FAMILY: TENRECIDAE

2 subfamilies with 9 genera comprising 29 species. Madagascar and adjacent islands.

Most tenrecs do not display any deep-rooted grouping tendencies. They live a solitary existence, well dispersed within their environment. Single species, especially the lesser hedgehog tenrec (Echinops telfairi), can sometimes be found in twos and threes, but it is not certain whether these are merely the remaining members of mother-young units. The streaked tenrec (Hemicentetes) is the only tenrec genus in which we find colony formation. Hemicentetes, whose equipment for acoustic communication is the most specialized and best developed among tenrecs, has a special stridulation organ in the mid-dorsal region. Since a similar organ has not been developed elsewhere other than among juvenile specimens of the tailless tenrec (Centetes ecaudatus), the genus that produces the largest number of young among recent mammals (up to 32 in one litter), it is obvious that the acoustic interspecific method of communication is linked with the more gregarious way of life led by Hemicentetes and Centetes.

The perineal drag used for leaving chemical scent markings seems to be prevalent in all species of tenrec. The same is true for gaping with the mouth as an optical form of communication. Furthermore, the varied use of ultrasonics in communication is remarkable, as is the complex function of the white secretion produced from specially developed glands situated in the eyelids. This has been the subject of closer study in Setifer, Echinops, Microgale dobsoni, and Microgale talazaci and is adjudged to be, among other things, a form of chemical communication (Poduschka, 1972b, 1974b).

Optical Communication

Whether the erection of the prickles, bristles, or quills, peculiar to all Tenrecinae when aroused, is an optical signal is not clear. It could be a sign of defense posture, similar to that among hedgehogs, especially since a conspecific only reacts to it when it is accompanied by acoustic signals. As a result, we can say with some degree of certainty that it is used as an interspecific optical threat only within a whole communication complex containing acoustic, possibly optical, and almost certainly chemical forms. Intraspecifically it can be the equivalent of a threatening gesture designed through the erection of the prickles or bristles to make the animal appear larger and, therefore, more capable of successful defense.

When a female greater hedgehog tenrec (Setifer setosus) is willing to mate she lifts the perineum from the ground while simultaneously curving her spine concavely downward (lordosis), thereby presenting an unmistakable optical mating signal, which could possibly be strengthened by the emanation of chemical stimuli from the perineal glands, but which is understood visibly by the male (Poduschka, 1972a, 1974a).

The eye-gland secretion, described in more detail in several specific papers, could in certain circumstances act as an antipredator mechanism: the dazzling white patches that suddenly appear when the animal is excited or afraid, in place of the tiny and inconspicuous eyes, could possibly aid a nocturnal or crepuscular creature to scare off a predatory enemy.

Tactile Communication

As nocturnal or crepuscular animals, Tenrecidae possess long and numerous vibrissae (Fig. 2). They appear, however, to be used only for orientation and not in tactile communication. In an encounter other forms of communication are used. In the marsh tenrec (Limnogale mergulus), the only semi-aquatic form of Tenrecidae, we find—presumably as a kind of practical adaptation for life in water—the same numerous vibrissae on the snout as among the equally semi-aquatic Talpidae Galemys pyrenaicus and Desmana moschata; these vibrissae increase uniformly in length the further they sprout from the tip of the snout, and they are innervated by unusually strong nerve cords. There is no doubt of their primary use as sensory tools (Bauchot and Stephan, 1968). Whether they have a communication value we cannot say, since nothing is known about the ethological details of this species, presumably the rarest of tenrecs.

Fig. 2. Adult male Setifer setosus. The facial vibrissae extend far beyond the body width.

During the courtship behavior of all the Tenrecidae studied so far (tailless tenrec, streaked tenrec, greater hedgehog tenrec, lesser hedgehog tenrec, microgale dobsoni tenrec, microgale talazaci tenrec), there occurs a ritual nestling up to each other with those parts of the body that have concentrations of glands. Here the nose-tonose, nose and eye area-side, nose-anal/genital contact is merely the beginning of the ritual, or rather the most stereotyped form. Following it, the male and female tenrec rub their sides against each other or crawl over and under each other. All this indicates a combination of tactile communication with stimuli from gland areas in the partner; in addition there is an individual olfactory-chemical stimulus caused by the animal's own secretions, which could be considered a feedback system.

The mounting that follows is soon accompanied by the male's scratching the female's sides with his hind legs, aimed at stimulating her, which acts as a release mechanism for the presentation of her perineum. The male avoids a premature release from the mating "tie" (lasting in Setifer for more than two hours, presumably because of the strong accessory erectile tissues in the penis or by an intravaginal retention of the vine-shoot-like glans penis: Poduschka, 1974a) by allowing his hands to rest on the female's sides during the whole tie period. If he gets tired and slides off, he rests his hands on her back. Whenever the female tries to break away from the tie position, the mere hint of a grasp from the male, which is never so firm that the female cannot escape, is enough to indicate that the tie between the genitalia is not yet broken.

During courtship the male lesser hedgehog tenrec repeatedly bites the spines on the female's side. By doing so he seems to stimulate her readiness to mate. This pattern is even more clearly and efficiently developed among the greater hedgehog tenrec: every time the female tries to escape—which is part of her mating ritual—she is held back by the male's energetic biting into the sagittal lower region of her back and drawn back to him again (Poduschka, 1972, 1974a). This bite is not identical with the copulation bite, which, among Setifer at least, is not meant to keep the female still so that mating can take place but is only delivered when intromission has already taken place, in order to improve the lordosis of the female. This bite is therefore a tactile signal, to which the female responds by trying to evade the copulation bite. As she slips away, she raises the perineum, thus improving presentation and the tie of the genitalia (Fig. 3).

Acoustic Communication

All tenrecs possess a large and varied repertoire of signals, which seems all the more remarkable when tested by an ultrasonic receiver. Throughout its whole lifetime the streaked tenrec (Hemicentetes) even has a special, mid-dorsal stridulation organ consisting of several rows of specially formed quills, which are moved by special muscles in such a way that signals are produced by the resulting friction. These stridulation sounds show little harmonic structure. They form a broad band from about 2-200 kHz in adult animals. Young Hemicentetes produce stridulation sounds of lower intensity when they are between eleven and seventeen days old. When they are about seventeen days old the intensity of stridulation is very near adult level (Eisenberg and Gould, 1970). This is a phenomenon parallel to that observed in young Setiferes, where the signals of the young become stronger and higher in the ultrasonic range the older the babies get (Poduschka, 1974c); and certainly very dissimilar to that in young rodents, whose ultrasonic signals are noticeable just after birth, but gradually become softer or even disappear completely after a few days as soon as the meatus acusticus and the eyes are open, but, on the other hand, will continue for several more days if the animals are handled (Noirot, 1968; Noirot and Pye, 1969; Sales, 1972).

Fig. 3. Copulating Setiferes. Note the male's stimulant scratching with the hind foot and the stimulant bite on the female's back.

Hemicentetes stridulates almost continuously when active and on the move. Stridulation occurs while feeding, during social contact, during courtship and mounting, during exploration, when escaping pursuers, or when merely moving away. Generally speaking, low stridulation occurs when the animal is normally active. When the animal is aroused intensely, crest erection occurs (presumably more as a sign of readiness for defense than as an active optical signal) together with an increase in stridulation, which does not remain at a peak but decreases in waves after the excitement is over. It is difficult to decide what can be considered communication with a partner, with young, or with threatening predators, and what can be considered a reaction to the stimulus that caused the excitement.

When foraging, young Hemicentetes move about nine to ten feet away from the mother, who keeps them close to her by stridulation. Thus, stridulation serves in the mother-young unit not only to identify the female's whereabouts (Eisenberg and Gould, 1970), but also to indicate to the mother where the young are, since they too are able to stridulate.

Young tailless tenrecs also possess a stridulation organ in the mid-dorsal region. It is not such a specialized one, however, and it disappears during individual ontogenesis. It consists of two rows of white spines, which by means of a special dermal musculature vibrate together and produce sounds. Some of these spines may remain in the subadult animal and still produce signals but they are gradually lost and do not get replaced (Gould, 1965). Gould was also the first to find out that stridulation among young tailless tenrecs, a pulsating sound varying in intensity between 12 and 15 kHz, is associated with high levels of excitement, and keeps mother and young together.

It is probable that stridulation was originally a warning signal to a predator but later became an interspecific signal indicating position. Stridulation in Centetes is different from that among Hemicentetes. Here stridulation occurs in conjunction with crest erection and erection of the center quills and a simultaneous hiss from a half-open mouth. Stridulation seems to occur when there is the inclination to attack coupled with an equally strong inclination to withhold. It was also found that stridulation serves as a warning signal to other members of the group, resulting in arousal and attentiveness. It may also indicate the identity and position of a juvenile that has been startled. It could also help in the location of the young by the mother and/or the location of young by other young. The exact function is unknown (Eisenberg and Gould, 1970).

Echolocation in tenrecs has been proved to exist among Hemicentetes, Echinops, and Microgale dobsoni. Contrary to the obvious assumption, stridulation is not essential for echolocation; the species studied by Gould (1965) echolocate by means of clicks produced with the tongue.

The vocal emissions of Tenrecidae take place mostly within the range of ultrasonics—at least so far as they are relevant for the animals. When they were filtered out, it was noticed that sounds within the human hearing range were of little interest to the animals.

During mating Echinops females utter snapping signals with a frequency of up to 51 kHz and twittering noises up to 37 kHz. These are used not only as a defensive signal in response to the continual insistence of the male but also as an aural threat: Sometimes an unwilling female leaves the nest where she has been urged to mate by the stimulating scratches and mounting attempts of the male; she turns toward him energetically with gaping mouth, and emits these same twittering noises. We can assume, therefore, that these twittering noises serve a number of purposes. Echinops also possess other belligerent sounds, including an unmistakable hiss. Echinops also reacts to the high-frequency signals emitted by its prey, which are thus recognized as allomones. Mealworms crawling over each other produce a sound with a highest frequency of 42 kHz, which is recognized by Echinops as a signal from a well-known prey and which results in a direct search for it.

During mating the greater hedgehog tenrec produces snapping signals up to 83 kHz and squeaks whose strongest sound pressure is between 50 and 60 kHz.

In Gould's (1965) opinion the clicks are produced among Echinops, Hemicentetes, and Microgale by the lips or the tongue; according to my studies of Setifer and Echinops, however, they seem to be produced more by the root of the tongue or the soft palate or in the larynx.

The small, soft-furred Tenrecidae (Oryzorictinae) emit acoustic signals far less frequently. When defending themselves, they are mostly silent and threaten by gaping with the mouth. Many emit squeals or a long squealing trill, a scream, a wail, or a buzz. When an encounter with a strange conspecific occurs, they utter a soft squeaking sound, which in Eisenberg and Gould's opinion (1970) is meant to prevent any aggressive behavior in the possible adversary.

Chemical Communication

Chemical communication in tenrecs is a subject that has hardly been studied exhaustively. Until now only one aspect has been examined in any detail: the white secretion from the lid glands that was described so far among Setifer, Echinops, and the two Oryzorictinae, Microgale dobsoni and Microgale talazaci. This phenomenon can without doubt be observed in most, if not all, Tenrecidae, possibly in various forms or stages of development; its existence is even more probable in the light of our knowledge of at least the anatomical features necessary for communication that are present in several more species than those mentioned above (Cei, 1946). The chemical examination of this secretion, exuded from special eyelid glands, which exist in addition to the lacrymal glands, is extremely difficult since only a very small quantity can be obtained, but some preliminary results are available.

Eisenberg and Gould (1970) have described additional gland areas in Hemicentetes, Setifer, Echinops, and Microgale that emit olfactory stimuli. Their exact nature as far as communication is concerned has still to be investigated in detail. The glands in question are in the axillary, inguinal, head, ear, and caudal areas. A further study of the sternal and possible ventral gland areas is already under way (Poduschka, 1974e, 1974f).

The secretion from the lid glands also has communicative character in certain circumstances, since the exuded secretion gives off a strong and long-lasting smell. The odor is understood by conspecifics, which respond by getting very agitated and eventually rubbing off the secretion now being exuded from their own eyelids and nostrils: quite often they also rub the area around their own eyes on vertical objects but never on the substrate. These scent markings are not to be regarded in the same way as territorial markings used in the defense of the area in which an animal lives, since tenrecs, as far as we know, do not have any territorial possessions. They can serve the purpose of self-assertion on the spot where the animal happens to be at the time, a phenomenon already observed among many mammals and well documented by Eisenberg and Kleiman (1972) and Kleiman (1966).

Even if a male Echinops in an enclosure that is strange to him has neither smeared eye-gland secretion on the wall nor attempted to place sternal markings (see below), has neither defecated nor micturated, another male put into the enclosure with him will become very excited by scent deposits made by the first male—a phenomenon which has not been explained. The second male will attack as soon as he sees the first male, but will not attack a female in the enclosure or one placed there simultaneously with him. This proves the existence of sexually differentiated scent emanations. Besides the eye-gland, sternal, or ventral secretions, others that could help determine the presence of a male conspecific are pheromones in the spittle, the sweat glands, and other outlets in the skin; the breath; or digestion gases. It must be emphasized that it is not just dominant males that mark in this way, a behavior that Ralls (1971) assumes to be the general norm in mammals.

As a form of chemical communication the eye-gland secretion has various purposes and/or functions:

1. Active: marking behavior, warding off adversaries, suppression of own unease in strange surroundings, possible stimulation of the female during courtship through a smell that acts as an olfactory signal. Whether the eye secretion acts as a primer pheromone and induces ovulation by altering the physiology of the reproduction system is still unknown but not unlikely. Induced ovulation is presumed to exist in tenrecs; fertilization takes place within the ovary (Strauss, 1939, 1942). An optical significance of the white secretion among conspecifics cannot be said to exist, since the female does not look at the male during the preliminary and actual mating behavior; it is just as possible to assume that the male is unable to see the female during the actual mating activity since his eyes might be completely covered by the white secretion (Fig. 4).

2. Passive: excitement during mating due to chemical stimuli from the secretion of the partner, also accompanied by tactile and acoustic stimuli. Several other stimuli, e.g., strong pungent odors or the occurrence of secretion during the very last minutes of a tenrec's life are passive reactions, which have no real bearing on communication.

Fig. 4. Echinops during courtship. The male's eyes are nearly completely covered by his eye-gland secretions.

I have been able to observe and film a special kind of communication or marking among the greater hedgehog tenrec. In strange surroundings or when the animal is unsure of itself because of the presence of several strange conspecifics, the upper part of the body is pressed down flat on the substratum and the forelegs are stretched out passively sidewards so that only the hind legs push the body forward (Poduschka, 1974e). To judge from appearance, it is the sternal glands that are being used here (a behavior pattern similar to those of some more-evolved mammals) or possibly the ventral glands, the presence of which has also been discovered in Soricidae and suspected in solenodons. This apparent method of marking can also take place on a three-dimensional object, for example, on a piece of wood in the enclosure: The animal slides over the top so that its ventral surface is pressed firmly on the object. If the lower side of the object is not lying on the ground (in the case of a large branch or bough of a tree) the animal crawls underneath it, and, lying on its back, the animal presses its ventral area against the object to mark it. The suspected secretion must exude from the gland areas in the breast, possibly from those in the throat or the ventral region. The communicative function of this act is not yet clear. Presumably it is similar to that produced by the rubbing off of the eye-gland secretion, but I have not been able to detect any olfactory stimulus. According to Eisenberg and Gould (1970), the streaked tenrec also leaves scent signals not only by means of perineal drag but also through rubbing the venter by extending and flexing the body on the substratum and by twisting the body when lying on its side. All this has definite potential significance in chemical communication.

Chemical communication also takes place among the two Oryzorictinae, Microgale dobsoni and Microgale talazaci, as it does in Setifer and Echinops among the Tenrecinae through markings that exude from the cloacal region. Markings are made by pressing the perineal area on the substratum: while moving forward, the cloaca is repeatedly pressed down on the substratum. In captivity lactating female Setiferes deposit feces and urine in one place in the enclosure. This action is then copied by the young, who also use this spot for defecation. The chemico-olfactory stimuli released by the mother's excrement can thus be considered a kind of communication leading to a closely related imitation (Poduschka, 1974c).

The salivating of the lesser hedgehog tenrec, which Eibl-Eibesfeldt (1965) has interpreted as a form of marking behavior, should not be considered as such, but rather as the last link in a chain of actions that reaches its peak in the registration and identification of smells and tastes in the vomeronasal organ. It is thus an equivalent to the self-anointing of the hedgehogs, which, like Echinops and Setifer, possess an actively functioning vomeronasal organ. Similar to that of hedgehogs, this behavior pattern takes place only when a strange smell or taste has been detected by the animal, and therefore it has no relevance to any active communication process of its own. This salivation also occurs among Setiferes, and as far as communication is concerned, it is only a reaction to an extraordinarily strong and stimulative allomone (Poduschka, 1974c).

Otter Shrews

FAMILY: TENRECIDAE; SUBFAMILY: POTAMOGALIDAE (OTTER SHREWS)

3 genera. West to East Africa.

There is hardly anything known about the communication behavior of these animals. The lesser otter shrew (Micropotamogale lamottei) in captivity sometimes emits a high-pitched, sharp, loud scream at intervals of about 2 sec (Kuhn, 1964). These acoustic signals have unfortunately never been measured or recorded. Judging from the results obtained from the study of other insectivores, especially the closely related tenrecs, we can assume that these sounds contain ultrasonic components that are important for interspecific communication.

The eyes are remarkably small and presumably have little communicative significance. On the other hand, the vibrissae are very numerous and extraordinarily well developed. Even in the newborn we can clearly see the sinus hair warts from which the strong vibrissae protrude. When the animal is resting, these vibrissae point backward, but they can be spread out sideways and forward when the animal is attentive, even when it is just a few days old (Vogel, pers. photos). Among adults rhythmical movements of the vibrissae backward and forward can be detected (Kuhn, 1964).

Among the Ruwenzori otter shrew (Mesopotamogale ruwenzorii) the use of specific defecation areas has been reported (Rahm, 1961), which could possibly have communicative importance.

According to Cei (1946) the big otter shrew (Potamogale velox) possesses special glands in the lids, which are presumably equivalent to those studied in Tenrecidae (Poduschka, 1974b). It is questionable, when one considers the otter shrew's semi-aquatic way of life, whether they have similar functions. Among Tenrecidae their communicative functions are limited to the emanation of individual- or at least sexually specific smells and to possible visual signals aimed at warding off inter- and intraspecifics.

Solenodons

FAMILY: SOLENODONTIDAE; GENUS: SOLENODON

2 species. Hispaniola: Haitian Solenodon (Solenodon paradoxus); Cuba: Cuban Solenodon (Solenodon cubanus [Atopogale cubana, sensu Cabrera syn.])

At present we are still not in a position to distinguish between the behavior patterns of the two species. The Cuban form was considered extinct several times during this century, but according to the latest reports, this is untrue.

Thanks to the work of the late Erna Mohr, who was lucky enough to be able to keep and observe more living specimens of solenodons than anyone else (fifteen in all), we know relatively much about the behavior of these extremely rare animals. Of course, modern demands for more detailed information extend beyond the scope of the reports she produced at the time. They were restricted for the most part to a phenomenological inventory of behavior patterns. This inventory has in the meantime been complemented by a few ethological works, which I have specified here.

Solenodons are not solitary animals. They have been found in groups of up to eight animals sleeping in the same hole.

Acoustic Communication

Mohr (1936a) has already described the varied repertoire of sounds that the Haitian solenodon (Solenodonparadoxus) possesses. It consists of a "mournful sounding tone like that of kittens prior to the opening of the eyes"; gurgles; shrill screams lasting up to five seconds (?); and a melodious "Strophe," which also lasts a good five seconds, resembling that of a robin. It is often repeated using the same pattern of notes. Möhr assumed at first that this was produced only by young, unweaned animals but later revised her opinion (Mohr, 1936b) when she again heard this Strophe, this time during courtship and mating of sexually mature Haitian solenodons.

Using modern methods of detection, Eisenberg and Gould (1966) registered some chewing and digging sounds also. These were emitted while the animals were walking or running, and were used in particular by the young animals as a source of sound or as a signal to approach. These authors also carried out the first successful ultrasonic tests. My own studies in this field have so far produced varying results, insofar as I have been able, with the aid of a Holgate Ultrasonic Receiver, to detect both clicks with frequencies up to 74.8 kHz and noises produced by the exhalation of breath up to 73 kHz. Of course, this does not prove that these particular signals or their highest components have any relevance for the animals, but it does give some indication: By producing strange noises of a high frequency, which cause solenodons to get very frightened, it was possible to show that this animal is very sensitive to ultrasonic signals between 65 and 75 kHz. The highest components of the emitted signals do not remain constant.

It is also possible to record similar signals of up to 40 or 50 kHz, leading us to suspect varied communicative content. Solenodons are just as sensitive to shrill human voices and loud laughter (Mohr, 1936a) as to mechanical noises with high ultrasonic components (Poduschka, 1974d). Solenodons are able to detect lowpitched ultrasonics well and move toward them, indicating that the ultrasonic signals emitted by insects or small rodents, for example, have interspecific communication value for them. The highest frequencies recorded in the "tuckering" (motorlike) "schnalz" sounds, also mentioned by Möhr, were 28 to 40 kHz. I believe that these sounds are produced mechanically in the larynx or the oral cavity.

The clicks mentioned above can be heard especially when the Haitian solenodon is confronted with a strange conspecific or during the exploration of strange territory. It is not possible to say with certainty whether they are used in echolocation, or as a signal (Eisenberg and Gould, 1966), or could in strange territory be an acoustic parallel, aimed at self-assertion, to the olfactory-chemical behavior pattern of marking already known. These vocalizations of Haitian solenodons are similar to the echolocation pulses of shrews (Gould, Negus, and Novick, 1964).

The Haitian solenodon shows a welldeveloped appetence for nooks and crannies and employs a special kind of breath exhalation when exploring impenetrable cracks and crevices, which could very well be used as a form of echolocation similar to that detected in hedgehogs.

Chemical Communication

According to Mohr (1936b), the Haitian solenodon reveals a pattern of marking during mating or courtship that includes the use of ventral glands. Unfortunately these glands have not yet been studied. The solenodon slides on his ventral area around and alongside the female, pushing himself along with his forefeet and dragging his hind legs behind him. This reminds us strongly of a special kind of marking behavior observed in the tenrec Setifer setosus (Poduschka, 1974e, 1974f), but the solenodon does not press the pectoral area on the substratum; he presses down the venter.

The function of the secernent side glands, which are said to produce odorous substances, has been subject to interpretations that are partially contradictory. So rarely have a male and a female been kept together in captivity that it has not yet been possible to prove that these secretions have any communicative value. According to Mohr (1936b) the side glands only begin to secrete when the animals are six to eight months old; in her opinion the secretion indicates sexual maturity. On the other hand, I have not yet been able to detect any secretion from these glands in a male that was put in with a female after spending five and a half years as a solitary. It could be that the secretion from these glands only indicates sexual activity, which was no longer the case in this particular male—perhaps because of his long period of abstinence or perhaps because solenodon males are sexually active only during the first few years of their lives. The male and female lived together for almost three and a half years, yet never mated. This may indicate that the secretion from the side glands is of essential communicative importance, necessary for the release of a complete pattern of mating behavior in this species.

According to Mohr (1936b) the axillary and ventral areas of adult Haitian solenodons are continually moist. Therefore, glands that could have communicative character must be present. Ignoring for the moment the more abundant material available to Möhr for observation, I must report that I have never been able to detect such an unmistakable secretion in the male and female solenodons I have studied in the past three years. Variations must therefore exist among individuals, conditioned by age or the environment in which the animals are kept.

Fecal deposits are made at random while the animal is on the move. Even in the wild no specially reserved defecation areas have been reported. Eisenberg and Gould (1966) noticed perineal drag immediately after defecation. I have been able to observe and film this only after micturation.

Optical Communication

The only optical signal so far observed among these animals, which live together peacefully with members of their own species and whose tiny eyes and nocturnal habits preclude vision as an important means of communication, is a threatening gesture with gaping mouth. The solenodons were very frightened by an electronic flash. A reduction in the intensity of the flash and the less fearful reaction from the animal that resulted could mean that the startle reaction was indeed the result of an optical stimulus and not of an acoustic one caused by the noise of the camera shutter. I suspect, however, a combination of both sensory impressions (Poduschka, 1974d).

Fig. 5. Adult male Soltnodon paradoxus Note the vibrissae on the head and throat.

Tactile Communication

Since the solenodon leads a nocturnal life, the vibrissae presumably act as tactile organs. They are found in abundance on the head (Fig. 5), where they sprout in especially large numbers on the sides and on the mandible pointing downward, and are also found on the ventral surface, where they stretch from extended embryonic Milchleiste up into the axillary regions. There are also carpal vibrissae, like those found in ground squirrels (Poduschka, 1971). The facial vibrissae can be moved in the skin by muscular movements, which are also referred to by Gundlach (quoted by Barbour, 1944) in the Cuban solenodon.

While observing the communal existence of the male and female solenodon, I have never been able to describe with any certainty a particular behavior pattern as an interspecific act of tactile communication. The animals are quite uninhibited in touching each other with various parts of the body, sometimes vigorously sometimes gently, and seem not to be influenced by the partner while absorbed in their remarkably energetic, continual activities, except that they understand the actions of the partner as an optical signal inviting them to join in or to imitate. They do, however, snuggle up to each other, a behavior pattern common in Tenrecidae and many Erinaceidae; and sometimes they push the nose and cheek area along the partner's body, an action that could be considered the beginning of a tactile communication pattern that changes into a chemical one influenced by the gland concentrations of the partner. It is, of course, possible that this is an action combining both kinds of communication, an assumption made even more feasible by the fact that when solenodons meet they nudge each other with the point of the nose. One pushes its nose into the ears or the axillary areas of the other; that is, into parts of the body that give off strong olfactory stimuli (Eisenberg and Gould, 1966). I have experienced this particular behavior on my own person by a specimen that was especially familiar with me. It seems to me, therefore, to be an integral part of their ethogram.

Golden Moles

FAMILY: CHRYSOCHLORIDAE

5 genera. Southern and eastern Africa.

I have not been able to locate any papers on items of the behavior and/or communication of golden moles. It seems, therefore, that nothing at all is known about these very interesting animals, which, because of their solitary and cryptophile way of life, are very difficult Because of adaptation to to study.

So far only anatomical or taxonomic studies have been produced. The bulbus olfactorius is very large (Stephan and Bauchot, 1960), indicating the importance of the sense of smell. It is questionable, however, whether one can expect to find chemical forms of communication as a result, since olfactory stimuli soon disappear in the dry air of the extremely arid habitat of these animals and cannot therefore be detected easily. Such forms are at least fairly probable, however, within the mother-young unit and indeed are very necessary for these completely blind animals as an indication of readiness to mate.

Results

In the following attempt at a comparative survey of the presently known communication systems of insectivores, I have listed two subfamilies under headings of their own. I want to emphasize that I am quite aware of contravening the normal practice of systematic zoological observation in doing so. This survey, however, is concerned with only one section of ethology: communication, along with the anatomical features necessary for it to take place. It must therefore deal separately with these two subfamilies, since the one differs so completely in its behavior patterns, depending on conditions in its Umwelt, and the other's behavior is virtually unknown.

The first subfamily is the semi-aquatic Desmaninae. Because of adaptation to another medium, the Desmaninae brain differs greatly from that of other Talpidae: modifications include regression of the olfactory centers and enlargement of the auditory, trigeminal, and motor centers. There is also enlargement of neocortical regions, especially of the centers of association. On the whole, there is an increase in brain weight and of the index of encephalization (Bauchot and Stephan, 1968). These differences make it impracticable to compare the communicative behavior and relevant sensory powers of the Desmaninae to those of the other Talpidae.

The second subfamily taken out of its normal systematic context is made up of the five genera of Gymnures (Echinosoricini). So little is known about them that practically nothing can be said about their ability to communicate. Because of the dearth of reports on their behavior, we can merely draw analogies from the study of other insectivores. Nevertheless, we know more about Echinosoricini than about Chrysochloridae. The latter is a zoological family in its own right and ought therefore to be given a rubric of its own, even if it remains unstudied.

When studying the four systems of communication—chemico-olfactory, visual-optical, acoustic-auditory, and tactile—the means by which they are produced, the manner in which they are used, and the anatomical features necessary for their existence, we come across several forms that have parallel, convergent, or analogous functions. In mentioning them we find that a division into completely separate systems is a limitation that cannot be maintained. The discovery, for example, of an actively functioning organ that reacts to two completely different stimuli (the vomeronasal organ in Erinaceidae and Tenrecidae) or of the hitherto unforeseeable complex significance in a few insectivore families of supplementary eye-gland secretions and their functional importance as a means of communication indicates that a combination of various sensory functions can often occur even within the field of communication. This would corroborate the well-represented view that, as a rule, whole complexes of methods are employed in order to achieve communication inter- and intraspecifically. The diversity of these methods and the number of possibilities in combination with others cannot be foreseen. Moreover, we cannot exclude the future discovery of other functioning organs or abilities in insectivores that have long since been discarded by higher orders of mammals or are now present only in rudimentary form and thus extremely difficult to interpret.

In the following tables are listed some of the individual abilities or behavioral patterns that have been found to exist in at least a few genera of the families concerned. The question then arises whether signs of these abilities can be found among other families. Since the data available to us at the moment are still very incomplete, the result is merely an approximate survey of those communication methods common to all insectivores, using the few details that our present knowledge affords us. Because of lack of space some of the details listed in the following tables have not been described in the preceding survey, but they are to be found in various other works on the subject, which in most cases I have listed here.

All the insectivores studied so far emit and react to ultrasonic signals. Five of the nine families (and/or subfamilies) listed in Table 1 emit ultrasonic clicks; four have not been examined. Four use other ultrasonic signals or signals with strong ultrasonic components; in three of them the use of ultrasonics is suspected; two have not been examined. A positive answer to the question of reactions within the human hearing range can be given with certainty only among Potamogalidae, Soricidae, and solenodons; among the others these frequencies seem to be of lesser significance. Echolocation has been observed in Tenrecidae and Soricidae and suspected in Erinaceidae, Desmaninae, and Solenodontidae. To sum up we can say that insectivores are a group of animals that have adapted an ability to detect and emit ultrasonic signals and thus possess the necessary anatomical requirements for echolocation. The question of receptors for the reflected signals has not yet been clarified.

Table 1

We have not yet exhausted the whole repertoire of signals. Their vocalizations seem—generally speaking—to fall into three groups: some combined with inhalation or exhalation through the nose; others derived from clicks with the tongue (Gould, 1969); and others probably originating in the larynx. These three types of sounds are known at present to exist in Tenrecidae, solenodons, and hedgehogs. The continuously emitted sounds, combined with a changing state of agitating and locomotive activity, are rather similar in Hemicentetes (Gould and Eisenberg, 1966; Eisenberg and Gould, 1970), in Suncus and Blarina (Gould, 1969), as well as in Setifer, which emit a series of "put" signals. Tenrec ecaudatus, too, emits a variety of respiratory sounds that are comparable to "puts" (Eisenberg and Gould, 1970). "Put" sounds can also be heard in Echinops and may have the same significance as the low sniffing sounds and low chuckling of a hedgehog that is only slightly agitated.

The broad perspective of chemical communication (Table 2) is too large a field to be treated exhaustively here, since present knowledge has to confine itself, for the most part, to single aspects and single observations of a relatively small number of species.

The deposition of feces as a communication signal is not common to all families and/or subfamilies. On the other hand, the emission of chemico-olfactory stimuli from various glands occurs in all families studied so far. Especially significant seems to be the eye-gland secretion, which apart from its other functions also has communicative character. As far as we now know, it could be regarded as a fully developed behavioral complex; at least the anatomical and histological requirements for such a complex do exist. The exact function of the evolutionary archaic vomeronasal organ has still to be tested in most insectivores. The salivating of Echinopswhich Eibl-Eibesfeldt (1965) has described as marking behavior, is not to be considered as such, but as the last link in a chain of actions that reaches its peak in the registration and identification of a sensory impression of taste or smell in the vomeronasal organ. Just as in hedgehogs, it only takes place after the animal has detected a strange smell or taste and, therefore, it is in no way an active communication signal in its own right. It also occurs among Setifer, where it can be regarded only as a reaction to an extraordinarily strong stimulant or completely new allomone (Poduschka, 1974c).

As predominantly nocturnal or crepuscular creatures with, for the most part, very poor eyesight, insectivores depend a great deal on their tactile abilities (Table 3), which—apart from the vibrissae that are well developed and numerous in all families—have led to the development in Talpidae of especially effective, and apparently extremely versatile, tactile organs on the proboscis (Eimer's organs). Roughly speaking, we can say that the importance of tactile communication is indirectly proportional to the optical ability of insectivores. Investigations have shown that tactile communication is common to all insectivores during courtship. The Tenrecidae occupy a somewhat special position with their unique use of stimulant scratching. Stimulant bites during courtship and mating have been observed in Tenrecidae, Erinaceidae, and Soricidae. The male Soricid offers the female some of his own gland areas for her to bite and thus succeeds in getting her to detect the secretion or at least in transferring some of it onto her body.

Visual gestures or changes in appearance among insectivores (Table 4) are to be regarded for the most part less as active communication systems than as passive reactions to the active stimuli of other systems, since eyesight among insectivores is generally poor. Gaping with the mouth seems to be an action peculiar to all insectivores. In Soricidae, however, we know that it is accompanied by ultrasonic emissions. Whether the remarkable eye-gland secretion of the tenrecs is in fact understood by conspecifics as a visual signal has not been proved either way, but it is certainly of less importance than the chemical message thus conveyed. Lordosis, as a signal inviting intromission of the penis, is common to all insectivores, but presumably even this action is accompanied by chemico-olfactory exudation. Since these animals have such poor eyesight, the odor is much more effective than a visible change in appearance or body position.

Table 2

Table 3

Table 4

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