of the rival. Movements of the ears doubtless have high signal value which in Rhinocerotidae may be modified to peculiar rotating movements (agonistic behavior). The functions of the teeth in communication are also manifold. They may be an immediate fighting weapon (especially in Equidae); here the fight is often combined with movements of kneeling on the forelegs՝, where the forelegs are special targets for biting. Various combinations of lip and jaw movements offer rich nuances of expressive behavior (Trumler, 1959, fig. 22). In Equidae social grooming is also ritualized, whereby a mutual nibbling at the neck and shoulder region is characteristic. In Equus zebra, E. burchelli, and E. g revyi the complex patterns of the design of the coat may also serve individual characterization. Experiments employing dummies have proved that coats are sufficient to release species-specific communication behavior (Grzimek, 1960; Trumler, 1959).

ARTIODACTYLA

This order contains 9 recent families with 82 genera and about 200 species. They inhabit very different environments and are also quite distinct in terms of size and way of life. Hence, for the large groups, the principles of communication are rather dissimilar in nature.

Chemical Transmission of Information

In Artiodactyla numerous dermal glands, through secretion, serve for chemical signaling. In Dicotyles the dorsal gland has been known since 1683 (Schaffer, 1940). It has developed in both sexes and is located on the back, about eight inches before the root of the tail. In one instance, musk was ejected for about one foot. Adult animals were observed rubbing each others scent gland (Neal, 1959). During mating behavior, the male rubs the female’s scent gland with its nose. Musk also seems to be a danger signal. Perhaps the composition of the secretion changes, and in that way different information is transmitted. A conspicuous dorsal gland can also be found in Antidorcas. In Capreolus, the buck has a frontal gland between the antlers (Raesfeld, 1956; Schaffer, 1940) which has two components; one reaches its peak of activity before rut, and the other one becomes fully active only during rut. From this it has been concluded that there are different types of secretions. The buck of the roe marks his territory several times a day by rubbing the front of the head against stems and branches. In Capreolus, additional scent glands exist at the hind legs and between the toes of the hind feet. These pedal glands have also developed in other Cervidae and through them a specific trail scent is generated. At the frontal side of the hind foot a secretion, different from the one on the dorsal side, will be ejected. Thus, chemical information about the direction of running may be transmitted. Similar interdigital glands, frequently in all four feet, are found in almost all Artiodactyla (Schaffer, 1940) despite rather different development in detail.

Carpal glands have been found in Suidae. Potamochoerus has digital glands. Other glands of significance in Artiodactyla are the preorbital glands, the secretions of which are deposited on twigs and the like (Bourlière, 1954; Hediger, 1949, 1951; Schaffer, 1940). The retrocornual glands have similar functions; in Rupicapra, these glands function in the buck only during rut. Inguinal glands as well as anal and circumanal glands are widespread. In Cervus there are also circumcaudal glands. Hence, there are in Artiodactyla various means of chemical information transmission, yet these have not been studied sufficiently, particularly with regard to the chemical composition of the secretions and their specific functions.

Cervus elaphus canadensis and Odocoileus mark their territory by scraping the base or burr of the antler against the substratum to be marked. “Such signposts may serve by intimidating strangers entering such marked territory” (Graf, 1965; Lindsdale, 1953; Wynne-Edwards, 1962, p. 104). Afterward, they rub the sides of the muzzle and chin on the post, as well as the flanks. Circumoral glands may function here. In Moschus there is a gland at the belly, from which a strongsmelling secretion is ejected during rut. In addition, the Cervidae also have a special gland at the tail. Finally, there are circumanal glands. Unfortunately, nothing is known about the specific functions of these three groups of glands.

In many Artiodactyla, urine and feces seem to serve the chemical transmission of information. Bison bonasus rolls in urine and afterward rubs against certain trees, thereby marking its territory. Bucks of Ammotragus lervia use their horns to throw soil, drenched in urine, on their backs (Hediger, 1949). Many Cervidae “wallow” in urinesoaked pits. C hoer opsis uses urine and feces for scent marking, whereby the brush-like tail is brought into swirling movement and urine and feces are mixed and spread. The females do not show this behavior. In Hippopotamus likewise, through swirling of the tail, feces and urine are used for marking; occasionally old bulls may direct this behavior toward the heads of intruding rivals (Hediger, 1951). Tylopoda of the new world have a certain “feces ritual”: first, they smell the feces spot (which is fixed), then stamp upon it with the forelegs, then paw, and afterward defecate directly upon it (Pilters, 1954). A similar behavior has been observed in Ourebia. It has been described further in Antilope cervicapra, Gazella bennetti, and Boselaphus tragocamelus. Most males of Artiodactyla sniff deeply the urine marks of females. In connection with this, many species show an action which has been called “Flehmen” (lipcurl: lifting of the head, shutting of the nostrils, lifting of the upper lip) and which probably represents an olfactory control of the scent substances by means of the Organum vomerale. Phacochoerus has developed a “urine ritual”; on this occasion the female urinates, the male partly picks up the urine, then scents the spot, licks at it, shakes the head, and afterward marks by squirting its own urine (Frädrich, 1965). Ammodorcas clarkei also marks by means of urine (Schomber, 1964).

Specific forms of behavior are connected with the chemical transmission of information between animals. The two main types are nasonasal testing and naso-genital testing (Schloeth, 1956). Probably in most of the Artiodactyla, the mother distinguishes her own young in this way. Optical and acoustic information may also play a part here (Blauvelt, 1954; Blond, I960; Tschanz, 1962).

Mechanical Transmission of Information

The acoustic transmission of information in Artiodactyla has developed to different degrees. Species which live in places of dense and high vegetation possess more differentiated sound patterns than species living in open landscapes, in which optical information prevails. The Suiformes, many species of Cervidae, most Bovini and Caprini have differentiated vocalizations. Generally it may be said that in other groups, especially the Giraffidae, Strepsicerotini, Boselaphini, Hippotraginae, and Antilopinae, vocalization has undergone secondary regression because of the strong development of visual communication. Also, some groups such as the Cephalophini and a series of rare species in the Caprinae have been little studied.

In Suidae three trends in differentiating vocalizations seem to be significant in the development of information transmission: (1) transformation of (probably primary) short sounds to long sounds, (2) adding rhythm to the short sounds, and (3) transformation of the frequency range.

Tendencies to socialize promote the differentiation and frequency of vocalization, since they serve to maintain general coherence in dense environments. In Potamochoerus choeropotamus these sounds have very low frequencies (main frequencies between 60 and 200 Hz). Sounds which release the active approach of a member of the species have high frequencies (squealing) and may be derived from the sounds of piglets which thereby activate caring behavior. Probably individual information may be transmitted via the frequency range. In Potamochoerus poreus the frequencies seem to be a little higher than in P. choeropotamus. In Sus one may distinguish the following forms of sounds (Grauvogel, 1958; Hainard, 1949; Snethlage, 1957): sounds of hunger, sounds of pain, defense sounds (“growling”), warning sounds (“barking”), defensive sounds (expelled sounds), voicecontact grunting, place sounds (short sounds, announcing the place), sounds of discomfort, rut sounds, luring sounds (of the nursing sow) and, in addition, special “milk sounds” (three types—during the letdown of the milk, during the flowing of the milk, and when the piglets cease to nurse) (Gill and Thomson, 1956). Some typical sounds of the piglets which release a certain nursing behavior in the mother have to be added. Furthermore, noises of the jaws are heard, especially in the rutting boar. Its rhythmic rut sounds have been proved to have the function of immobilizing the female so that mounting becomes possible (Signoret, 1960). The same behavior may also be released by acoustic dummies, and therefore they are used in practical breeding.

In Suidae, besides voiced sound utterances, teeth grinding and voiceless sounds—panting and pufflng—occur; the latter always seem to be warning or threat signals (Hainard, 1949). In Pecari tooth-clapping appears to be used for aggressive threatening, in Phacochoerus it is connected (strongly rhythmic) with expelled sounds in the boar during mating behavior. It might have been developed by ritualization of aggression sounds, as the mating behavior often includes such components; also, Phacochoerus is not as likely to vocalize as other Suidae (Frädrich, 1965), for instance, Hylochoerus (Frädrich, 1965) or also the Tayassuidae (Neal, 1959). In Tayassus albirostris the main frequencies of the voice contact sound are between 80 and 150 Hz. Here, the warning sound is also a bark-like sound, uttered once.

The Hippopotamus are decidedly territorial (Bartlett, 1871; Hediger, 1951; Verheyen, 1954). They make voice-contact calls and, above all, a strophic, heterotypical call sequence, which probably serves to characterize both territory and individuals. Bulls often utter sounds after marking by means of defecation. Neighing has been taken for a warning sound and has been said to occur during inhalation. Panting sounds (in close contact) also appear. Finally, roaring serves to announce ownership of territory and, at the same time, is an aggression sound (also called “grunting”) which will be uttered only within the bull’s own territory. In Choerocsis the main frequencies of the voice contact sound lie between 200 and 700 Hz (yet with high overtones up to 2500 Hz). In this species little else is known about specific sounds.

In Camelus the following sounds may be distinguished: roaring (primarily voice contact, shortened and expelled—defensive, ritualized during rut), “gobbling” and “bubbling” in connection with the turningout of the throat pouch during rut (rhythmic!); bubbling is said to appear also as an intimidation signal (Pilters, 1954, 1959). Growling serves as voice contact between mare and foal, bleating as a call for the foal when it is out of sight. Mechanical sounds are made in spitting and in grinding the teeth; stamping also occurs (Pilters, 1954, 1959). In the genus Lama the vocalization is also rather differentiated; neighing call sequences (Lama guanacoe) warn members of the species; bleating serves for voice contact (often repeated); growling and gargling have W-eliciting functions (agonistic behavior); moreover, there are still other partly voiceless noises (smacking, panting), and rut calls.

The most significant communication sounds in Cervidae are rut calls of the stags (long sounds) which have territorial functions, rhythmic sound sequences during herding, piping sounds which release approach in conspecifics (young ones, females), warning calls which mostly sound like barking and generally are uttered in both sexes (for instance Muntiacus, Capreolus, Cervus, Dama) (Donath, 1960; Hennig, 1962; Kirchshofer, 1958; Raehfeld, 1956).

Defensive and threatening sounds, above all tooth noises (in connection with the original use of teeth as a weapon) and squeezed long sounds (Odocoileus) or a threatening hiss (Cervus, Odocoileus) are all additional vocalizations. In Alces “acoustic intimidation” has been supposed (Geist, 1963). Predominantly females in several species utter bleating short sounds, which are often repeated (very typical in Dama dama); perhaps they serve the individual characterization of the mother. Stamping in Cervidae is very typical (when ritualized, particularly during rut, as in Axis procinus, Muntiacus, Alces) (Brommee, 1940; Donath, I960; Tembrock, 1963). In Cervus elaphus, the subspecies differ in their rut call (really a territorial call) by an increase in the main frequencies from Europe to North America (Cervus elaphus canadensis) (Tembrock, 1965). Certainly these calls serve to characterize the individual also, yet experiments which would demonstrate this have not been done.

Voice contact between the young and the mother also has been described in Okapia in which only a few types of sound are known (Gill and Thomson, 1956; Lang, 1957), though there probably are some acoustically effective modes of communication here, and also in Giraffa (Backhaus, 1961; Innis, 1958). In the Bovidae generally certain “bleating” types of sound seem to represent the bases of communication; by transforming length and frequency, as well as rhythmicity, different signal values may result. The so-called “roaring” of cattle should be included here. In Caprini, finally, this type of sound is modified by a velar component or expelled phonation, resulting in “bleating” (vibrating sound). Rhythmically strophic sound sequences are not rare, and they seem to serve above all to announce territory, to further the characterization of the individual, and often in reproduction behavior in which they are uttered particularly by males [for instance, Antilope cervicapa, Tragelaphus (Walther, 1964); Connochaetes (Schneider, 1956-1958), Ovis, Bos]. Cephalophus sylvicultor, by imitation of the luring call, may be induced to mount (Zwilling, 1950). Oreotragus utters a signal whistle as a warning call (Shortridge, 1934; Stevenson-Hamilton, 1950) and similarly Ourebia (Malbrant, 1949), whereas Hippotragus also snorts (Erbach-Fürstenau, 1912). In Connochaetes g nou the warning sound is a voice snorting (long sound). In Antilope cervicapra the mother probably identifies her fawn by scent, but the fawn recognizes its mother by voice [frequency range (Seton, 1909)]. Rupicapra has a bleating voice contact sound, whereas whistling in most cases is interpreted as a warning sound (Couturier, 1938). In Capra ibex the whistle is also a warning sound (Fehringer, 1953; Hainard, 1949). In Ovis ammon musimon the nature of the voice contact sound is in between sheeplike and goat-like bleating. During agonistic behavior, the booming sounds are characteristic (Ovis); warning sounds may also be combined with stamping of the foreleg. For Bibos gaurus functionally different sounds have been distinguished (Holzapfel, 1939): snorting (warning), whistle-snorting (aggressive threat), voice-contact sounds (mother and young), and contact sounds (between adult conspecifics).

The Camargue cattle has the following functionally differentiated types of sounds: roaring (call sequence, territory announcing), herd call, urgency sound, bawling (mother separated from the calf), bleating (calves: voice contact with mother), booming (intimidating sound of the bull), when modified booming serves as a fight or chasing sound, rut sound (grunting), play sound of the calves, and guttural grunting, used by cows toward calves in their visual range (Sanderson, 1956; Schloeth, 1958, 1961).

Similar differentiations exist in the other cattle forms, though there are specific race variations. Generally, the domesticated forms are more likely to produce sounds than the wild forms. The homologous calls in Bos grunniens and Bison have very low frequencies which sound like grunting. Bison bison (bulls) during rut utters a loud roar, apparently as a sound sequence which here probably has territorial functions (Fuller, I960; McHugh, 1958).

Tactile stimuli, even though as yet little studied, are of great importance in the communication of Artiodactyla. Included here are the numerous variants of contact by antlers and horns and also social grooming (licking, nibbling, and playful biting), biting, pushing with the muzzle, picking up, shoving off (for instance, Phacochoerus, Frädrich, 1965). The touching and beating with one foreleg (Ovis, many Hippotraginae) also belong here (Marler, 1959; Schomber, 1963; Tembrock, 1964; Walther, 1959-1960, 1960-1961, 1963, 1964, 1965).

Optical Transmission of Information

The various types of antlers and horns, which in most cases have undergone sex-specific development, are doubtless signal structures. In addition, there are many differentiations on the surface of the body, especially with regard to mane, color, and design pattern; in some species the teeth are enlarged also (Moschus, many Suidae).

Signal actions have been developed to high optical effectiveness particularly in those species in which the eyesight dominates.

Somatic Motor Patterns. Several movements of the extremities have been ritualized and have become signal actions. Kicking with the hind legs is rare in Artiodactyla; it does not exist in Tylopoda and Giraffidae; in Antilopidae it may still appear as a “caper” (kicking out while jumping, Walther, 1960-1961). Beating with the forelegs occurs in two ways: the leg is lifted and then struck down upon the adversary or the blow is delivered as the leg is being raised (kicking); this primary fighting behavior also may be ritualized and become an optical signal action. Relations to this behavior can be found in the “excitement-stamping” of the Cervidae and Caprini, and in the threatening pawing of Gazella, Oryx, and other species (Walther, 1960-1961). But threatening pawing may also be derived from rest behavior (pawing before lying down) as in the Bovini, Hypotragini, Caprini (Tembrock, 1964). The raising of the upper body, as in the threatening jump and fighting ritual of Caprini (for instance, Ovis polii, O. cycloceros, O. canadensis, Capra ibex, C. falconieri, Hediger, 1961; Walther, 1960-1961), can probably be derived from certain movements of the forelegs (lifting).

Certain intimidating postures and movements with lateral effectiveness (standing at an angle to the rival) are characterized by certain positions of the torso (for instance, hunch) and in some species by stiff, slow movements; the tail is often stiffly stretched (Boselaphus); in the mating ritual certain stretching positions are often characteristic (Walther, 1960-1961). Kneeling down may appear as a signal movement [Suidae, Connochaetes and others (Frädrich, 1965; Tembrock, 1964)].

Visceral Motor Patterns. Connected with the described intimidation movements are specific positions of the head which in most cases show relationships to species-specific fighting behavior. There are three fundamental types: lifting of the head (for instance, Lama. Antilope cervicapra), horizontally stretching forward of the head (for instance, Boselaphus), and lowering of the head (for instance, Bos, StrepsicerosÎ, Tylopoda). In Hippopotamus lifting of the head is connected with a yawning movement; here, the gases of the 14 sections of the stomach are mainly emptied through the muzzle (Hediger, 1949; Verheyen, 1954).

Lifting the head may often be connected with baring the teeth (Cervidae), and certain color and design patterns may also have great optical effectiveness (Antilope).

Some of such optically effective signal movements may possibly be derived from “neck-fighting” (Backhaus, 1961; Walther, 1960-1961), as it is characteristic, for instance, of Giraffidae, Boselaphus, Tylopoda, and some other species.

Vegetative Motor Patterns. Here the previously mentioned yawning of Hippopotamus must be included, as it is combined with visceromotoric movements. Some gland secretions may also become optically effective by means of strong discharge, and changes in the pupils probably produce optical signals, but here again, these have not been studied.

* A-eliciting = approach eliciting; W-eliciting = withdrawal eliciting (see Schnierla, 1959). The author has agreed to the translation of “affinen“ and “diffugen“ as A-eliciting and W-eliciting sounds, respectively, although his interpretation does not quite coincide with that of Schnierla’s A/W theory.

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