Mustelidae

The mustelids are primarily small to medium-sized forest-dwelling animals. Many have short legs, long bodies, and powerful jaws. They are among the most carnivorous of the carnivores. As expert predators with stealthy, "slinky" appearances and clever ways, they earn emnity from farmers. Their fur, on the otherhand, is prized. Neither human passion aids their survival. Fur industries in countries such as the United States and the Soviet Union are now raising many mustelids, particularly of the weasel subfamily (Mustelinae: marten, sable, mink, etc.), in captivity and much information concerning husbandry and breeding is being obtained. Field observation of these secretive animals has been mostly unsuccessful. In addition to the afore-mentioned weasel group, there are four other subfamilies including the badgers (Melinae), skunks (Mephitinae), otters (Lutrinae), and honey badgers, or ratels (Mellivorinae). Though the mustelids are found in all continents except Australia, they seem more common in temperate zones. The aquatic otters will not be covered here.

Within the mustelids are found numerous examples of coloration unusual for mammals. Pocock (1908) noted that, contrary to the color patterning of most other mammals, the underside of the body in many of the Mustelidae is darker than the upper, which enhances its con spicuousness. A predatory mammal strives for concealment as it stalks its prey; to do otherwise spoils the success of the hunt. Pocock also discussed the atypical coloration of the ratel (Mellivora capensis), grison (Grisen vittatus), skunk (Mephitis mephitis), and African weasel (Poecilogale albinucha) and its possible adaptive significance in these mustelids:

animals which are coloured so as to be conspicuous in their natural surroundings are very often protected from their enemies by distastefulness arising from a nauseating flavour or odor, . . . which make them dangerous to meddle with. They also as a very general rule have no need of procryptic coloration to enable them to capture wary or keen-sensed prey. Their movements are usually slow and deliberate, and instead of avoiding they seem rather to court observation, some indeed attracting attention by the emission of characteristic sounds. [Pocock, 1908: 945-46]

Pocock countered the notions that the coloring of these species has no warning significance but rather aids them in the capture of small ground prey. "Animals which require sharp hearing either to escape enemies or capture prey usually at all events have large ears; and the fact that the animals forming the subject matter of this paper have small external ears is in keeping with the theory that they have no enemies to fear" (1908:951). The theory Pocock proposes is an interesting one, lending a novel slant to mustelid interspecific behavior. Specifically, Pocock theorizes that the role of mustelid coloration is more one of warning than of aid in prey capture. It reveals the possibility of highly distinctive communicative behavior that sets the mustelids apart from most other carnivores, especially the procyonids and ursids, which are not nearly so vivid in their coloration.

In his discussion of various subspecies of spotted skunks (Spilogale putorius) Mead proposes that behavior and coloration may play another communicative role. "Behavioral differences may also act as isolating mechanisms and indeed lack of, or reduction in amount of, white on the tip of the tail of interrupta may play an important role in 'species' recognition, thereby acting as a barrier to gene flow" (1968:388).

Hall (1974) found that seasonal change to a white winter coat in several north temperate weasels is related to protective coloration. There is an east-to-west band in North America above which all Mustela frenata molt into white in winter and below which all molt brown winter coats.

The use of the anal glands as warning devices is quite characteristic of mustelids. Reports of musky odors can be found for most members of the family. A dearth of behavioral data on the visual, auditory, chemical, and tactile sensitivity of mustelids creates a problem in any attempt to discuss possible communication channels in these animals; unfortunately, this is true also for the ursids and procyonids. Training experiments have shown that both polecats (Mustela putorius: Neumann and Schmidt, 1959) and mink (Mustela vison: Sinclair et al., 1974) have reasonable visual acuity with a resolvable angle of 16.2 and 15.1 min, respectively. This compares with a value of 5.5 for the domestic cat and 20 for the rat (see table in Sinclair et al.). But unlike the polecat, the mink is somewhat aquatic, often swimming deep in water to chase and capture fish. In comparison with the more completely aquatic otters, its acuity in water is about double that in air, suggesting that some mustelids are intermediate or transition species between terrestrial and aquatic environments. Olfaction has been shown to be instrumental in the prey selection and predatory behavior of young polecats (Apfelbach, 1973). A sensitive period for olfactory stimulation apparently occurs between two and three months of age and determines the species of prey to be sought as the animal matures. As for tactile cues, some information is available on young ermine (Mustela erminea). The litter keeps huddled together by fastening their tails to each other ("coupling reflex") until one month of age (Ternovskiy, 1974). This may serve to keep the pups from crawling away when the mother is absent and also to keep them warm, as isolated pups are not able to effectively regulate their body temperature. A role of this behavior in the ontogeny of other types of communication would fit speculative theories such as Dimond's (1970).

MOVEMENTS AND EXPRESSIONS

In most mustelid research reports examples of reproductive, maternal, aggressive, and play behavior are documented, but the precise movements constituting these behaviors have not been delineated with any consistency. While each species may act in certain ways, the exact body movements that signal the intentions are usually unknown. We will report here the types of social behaviors and their expressive components which have been reported for each species.

Polecat (Mustela putorius)

The expressive behavior of the polecat is perhaps the best documented of the mustelids. Ferrets (Mustela furo) are the generally albino domesticated counterpart. Poole's several studies (1966, 1967, 1972, 1973, 1974) have contributed substantially, particularly in describing aggression and aggressive play behavior. Additional information on this species has been gathered by Eibl-Eibesfeldt (1955) and Lazar and Beckhorn (1974).

Play. Conspecific play develops in young polecats after the age of six weeks and the concurrent opening of the eyes (Poole, 1966). Interestingly, the characteristic neck biting, seen especially in aggressive play and prédation, does not develop out of generalized biting; instead, both types of biting occur similtaneously at the age of four weeks. Lazar and Beckhorn (1974) confirmed Poole's observations on the emergence and topography of play in young polecats although they "feel that neck bites differentiate out of general kit biting" (p. 411). Inhibited biting, observed in differences in play with humans and conspecifics, wasdisplayed by these animals. Initiation of aggressive play involved one or more of three techniques: (1) mounting and neck biting until the partner reciprocated; (2) dancing up to and jumping on the partner; and (3) chasing and biting the partner's hindquarters. At high intensities the initiator shook its head as it kept a neck bite on the partner, or it dragged the partner through the area by the neck. Poole described additional factorsthat inhibited play. If fear-eliciting stimuli or prey objects were present, the polecats adopted defensive threat postures and hid or chased the prey, respectively.

Agonistic behavior. Aggression appeared to take different forms, depending on whetheror not it occurred during the breeding season and which sexes were involved. Poole (1967, 1973) regarded nonbreeding season agonistic behavior as "ritual aggression," which took place whenever two polecats unfamiliar to each other were placed together. Two particular movements, "inhibited chin biting" and "dancing," were characteristic of ritual aggression. The former was composed of mutual gentle pawing and muzzle biting. If a polecat "danced," it faced its opponent and leapt off the ground, shaking its head while snapping its jaws at the partner.

When males fought during the breeding season, the interaction began with mutual anal sniffing. An attack then commenced without other threats or warnings (Poole, 1967). During the average ten- to fifteen-minute fights, "sustained biting" and "flank shielding" were observed, the latter when losers left the area. Biting composed 41 percent of the fighting interactions, and bites delivered to the neck were longest in duration (Poole, 1974). Once a fight was terminated the loser displayed an "aggressive threat" (Fig. lb) to further discourage the winner from continuing the fight. Both animals assumed a prone, outstretched position at the termination of the encounter. The winner usually "belly-crawled," moving with the forefeet propelling him forward (Fig. lc).

Use of defensive threats and sideways attacks characterized male agonistic interactions; however, they were never observed in juvenile aggressive play (Poole, 1967). In a defensive threat (Fig. la) the polecat refused to fight by arching his back, orienting his head horizontally toward the opponent, baring his teeth, hissing, and holding his neck vertically. A sideways attack was directed toward a defensive or frightened polecat during a high-intensity encounter. This movement serves to "initiate or prolong a fight with an unwilling partner. This further terrorizes the opponent who adopts an attitude which has been called defensive threat. . ." (Poole, 1966:30). The sideways attack, which occurred only after the outcome of the fight was decided, was always displayed by the winner, which probably remained in a highly aroused aggressive state. All threats, whether defensive or aggressive, were observed only after the aggressive interaction had begun (Poole, 1967).

Fig. 1. Defensive threat (a) and aggressive threat (b) in the polecat, (c) Prostration in the polecat. The hind legs are splayed outward and the feet are directed laterally. (From Poole, 1967.)

Estrous females were not so aggressive as males, although their agonistic behavior level did increase from the non-estrous state. The usual female-female interaction was characterized by ritual aggression and low-intensity fights in which one of the polecats ignored the partner's inhibited chin bites (Poole, 1967). If one of the females was pregnant, the nonpregnant female clucked and danced around the pregnant polecat, which reciprocated with a "lunge-hiss." A nonpregnant female displayed an arched back trot in reaction to the pregnant female's defense of an area. This motion consisted of short, quick steps around the pregnant female, possibly followed by the nonpregnant female's biting of her own tail.

During aggressive activities by either sex the angle of the neck was an important signaling device (Poole, 1967). Through film analysis Poole discovered that the neck was never attacked if, from the aggressor's vantage point, it appeared convex. When the neck assumed a concave or linear appearance, an attack was likely to occur. Poole further described two displacement activities that were linked with aggressive behavior. Chasing one's own tail occurred if a polecat's attack attempts were rebuffed. A polecat "scrabbled," or performed digging movements on the floor, if it had been in an attack-avoidance conflict situation.

Other behaviors. Aspects of aggressive behavior also were seen in polecat mating attempts (Poole, 1967). Anal sniffing and neck nuzzling were included in preliminary mating movements if the female was in estrous. If she was unreceptive, she delivered inhibited chin bites and necknips to discourage the male's mounting attempts. If those movements failed, she employed aggressive threats and lunge-hisses.

Finally, Goethe (1940) reported a captive female's attempt to "teach" her young to approach food objects by dragging food into the nest and then pulling it out of the nest, while still in full view of the young.

Weasels

While play has been reported for juvenile captive common weasels (Mustela nivalis) and the closely related (if not conspecific, Ewer, 1973) least weasels (Mustela rixosa), descriptions of play have not been made. East and Lockie (1964) noted that infant common weasels played together only in the nest; after fourteen weeks they were no longer tolerant of one another. Hartman (1964) observed interspecific aggression when a male common weasel shook a male ferret (Mustela furo) by its nose. Threat behavior and associated vocalizations were observed in young common weasels when they were nine to ten weeks old (East and Lockie, 1964). As the weasels matured, the threats were applied in varying contexts, including aggressive play. The female weasel initiated mating behavior by leaping around the male, which then mounted her (Ewer, 1968). The pair then alternated between bouts of play-fighting and sexual behavior for several hours. Ambiguous observations were recorded for the stoat (Mustela erminea). Some female stoats carried their young by the mane at the base of the neck, while others carried their young by the middle of the back (Ewer, 1973).

Instances of conspecific tail biting were observed in American mink (Mustela vison) when sexually excited males tried to bite unreceptive females at the base of their tails (Poole, 1967). Enders further described movements typical of courtship in the mink:

Copulation in the mink is often furious. It may be preceded by a "courtship" of varying length which resembles a rough and tumble fight. . . After a longer or shorter struggle the male secures a firm hold on the skin of the neck immediately back of the head. If after being caught the female is reluctant to breed, she arches her back. [1952:721]

The ontogenetic development of stages of defensive behavior has been described by Ternovskaya (1974).

Sable (Martes zibellina)

Individual sable differ in their aggressiveness toward humans, and in females there is a correlation of this hereditary component with fertility (Belyaev and Ternovskaya, 1973). Stages in the ontogeny of aggressiveness have been described by Ternovskaya (1974).

Marten (Martes americana)

Nonserious fighting during the breeding season was initiated by the female, and the male responded with inhibited biting (Ewer, 1968). Ewer speculated that agonistic behavior sexually stimulated the male. Teeth baring, chasing, and growling were the primary components of conspecific aggression, as noted by Herman and Fuller (1974). Much of the aggression they observed occurred near food.

Tayra (Tayra barbara)

Kaufmann and Kaufmann (1965) noted instances of unsolicited female-male grooming, in which the pair was situated head to head as she licked his ears and scratched his head with her forepaws. The male did not reciprocate nor did either tayra ever invite grooming from humans.

Grison (Grison vittatus)

In conspecific play captive grisons shook their partners by the scruff of the neck (Dalquest and Roberts, 1951). One grison exhibited similar behavior with old socks (Kaufmann and Kaufmann, 1965). The Kaufmanns also reported, however, that another pair of their captive grisons never interacted aggressively. On the other hand, Dalquest and Roberts described a posturing that occurred during grison fights in which the submissive animal flattened its entire body flush to the ground. When scolding their grisons for attacking humans, the Kaufmanns also observed this submissive posture. Dalquest and Roberts further noticed that during male-female "arguments," the female arched the posterior portion of her body and raised the tail.

African Weasel (Poecilogale albinucha)

Three types of play were observed in Alexander and Ewer's (1959) African weasels. The animals dug and burrowed in tanks of dirt for periods of up to thirty minutes. Additionally, they "romped" with one another and played with humans. During the breeding season the male bit the female at the nape of the neck and then tried to mount her. At his mounting attempts she rolled over.

Ansell (1960) observed that the African weasel's alarm reaction was to fluff the tail hair. If the weasel discovered an "interesting scent," the tail was carried vertically.

Ratel (Mellivora capensis)

A captive ratel's behavior fell into two categories, a "relaxed" state and a "fury mood" (Sikes, 1964). When relaxed, the ratel was affectionate, playful, and responsive to human voices. As the ratel played with objects, it shook them from side to side with its jaws. In the fury mood "all recognition seems to be forgotten, as the state of blind aggressiveness and ferocity mounts" (1964:32).

Badger (Meies meles)

A captive badger extended play invitations to humans by approaching them with a stiff-legged walk, "barking" all the while. He stopped short in front of a human, shook his head from side to side, and ran away (Eibl-Eibesfeldt, 1950). This badger also was reported to somersault occasionally.

Skunks

The spotted skunk (Spilogale putorius) gave a threat-bluff by charging its opponent, throwing the body forward, and moving the tail off to the side to allow spraying from the anal sacs (Johnson, 1921; Gander, 1965). The skunk did not actually spray in this position; rather, as it sprayed all four feet were on the ground, the back was arched, and the tail curved over the body (Walker, 1930) (Fig. 2).

The striped skunk (Mephitis mephitis) similarly threatened although it did not perform the handstand (Ewer, 1973; Verts, 1967). As in the spotted skunk, the back was arched and the tail was raised. Additionally, the striped skunk may shuffle backward and stamp the forefeet on the ground (Verts, 1967). Ewer (1973) added that on occasion the striped skunk rocked back and forth on the fore and hind legs.

Ritualized fighting and biting were observed prior to actual mating in the striped skunk (Verts, 1967). During mating the male scratched the female's genital area with his feet. Verts suggested that this highly unusual behavior may function to stimulate the female to become more receptive and to assume a more typical lordosis posture.

VOCALIZATIONS

Vocalizations have been determined for many of the mustelids, but the number of known calls for each species is relatively limited. Spectographic and fine-grained contextual analyses of calls have been all too rare, although call development has been studied in weasels especially. Exact descriptions of vocalizations are difficult to draw from the various studies, because of the relatively subjective names assigned tothe calls themselves.

Fig. 2. Handstand threat posture of the spotted skunk. (From Eibl-Eibesfeldt, 1957, after Bourlière.)

Weasels

Hartman (1964) made the primary contribution to the knowledge of weasel vocalizations by delineating six separate sounds made by common weasels. He heard a high-pitched squeak, which was especially "long-drawn and plaintive" in the female. East and Lockie (1964) noted that infant weasels squeaked when any movement occurred near them. The frequency of this squeaking decreased after eighteen to nineteen days of age. Neonate least weasels (Heidt et al., 1968) and ermine (Ternovskiy, 1974) also squeak.

When they were twenty-four days old, common weasels responded to squeaks with an openmouthed hiss (East and Lockie, 1964). Hartman explained the hiss as a response made partly out of fear and partly as a threat. Huff and Price (1968) concur. Ternovskiy (1974) did not note the typical hissing and "clicking" of annoyed ermine until fifty days of age. Threatening with "short sharp sounds" by adults is present in common weasels (Hartman, 1964) and this may be homologous with the clicking of ermine and the chirping of least weasels (Huff and Price, 1968; Heidt et al., 1968). Huff and Price theorized that the chirp was made when the least weasel was disturbed. Heidt's group, however, also noted chirps when juveniles initially approached live mice, when they first attempted to interact with the mice as prey objects, and when the mother threatened the youngsters, if they bothered her.

Both sexes of common weasels trilled when meeting in a friendly fashion. Both male and female least weasels also trilled prior to mating activities and females trilled when calling to the young (Heidt et al., 1968). Huffand Price (1968) suggested that the one- to two-second duration trill occurred in friendly and maternal interactions. Goethe (1950) reported another agonistic sound, an "r-r-r" vocalization, but he did not specify the context in which it was heard. When East and Lockie (1965) bred common weasels in captivity, they noticed that unreceptive females screamed when approached by the male but, if they were in estrus, they chattered to the male. At fifty-six to sixty days ermine begin to utter the "rumbling" of adults during sexual games (Ternovskiy, 1974).

"Twittering" was noted in infant common weasels (Hartman, 1964) and a perhaps homologous melodious chattering in young ermine thirty-three to forty days old, about the time the eyes first opened (Ternovskiy, 1974).

Progulske (1969) briefly mentioned two vocalizations that he heard in a captive black-footed ferret (Mustela nigripes). It chattered (in bursts of six or seven chirps) when humans approached its quarters. It also threatened humans by hissing.

If aggressive play is too rough, a polecat may squeak, cry, or yelp (Poole, 1966, 1972). While generally there is no vocalization during high intensity agonistic encounters (Poole, 1972), the animal may scream when severely frightened during a fight (Poole, 1966). A clucking sound was also heard, but never by an "intimidated" animal (Poole, 1966). Conspecific threats were accompanied by hissing and teeth baring during aggressive play (Poole, 1966).

Marten

Vocalizations known to be given by American martens occurred during the breeding season; vocalizations at other times have not been reported (Markley and Bassett, 1942; Ewer, 1973) except by Herman and Fuller (1974) in their report of growling during non-breeding season aggression. Female American martens clucked during estrus, "apparently to attract the male" (Markley and Bassett, 1942:609). Ewer (1973) further theorized that the cluck served to signal a "readiness for social contact" and physiologically to activate the male to copulate. During mating the female squealed when the male was too rough, and both sexes tended to growl or purr during copulation itself (Markley and Bassett, 1942).

Tayra

Kaufmann and Kaufmann (1965) described four distinct vocal signals and their variations in captive tayras. A high-pitched "yowl" (similar to that of male domestic cats) was heard only during preliminary mating movements. Juveniles produced low-pitched, open-mouthed "b-a-a-a" distress sounds. As the tayra matured, the frequency of the distress call decreased. If alarmed, the tayra "snorted" and jumped backward, away from the source of the alarm. Finally, three gradations of "clicking" responses were heard during aggression. Mild aggression evoked clicks lasting about three seconds, while more intense encounters produced lower-pitched, slower clicks. At the highest intensity of aggression, the tayra emitted a low-pitched, closed-mouth, teeth-baring snarl. This was the last signal preceding an actual attack.

Grison

A nasal "anh-anh" sound, seemingly a distress or separation call, was heard in captive juvenile grisons when they were separated from humans (Kaufmann and Kaufmann, 1965). The same study reported a snort of alarm in the grisons similar to that in the tayras. In agonistic interactions of low intensity, the grison produced a sound that resembled a "low motor" (Kaufmann and Kaufmann, 1965). As the intensity of the encounter increased, the vocalizations became slower, higher-pitched, louder, and barklike. If the level of aggression further increased, the grison made high-pitched barks and concurrently held the tail in an S-shaped curve. The grison screamed loudly with the mouth open and teeth bared if the fight progressed to its highest intensity. Screaming occurred immediately preceding and during attack.

African Weasel

Although Ansell (1960), Alexander and Ewer (1959), and Rowe-Rowe (1969) have noted vocalizations in the African weasel, the only call which all researchers reported in common was a characteristic half-scream, half-growl. Ansell heard this sound in response to the presentation of a freshly killed bird to the weasel, but Alexander and Ewer speculated that it might be a threat vocalization, and Rowe-Rowe interpreted it as a sound of surprise or alarm. In their 1959 study Alexander and Ewer observed that if a female emitted the scream-growl, an approaching male left her alone. Rowe-Rowe delineated three other calls in this species: a quick, high-pitched growl; a soft, self-directed grunting as the animal explored; and a low growl if disturbed. Alexander and Ewer also reported hearing a "rumbling" vocalization during male sexual behavior that may be similar to Rowe-Rowe's reported low growl of disturbance.

Ratel

A captive ratel (Sikes, 1964) was reported to give two vocalizations: a repeated "h-r-r-r—h-r-r-r" call when disturbed or when engaging in running play with humans; and a snarl, heard if the animal was teased into aggressive play with its human caretakers.

Striped Skunk

Verts's (1967) study of the striped skunk included a list of vocalizations he had observed. Perhaps because the thrust of his study was not behaviorally oriented, he did not discuss possible conspecific connotations of those sounds. However, he did show that the striped skunk "churrs," "growls," "screeches," "twitters," "coos," and "hisses." He also found that the young were more vocal than the adults. Additionally, a pregnant female hissed when disturbed, and she screeched at males that were placed in an enclosure with her. Wight (1931) observed mating calls in the striped skunk. During conspecific agonistic behavior, the striped skunk was reported to growl and spit (Cuyler, 1924).

PHEROMONES

Mustelids are distinctive among mammals in their defensive use of anal scent glands in interspecific situations. Located just within the anus, the glands are contracted by muscular action, propelling the contents toward the opponent. Although the same glands are readily available for conspecific communication purposes, they are rarely put to that use (Ewer, 1973). In addition to the anal gland, most of the mustelids also possess abdominal glands, which are dragged over surfaces or objects within a territory. The function of the abdominal gland is probably the marking of areas within a territory or home range; therefore, we may attach greater importance for conspecific communication to it. Although the anal gland may be involved in territorial pursuits, it is more likely that the abdominal gland is dominant in that role. Hall (1926) could not locate abdominal glands on the fisher, mink, or striped and spotted skunks. Developmental studies of gland morphology and secretions are rare. Specific glands and their communicative uses are discussed separately for each species.

Weasels

Ewer (1973) reported that when alarmed, various weasels (stoat, common weasel, and least weasel) emitted the contents of their anal glands. It does not appear that the abdominal glands are utilized in alarm or active defense situations; rather, as the ventral surface is dragged, the substrate is marked.

Any defense of an area by females by setting scent or otherwise cannot be a signal between adjacent territory-holding females, although scent could well act as a sign to wandering females. I suggest that female weasels and stoats defend their small territory mainly against the male owner of the territory in which they live. [Lockie, 1966:157]

After antagonistic encounters among polecats during the breeding season, the victor explored the area in which the fight took place and marked objects by sliding, rolling, and rubbing its back on the ground or the object (Poole, 1967). The loser similarly marked and rubbed the area after the victor had completed its marking. Lockie (1966) noted that polecats typically deposited urine and feces at specific spots in their territories.

Vaginal discharges of female American mink are claimed to be important to male mink in determining the female's sexual state. Volatile amines have been isolated that vary with the female's estrous cycle and hence could be the signal substances used by the male (Sokolov et al., 1974). Azbukina (1970) found several skin glands in the American mink: anal, plantar, nape, gluteal, and caudal. The anal glands are delayed in their development. This and the temporary appearance of supplemental apocrine glands (nape, gluteal, caudal) are related to the licking and massaging of pups by parents and mutual parent-pup smelling. Azbukina (1972) also described in detail the complex morphology of the anal sacs in American mink. They consist of two types of glands (apocrine and holocrine), a cavity for storing the musk, and a central excretory duct.

Marten

In captivity female American martens urinated on feces, stones, and objects within their enclosure (Markley and Bassett, 1942; Herman and Fuller, 1974). Although Seton (1929) was not dealing with captive animals, he believed that the urine marking was associated with the anal glands. Use of the abdominal glands was observed in both male and female captives, particularly as they rubbed their abdomens over branches (Markley and Bassett, 1942). The exact size of male and female abdominal glands was delineated earlier by Hall (1926), who found the female gland to be 1.0 X 6.4 cm and the male gland .8 X 4.0 cm. Both abdominal gland and urine marking increased at the onset of the breeding season (Ewer, 1973), which coincided with the increase in marking observed after the family groups had disbanded (Goethe, 1964; Herter and Ohm-Kettner, 1954).

Wolverine (Gulo gulo)

When alarmed, the wolverine normally released a particularly foul-odored anal sac secretion. Typical of most mustelids, this species marked by rubbing surfaces with the abdominal gland (Krott, 1959).

Tayra and Grison

The only reports for these species (Dalquest and Roberts, 1951; Kaufmann and Kaufmann, 1965) indicated that both used the anal gland to mark objects. This behavior first appeared in the tayra as it approached maturity (Kaufmann and Kaufmann, 1965). The yellow-green grison musk secretion was deposited after the grison raised its tail and then brushed it against the object to be marked (Kaufmann and Kaufmann, 1965).

African Weasel

In mustelid fashion the African weasel released its sweet and pungent musk from the anal glands (Alexander and Ewer, 1959; Rowe-Rowe, 1969; Ansell, 1960). Ansell argued that since the odor was not particularly foul, the species-characteristic coloration served as a warning device more than the anal secretion did. Before releasing the musk, the weasel raised the tail to a vertical position and fluffed the tail fur. The actual range of the musk spray was from 20 to 100 cm (Alexander and Ewer, 1959). Although the species never released its musk in a conspecific interaction, on one occasion a male was attracted to a female that had just sprayed in an interspecific situation (Alexander and Ewer, 1959). Urination and defecation habits of the African weasel showed that it eliminated in specific areas of its home environment. Alexander and Ewer believed that this habit "serves to show whether the sleeping quarters are or are not occupied" (1959:316).

Ratel

The anal secretions of the ratel, copiously applied to trees and stones, may serve to stimulate courtship and to establish the animal's territory (Sikes, 1964). African hunters believed that the breeding of ratels was accomplished only if the pair hunted for and attacked a beehive together. Sikes elaborates:

Perhaps a mutual-fury reaction is the necessary primary stimulus required to trigger off the hormone sequence necessary to the attainment of successful copulation and embryo implantation. Possibly there may be other essential factors to success such as the need to allow the scent to lie in the cage undisturbed for a suitable period. . . . [1964:36]

Badger (Meies meles, Taxidea taxus)

Ewer's (1968, 1973) descriptions of pocketed abdominal glands were the only sources of information available. The invertible, pouched gland presumably played a role similar to that in other mustelids, i.e., territorial marking through "anal drag" movements.

Skunks

Both the striped and the spotted skunks' anal glands were specially modified to store the foul, musky fluid (Ewer, 1973; Verts, 1967). Blackman (1911) drew the analogy of a syringe and bulb to the anal sac mechanism in these species. As the skunks sprayed, separate streams from each of two anal sacs fused and were directed toward the opponent (Cuyler, 1924). The tail was held over the skunk's back, perhaps to avoid fouling its own body. As might be expected, the release of anal fluids was limited to defensive, interspecific situations. However, it has been noted that a spotted skunk in estrus was capable of releasing a characteristic nest scent which presumably encouraged nursing behavior in the young (Tembrock, 1968).

The most recent study on the chemical composition of the male odorous component of striped skunk musk is that it contains trans-2-butene-1-thiol, 3-methyl-1-butanethiol, and trans-2-butenyl methyl disulfide, but not the commonly cited 1-butanethiol (Andersen and Bernstein, 1975).

Procyonidae

The procyonids are typically small- to medium-sized omnivores of the forest. Many are arboreal. The main subfamily (not including the pandas) is found only in the New World, particularly Central and South America. This subfamily includes such species as the raccoons, coatis, and kinkajous. They have well-developed forepaws with separated digits which allow them to manipulate objects in a superficially primate-like fashion. The pandas, in contrast, are purely vegetarian forest animals of eastern Asia. Their forepaws are more bear or doglike. Davis (1964) and Sung, Chang-kun, and Sarich (1973) argue that the giant and lesser pandas are not closely related.

When procyonids are viewed as a family, only a very sketchy picture of their communication channels can be drawn. For example, Ewer(1973) delineated specific auditory ranges and limits only for the ringtail (Bassaricus astutus: 45 kHz), the ringtail coati (Nasua nasua: 45 kHz), and the raccoon (Procyon lotor: 35 kHz). The auditory capabilities of the other species have yet to be determined.

Ferron (1973) noted that the olfactory apparatus of the raccoon was highly developed, particularly when compared to the domestic cat and the mink. Ferron's results seemed to refute Cole's earlier observation that olfaction was not well developed for locating food items (Cole, 1912); but it does support Stuewer (1943), who noted that the raccoon was capable of locating food items buried in two inches of sand.

The tactile abilities of the procyonids have been reported only for the raccoon and the coati (Welker and Seidenstein, 1959; Welker, Johnson, and Pubols, 1964; Cole, 1912; Zollman and Winkelmann, 1962; and Ewer, 1973). The paws and nose of the raccoon have the greatest amount of somatic tissue represented in the cortex (Welker et al., 1964). The coati (Nasua narica), not so adept as the raccoon in the use of the paws, utilized the snout (and its olfactory abilities) to a greater degree (Kaufmann, 1962).

The only record of procyonid visual abilities was found in the raccoon (Dücker, 1965; Mich-els, Fisher, and Johnson, 1960; and Cole, 1912). While Cole believed that the raccoon's vision was quite good, he made no mention of color vision in that species. Using experimental techniques, both Michels et al. and Dücker could find no evidence that the raccoon did discriminate colors.

MOVEMENTS AND EXPRESSIONS

Coati (Nasua narica)

Kaufmann (1962), who performed a fairly complete study of the coati, listed six primary visual signals used in its social organization. A nose-up posture was prevalent in adult male encounters (Fig. 3a). If the head was oriented downward, the situation was clearly agonistic (Fig. 3b). Head jerking and inhibited biting were seen in juveniles as they approached adult females and solicited grooming from them. Mutual grooming (between adult males and females) probably maintained the band structure by providing frequent, socially positive interactions. Tail switching occurred when two coatis faced each other. The "tail-to" position, which was performed by both sexes as the breeding season approached, seemed to serve as an appeasement gesture in reducing overt hostility.

Although fights involving physical contact were rare, they did occur, and the expressive components included nose-up postures, squeals, charging, and jockeying for position. Gilbert (1973) described a "defiant" posture used in "warning-threat-challenge" encounters. The coati spreads and bows its forelegs, raises the tail over the back, lowers and turns the head to one side, opens the mouth, and exposes teeth. The lower the head the more intense the signal. Aggression with contact, which occurred during the breeding season, could mean harsh wounds to the animals. Inhibited fighting between the sexes also occurred during the mating season. The animals would direct their paw swats toward the head, open the mouth, and jockey the head back and forth. These inhibited fights were usually terminated mutually by nose-up postures and squeals. This kind of fighting "seems to play a significant part in their relationship" (Kaufmann, 1962:133) and "helps preserve band structure by serving as a positive outlet for latent or developing hostility" (1962:161). That band structure is strong is supported by the observation of a joint attack by coatis on a boa constrictor when one of their number was attacked (Janzen, 1970).

Finally, the coati used an upright, bipedal posture when exploring visually and olfactorily. Kaufmann mentioned in passing that this bipedal investigatory stance was also observed in raccoons, kinkajous, and olingos.

Raccoon (Procyon lotor)

A primary source of information concerning expressive behavior in the raccoon is Cole's study of captive animals (1912). Aggression, which first appeared at the age of twelve weeks, involved the laying back of the ears, a lowered head, and "humped" hindquarters. The teeth were bared as the animal growled. When introducing wild male raccoons to each other, Barash (1974) noted initial hissing and tail lashing followed by a posture involving flattened ears, an elevated tail, and raised shoulder hackles. A dominance-subordination relationship was indicated by "the subordinate lowering his chin, neck, ventral body surface, and tail to the floor, and then retreating to a far corner of the cage, giving the dominant animal free access to the enclosure" (p. 795). If no such relationship developed, an arched back, retracted lips, bared teeth, and growling were added to the aggressive display.

Cole described play of long duration in his captive raccoons (up to seventy-five minutes), self-play, and conspecific types of play. In each type of play the raccoon manipulated objects or the other animal with the forepaws. When playing with each other, animals tended to grasp with their teeth and to engage inrough-and-tumble rolling play. Cole further stated that "these animals pay almost no attention to one another. Though one raccoon is retreating from you, growling and snapping, the others are in nowise disturbed. Their indifference to each other's behavior could hardly be more marked, and this fact must be taken account of in considering the question of imitation" (1912:308).

While adult raccoons, like many carnivores, are generally solitary outside of breeding and litter rearing activities, a social organization based on individual recognition nonetheless exists, as neighboring male raccoons have initial dominance-subordination relationships not found in paired raccoons from distant locales (Barash, 1974).

Red Panda (Ailurus fulgens)

The red panda's behavior has not been well documented. Morris and Morris (1966) reported that during a captive panda-human aggressive interaction, the panda charged the human in a bipedal stance, "raised like a bear." As the panda charged, it hissed.

Giant Panda (Ailuropoda melanoleuca)

Morris and Morris (1966) documented the movements of the giant panda. It used a rolling, head-swaying, diagonal walk and trotted at higher speeds. Gallops and bipedal walks, however, have not been observed in this species. During interspecific agonistic episodes the panda swatted at the enemy with a front paw. In higher-intensity encounters the panda charged, pulled the opponent to itself with the front feet, and then bit (Morris and Morris, 1966). Only a preliminary note on play is available (Kleiman and Collins, 1972).

VOCALIZATIONS

As might be expected, vocalization among the relatively solitary procyonids is predominant during infancy and adolescence and again during breeding seasons. The sounds given in the first months of life are probably most vital in maintaining mother-infant contact and in signaling alarm or hunger states. Additionally, several authors designated certain sounds emitted by infant coatis and raccoons as nonspecific distress calls (Kaufmann, 1962; Welker and Seidenstein, 1959; and Cole, 1912). Specific vocalizations in each species were enumerated as follows.

Coati

Kaufmann (1962) listed eight distinct vocalizations given by coatis, probably the most social procyonid. While grunting was heard most often in females with their young, low-intensity grunts were made by all members of a band as they fed and traveled. In certain situations grunting served both as an alarm call and as maintenance for band contact (Kaufmann and Kaufmann, 1963; Smythe, 1970). Very young coatis chittered as they approached females, soliciting grooming. The chittering continued as they were groomed. Kaufmann hypothesized that the chitter is a generalized distress call. He based his theory on the return of band members to trapped and chittering juveniles and on the occurrence of this sound during play fights and mounting by subadults. Additionally, band members responded by grunting if a coati was lost and chittered. Juveniles were heard to whine after being attacked or while hiding in vines. Squealing occurred during agonistic encounters, accompanied by a nose-up posture unless physical contact had been made. During very serious aggression in the absence of physical contact, growls and snarls could be heard in adult males. Barks were linked to alarm or startle responses. A chop-chop vocalization was made by adult males only during the breeding season. Kaufmann believed this sound was related to a ritualization of biting, inasmuch as the chuckle occurred in the presence of other males concurrently with urine rubbing and assuming a head down, "appeasement" posture. Adult males and females emitted chuckling calls, particularly when approaching each other after brief separations. Additionally, Sunquist and Montgomery (1973) observed two coatis mating 20 m above ground and emitting short high-pitched vocalizations. In a more anecdotal vein Gilbert (1973:101-15) discusses coati vocalizations.

Raccoon

Cole (1912) and Welker and Seidenstein (1959) reported a generalized distress whine by captive young. In addition Cole noted a growl while feeding, a whimper if hungry, and barks and growls during agonistic encounters. Tevis (1947) reported a "low purr" by the mother to her young, ostensibly for maintenance of contact; a "soft snore and throaty growl" when animals recognized each other; and a "snort-growl" as an invitation to aggression. Gander (1965) noticed increased vocalization during the breeding season. Juvenile screeches and female and infant twitters were observed by Stuewer (1943), and Schneider (1973) claimed that four-week-old cubs "cry very loudly, emit twittery noises, and even growl" (p. 71).

Ringtailed Cat or Cacomistle (Bassaricus astutus)

Grinnell, Dixon, and Linsdale (1937) described only two vocalizations for this species, a "snarl" made when it was disturbed and a "normal" foxlike vocalization. Unfortunately the conditions under which the foxlike calls were made were not given.

Olingo (Bassaricyon gabbii)

Both sexes of this species have a "characteristic mating call" (Poglayen-Neuwall and Poglayen-Neuwall, 1965). No other mention of vocalizations can be found in the sparse literature.

Kinkajou (Potos flavus)

Grinnell et al. (1937) reported a short whistle vocalization when young animals were separated from one another. They also noted that when the kinkajou became excited, the pitch and volume of vocalizations changed.

Red Panda

B. H. Hodgson (in Morris and Morris, 1966) made the major contribution to the literature on this species in the mid-1800s. He noted that the red, or lesser, panda hissed and spitted if provoked and displayed a "short deep grunt like that of a young bear" (p. 14).

Giant Panda

In captivity the panda "shrieks" if threatened or surprised by humans or unidentified noises (Morris and Morris, 1966). During estrus the female "bleats" and "calls" with greater than normal intensity as she scent marks her enclosure. Chinese zoo officials (Morris and Morris, 1966) reported that the male emits barks during the breeding season as he runs through the enclosure. This vocalization has not been noticed by European and American zoo personnel, however.

PHEROMONES

Communication by chemical means in the procyonids usually takes the form of scent marking. Glandular secretions may serve several complex functions, including the more obvious marking of a route or territory boundary as well as merely making the area familiar odoriferously. Ewer (1968) underscored the value that a scent may have for the animal doing the marking. In establishing an area as familiar, the animal may be enhancing its own degree of confidence while at that location. As Ewer emphasized, an animal will less readily leave an area that contains its scent. In several cases, as a procyonid left an anal secretion, it also urinated, doubly insuring that it had left a distinct mark.

Olingo

A single report indicated that the olingo rubbed its anal sacs over tree stumps and branches. As the olingo crouched over the area to be marked, rubbing and urination were accomplished (Poglayen-Neuwall and Poglayen-Neuwall, 1965).

Kinkajou

The kinkajou compensates for a lack of anal sacs by possessing paired manidular glands and enlarged skin glands on the chest and abdomen (Poglayen-Neuwall, 1962). The same report noted the male's habit of biting these glands on the female's jaw and throat during preliminary mating procedures. The biting of these areas presumably further excited the male and he consequently mounted the female. No mention was made of theuse of the abdominal and chest glands in this species.

Fig. 3. (a) Typical high-intensity nose-up posture in the coati, (b) Typical high-intensity head-down posture. (From Kaufmann, 1962.)

Coati

The coati also lacks the typical procyonid anal sacs. Glands located along the dorsal edge of the anus appear to replace them (Ewer, 1973). During the breeding season, abdomen and hind quarter rubbing in the coati occurred, accompanied by urination (Kaufmann, 1962). Typically, the male engaged in urine rubbing, performing this act on trees 5 to 8 cm in diameter or larger. If two adult males meet during the breeding season, they urine rub and emit squeals or chop-chop vocalizations as they assume nose-up aggressive postures. Kaufmann believed that this ceremony implied an interaction of a high intensity attack drive (noses up), a slightly lower-intensity escape drive (chop-chop vocalization), and a sex drive (urine rub). Kaufmann did not notice any evidence that urine rubbing kept other males out of an area. He hypothesized that current urine odors kept male agonistic encounters low by warning subordinates of a dominant male's presence in the area. A second means of chemical communication noted in the coatis was the perineal sniff (Kaufmann, 1962). During the mating season the male was able to determine which females were in heat by sniffing near the dorsal glands surrounding the anus.

Giant Panda

In the giant panda anal glands are located on a very large naked anogenital skin area. Captive female pandas may back up to preferred areas within their enclosures and rub their anogenital areas against the object with their backs arched and their tails raised (Morris and Morris, 1966; Kleiman and Collins, 1972). Although rubbing has been noted throughout the entire year, it was especially prevalent during breeding seasons. As the panda marked the area, she also shook and tossed her head and exhibited an open-mouthed grin face (Morris and Morris, 1966).

Ursidae

There are seven species of bears, among them the largest land carnivores of the world, ranging from about 30 to 800 kilograms at maturity. They are heavily built plantigrade animals and, with the exception of the polar bear, more vegetarian than carnivorous. While they have adapted to climates from arctic to tropical, they are basically north temperate forms; only the little-studied spectacled bear of the Andes mountains gets into the southern hemisphere. Bears have never lived below the Sahara desert in Africa and that, along with their bipedal and arboreal habits, omnivorous feeding, intelligence, and strength, has led to speculation that the center of hominid and ape evolution in Africa was not unrelated to the absence of bears (Kortlandt, 1972). The ecological convergence of species such as the Mountain gorilla and the eastern North American black bear, except for social organization, is quite dramatic.

Our knowledge of methods of communication in the ursids is rather limited at present. Anecdotal information (Meyer-Holzapfel, 1947; Seton, 1929; Couturier, 1953) stressed the auditory and olfactory abilities of the bears but placed much less emphasis on vision and expressive movements. Experimental evidence for sensory capabilities has been restricted to two major research efforts. Kuckuk (1937) noted that all sensory systems of the brown bears (Ursus arctos) appeared to be well developed. He further elaborated on that species' auditory and visual abilities. Visual recognition of the experimenter was performed at a distance of 15 m, and auditory signals were responded to at a distance of 150 m. Training of simple circus tasks was accomplished for these brown bears through the use of hidden food items (Kuckuk, 1937). Olfactory investigation appeared to be the major factor in locating the hidden foods.

Bacon (1973), Burghardt (1975), and Bacon and Burghardt (in press, a, b) further explored the olfactory and visual aspects of black bear behavior, and they concluded that these two perceptual systems are closely coordinated during foraging, feeding, and rare predatory behaviors. It appears that ursid vision is far more developed than anecdotal sources would have us believe; training experiments demonstrated the ability of captive subjects to discriminate hues and patterns.

Distinct vocalizations have been reported for the bears (Meyer-Holzapfel, 1957; Garrison, 1937; Stonorov, 1972; Jonkel, 1970; Pruitt, 1974; and Wemmer, Von Ebbers, and Scow, in press). The range and use of vocalizations do not appear to differ widely from what is reported for the mustelids and procyonids.

Expressive body movements appear regularly during social interactions (Burghardt, 1975; Henry and Herrero, 1974; Egbert and Stokes, in press; Egbert and Luque, 1975; Pruitt, 1974; Jordan, in press; and Burghardt and Burghardt, 1972). Unlike the mustelids, during interspecific aggression the bears do not couple bodily movements with musky anal secretions. Use of pheromones in ursids may be limited to urine marking and body rubbing (Tschanz et al., 1970).

Although spectacular coloration patterns are not so numerous in the ursids as in the mustelids and procyonids, the sloth, sun, and spectacled bears have prominent light fur patterning. The Asiatic black bear, sloth bear, and occasionally the American black bear have white V's on their chests. The protective, social, or warning function of these lighter patches of hair can hardly be surmised at this time.

MOVEMENTS AND EXPRESSIONS

Although the expressive capabilities of the ursid family have been discussed and disputed (Krott, 1961; Krott and Krott, 1963; Ewer, 1968), the literature now is reflecting the evidence that bears do possess stereotyped behavior patterns that convey intraspecific social messages. In those species investigated, it appears that bears use body postures, facial expressions, and movements to signal social intentions. Unlike their many relatives, bears have tails that are too short to be important in communication. Meyer-Holzapfel noted that "the threatening motion of baring the teeth is common to the bear, as to other animals of prey, although it lacks the 'crescendo of hissing' characteristic to all species of cats" (1957:23, trans.), and further, that "motions and attitudes are more capable of carrying expression [than the face]" (1957:23, trans). Behavioral components of fear evidenced in bears (Meyer-Holzapfel, 1957) included a "cowering attitude," an outstretched head, "wild and restless" eyes, the hissing and gnashing of teeth, and repeated withdrawal movements. Fortunately, research focusing on the presence and types of bear expressions has increased in the past few years, further expanding the very brief behavioral outlines provided by Meyer-Holzapfel and her predecessors.

Brown Bear ( Ursus arctos)

In his investigation of grizzly bear (Ursus arctos horribilis) behavior, Hornocker (1962) determined that adult males bluffed other bears during aggressive episodes. The bears vocalized prior to the threatening bluff. Hornocker further noted a distinct dominance hierarchy within the group of free-roaming grizzlies he observed. Although the attainment of rank was not described, Hornocker did delineate the effect of that rank on conspecifics. Adult males occupying the top ranks of the hierarchy were more aggressive than their subordinates. Cautious and defensive males avoided the dominant and aggressive males, behaving agonistically only if attacked or surprised. Females' ranks were temporary and relative to the ranks held by the males.

Meyer-Holzapfel (1968) noted that dominant brown bears became aggressive if they were forced to defend a tree from other bears. In their study of free-roaming Alaskan brown bears at McNeil river falls, Egbert and Stokes (in press) found that episodes of aggression and play were linked closely to the salmon level. If the salmon were plentiful, aggression was low and play increased. Subadults, who did not occupy high ranks in the group, generally were tolerant of other bears and reserved aggression for defensive situations. Other supporting evidence for these patterns of aggression has been reported (Egbert and Luque, 1975; Stonorov, 1972; Stonorov and Stokes, 1972).

During interspecific aggression Kuckuk's (1937) captive brown bears lowered their heads and slanted their snouts and muzzles toward the human. Kuckuk also utilized plywood models and stuffed brown bears to elicit aggression and exploratory behavior. He found that the stuffed specimens elicited aggressive behavior with physical contact in the male (olfactory investigation and paw swats to the head), but the female only threatened, assumed a bipedal stance, and then ran from the dummy. Both bears sniffed the plywood model and then ignored it. Heran (1966) described a defensive posture, seen when a female spotted a male in another section of a new enclosure. That posture combined "tense" ears with an arched back and bipedal stance. The head was stretched forward and the forepaws extended from the body. Heran also observed play behavior in the male-female pair after initial exploratory behaviors were forgotten. Finally, Eibl-Eibesfeldt (1957) reported that captive brown bears exhibited at least three separate movements as they begged for food from visitors (see also Hediger, 1950).

Black Bear ( Ursus americanus)

Aspects of play, threat, and aggressive behavior have been described variously by several authors, each of whom dealt with different aspects of play or aggression. Several conclusions can be drawn.

Play. The most definitive aspect of play behavior was the absence of any vocalization as opposed to the very vocal aggressive behavior (Burghardt and Burghardt, 1972; Henry and Herrero, 1974; Pruitt, 1974 and in press). Additionally, two ear postures, crescent and partially flattened, were particularly characteristic of play, whether solitary, with conspecifics, or with humans (Henry and Herrero, 1974; Pruitt, 1974). Locomotor initiatory movements of social play included circling, chasing, sideways walks, rolling over (rare), and face-to-face approaches, all of which were related to the initial intensity of the consequent play (Pruitt, 1974; Henry and Herrero, 1974; Leyhausen, 1948).

Agonistic behavior. During aggression black bears threatened conspecifics by lunging or charging, stopping short, and swatting the ground or the other bear (Jonkel and Cowan, 1971; Jordan, in press; Pruitt, 1974). Threats to humans were quite similar, involving both the sudden lunge and the swat to the ground or an enclosure fence (Jordan, in press). In an experimentally manipulated situation and in isolated naturally occurring episodes, the animal threatened from the rear (Pruitt, 1974) (Fig. 4). Redirection and displacement of aggression were also noted in these situations (Pruitt, 1974). An extension of the upper lip was exhibited during threats and aggressive play (Jonkel and Cowan, 1971; Henry and Herrero, 1974; Burghardt and Burghardt, 1972; Pruitt, 1974). In agonistic encounters the threatening bear typically assumed a lowered and outstretched head and neck posture, coupled with the eyes oriented toward the opponent (Jonkel and Cowan, 1971; Frame, 1974; Jordan, in press; Pruitt, 1974). A bipedal stance was observed in captive bears during aggression and aggressive play by Pruitt (1974), Jordan (in press), and Leyhausen (1948); however, it was not observed by Herrero (unpubl.) in free-roaming bears (Fig. 5). Urination has reportedly occurred in conjunction with intensely fearful or agonistic encounters (Frame, 1974; Jordan, in press; Pruitt, 1974; Herrero, unpubl.). Both Herrero and Pruitt attributed the unique urination and fleeing pattern to animals placed in subordinate positions, both conspecifically and interspecifically. Jordan (in press) further described a stiff-legged, sliding walk during indirect threats, although both Pruitt and Bacon (pers. comm.) observed this behavior pattern to occur when captive animals were waking or descending a tree, even in the absence of threatening stimuli.

Fig 4. threat and accompanying lip extension in the black bear. (From Pruitt, 1974.)

Mating. Ludlow provided an excellent description of courtship and mating behaviors in the black bear, finding that they showed "little courtship behavior prior to copulation" (1974: 29). The copulation behavior that she reported was quite similar to that observed in the brown bear by Meyer-Holzapfel (1957). The predominant behavior in mating was the male's neck biting and mounting after the receptive female lifted her tail (Ludlow, 1974, and in press).

On the whole, isolated ear, head, and mouth positions were not viewed as accurate indicators of impending behavior (Egbert, pers. comm.; Pruitt, in press). Instead, various combinations of facial and body expressions served as valid signals for behavior (Henry and Herrero, 1974; Pruitt, 1974). For example, if a bear approached another bear that was displaying flattened or frontally positioned ears, the initiator discontinued its approach (Henry and Herrero). Flattened ears appearing in the midst of an agonistic encounter did not necessarily dissuade an aggressor, however (Pruitt, 1974).

Fig. 5. Bipedal stance and lip extensions during black bear play. (From Pruitt, 1974.)

Polar Bear (Thalarctos maritimns)

Expressive systems in the polar bear have not been investigated to any great extent. We do know however, that captive polar bears lie curled around their young and hold the youngsters between their arms, keeping them off the den floor (Meyer-Holzapfel, 1957). Reports of social and solitary play in polar bears have been made (Meyer-Holzapfel, 1957); Vlasak, 1950), but precise movements involved in that play have not been determined. Observations of stereotyped movements in captive polar bears are abundant (Eipper, 1928; Schloeth, 1954; Holzapfel, 1939), perhaps because of the popularity of the species in zoos. The typical stereotyped movements were figure 8s, pacing, and head swinging.

Malayan Sun Bear (Helarctos malayanus)

In his observations of a captive sow and her cub, Dathe (1970) observed that the sow maintained normal contact and carried the cub in her mouth for the first seven weeks. At seven weeks, however, she came into estrus and rejected the cub completely.

VOCALIZATIONS

Meyer-Holzapfel's 1957 monograph on the Ursidae was the earliest attempt to provide a thorough understanding of bear behavior. Unfortunately she often did not delineate the species to which a behavior applied, perhaps assuming that most bears engaged in that activity. This was also true of her report on bear vocalizations. The six vocalizations that MeyerHolzapfel (1957) reported were growling, dull purring, howling, roaring, blowing, and, in cubs, the emitting of a humming sound as they nursed. Garrison (1937) also did not specify the species involved when he recorded the clicking vocalization by a sow to tree her cubs and a "muffled" sound to get them down. Instances in which the species was identified are as follows.

Brown and Grizzly Bears

Stonorov (1972) and Stonorov and Stokes (1972) reported the presence of at least three sounds in Alaskan brown bears during agonistic encounters. They heard "chomping," a rapid opening and closing of the mouth, in high-intensity aggression; "bawling," thought to act as a threat to subordinates; and "roaring," heard during aggressive threats. Couturier (1954) observed that female brown bears uttered threatening growls toward males at the conclusion of the mating season. Vocalizations were never heard during episodes of conspecific social play in freeroaming grizzly bears (Henry and Herrero, 1974).

Black Bear

Black bear cubs characteristically "purr" (Jonkel and Cowan, 1971), "hum" (Meyer-Holzapfel, 1957), or "churckle" (Bacon, 1973; Pruitt, 1974) as they nurse from the sow. This sound also has been heard when captive cubs attempted to suckle the feet, arms, and hands of their human caretakers, or parts of siblings' bodies (Burghardt and Burghardt, 1972; Leyhausen, 1948; Meyer-Holzapfel, 1957; Pruitt, 1974; Seitz, 1952; and Vlasak: 1950). A short, openmouthed, low moan (Pruitt, 1974), characteristic of juvenile discomfort or unrest, has been termed a "bleat" (Leyhausen, 1948) and a "grunt" (Jordan, in press). Huffing (Jordan, in press; Jonkel and Cowan, 1971) was a rapid exhalation of a single breath of air and may be closely akin to the anecdotal "woof' described by trappers and woodsmen (e.g., Seton, 1929). The huffing and its in-out variation occur during aggressive threat. A "squall" (Jonkel and Cowan, 1971), heard when cubs were frightened, may be similar to the long, low, closed-mouth moan observed by Pruitt (1974). A hoarse, pulsing bellow, described by Jordan (in press) and Leyhausen (1948), occurred during threat. Both Leyhausen (1948) and Pruitt (1974) described growls emitted by their captive cubs, but this sound was heard by each author only once and only in an agonistic context. During the jaw pop (Jordan, in press; Pruitt, 1974), the snapping shut of the lips caused a popping sound. The jaw pop was heard near the end of an aggressive encounter, perhaps as a defensive threat. Just prior to aggressive physical contact black bears occasionally gurgled (Herrero, ms.; Pruitt, 1974, in press). This low rumbling may serve as a final warning of serious aggressive intentions.

Polar Bear

Chuffing vocalizations and their meanings in various contexts were discussed by Wemmer, Von Ebbers, and Scow (in press). Most frequently the chuff was made by sows to their very young cubs. As the cubs matured, the frequency of sow chuffing decreased. When a sow and her cubs were separated at the age of fifteen months, all the bears chuffed and roared. A male and two females chuffed while they were being reintroduced after an eighteen-month separation. Two thirds of the observed chuffing instances were associated with transitions between one behavioral sequence and another in the female or her cubs. The cubs reacted to maternal chuffing by establishing contact with her or by ceasing their own moaning vocalizations. The chuff call was rarely given by adults. When observed in adults, it was likely to occur in a stressful situation.

In addition to mother-cub chuffing and the cubs' moaning, polar bears also blow when threatened (Wemmer, Von Ebbers, and Scow, pers. comm.) and growl and huff when captured in traps (Jonkel, 1970).

Spectacled Bear (Tremarctos ornatus)

Wemmer, Von Ebbers, and Scow (in press) reported that the spectacled bear emitted a chuffing vocalization, particularly between mother and cubs.

Sloth Bears (Melurus ursinus)

An open-mouthed, in-out exhalation termed chuffing was also reported for this species (Wemmer, Von Ebbers, and Scow, in press).

PHEROMONES

Whether bears use pheromones is highly speculative, since the size of the typical carnivore anal sacs is greatly reduced in the ursids (Ewer, 1973) and the presence of neck or shoulder glands has been disputed (Schumacher and von Marienfried, 1930; Hediger, 1949).

Brown Bear

Trees on which bears repeatedly rub have been considered as conspecific information points (Mills, 1919; Seton, 1929), as a declaration of property "ownership" (von Uexküll, 1934), as points of sexual advertisement during the breeding season (von Jacobi, 1957), and as a grooming method and pastime (Krott, 1962). Tschanz et al. (1970) investigated this tree marking-rubbing behavior in captive brown bears and noted six forms of rubbing against trees or inanimate objects. Tree-rubbing behavior occurred more frequently in adult males than females and peaked just before the onset of the breeding season. Subadults assumed defensive, bipedal stances when they approached within one meter of a tree rubbed by an adult male. The Tschanz group manipulated the location and introduction of new trees into the enclosure and then noted the bears' behavioral reactions. They observed that

the attempt of the bears to carry over the location of the rubbing places on the trunk of the old tree to that of the new can have been induced neither by its appearance nor by the scent attached with it. Rather the spatial relationship to the rest of the characteristics of the pit must have been the determining factor. According to this, the rubbing places do not only serve as a basis for rubbing, but also as points of orientation in the inhabited area. [ 1970:61—62, trans.]

Additionally, the males were particularly attentive to those areas previously rubbed by females. It was also noted that males sniffed the urine and feces left by females more frequently than the eliminations of other males. Tschanz et al. determined that the primary functions of rubbing were to differentiate areas used by each sex and to offer general information.

Meyer-Holzapfel (1957) observed anal sniffing of the female just before copulatory activities. Meyer-Holzapfel (1968) later described rubbing and biting of trees by brown bears and noted their particular attraction to strong, resinodored objects.

Black Bear

Both free-roaming and captive male black bears have been observed to sniff the female's anal-genital region while she was in estrus (Herrero, ms.; Ludlow, 1974). Published reports of black bear reactions to conspecific urine and feces traces differed from the report by Tschanz et al. (1970) on brown bears. Herrero (ms.), Leyhausen (1948), and Bacon (pers. comm.) reported that free-roaming and captive black bears did not pay special attention to the eliminations of other bears. However, captive bears did seem to have minimally overlapping areas for defecation (Bacon, pers. comm.).

Tree rubbing has been documented for black bears (Pruitt, 1974), but evidence for the function of "bear trees" is lacking for this species. Establishment of tree preferences was observed in two captive juveniles, but these preferences were not mutually exclusive (Pruitt, 1974).

Spectacled Bear

Tschanz et al. (1970) noted that captive spectacled bears tore the bark from trees in much the same manner as did brown bears.

Conclusions

The relatively solitary procyonids, ursids, and mustelids do not associate in nuclear family groups throughout the year. Instead, during the breeding season the males associate with solitary females or bands of females and juveniles. Because there is little group hunting, feeding, or living, extensive and complex social communication patterns have not evolved in these families to the same extent that they have in the more social carnivores. Yet even this conclusion should not be accepted too quickly. Vocal repertoires may, when well studied, be found to generally contain several discrete or graded calls. The coatis have the most social life style of the three families (Kaufmann, 1962; Gilbert, 1973). Tribes of females, subadults, and juveniles travel, sleep, and forage together. The males are solitary for much of the year but join the matriarchal groups for breeding and stay several months thereafter. The two cited references contrast the behavior of this fascinating procyonid in two differing environments: tropical rain forest and temperate arid mountains.

Scent marking has been a predominant means of social signalling in the mustelids and in several of the procyonids. The scent mark effectively reduces group contact by establishing home ranges or territories outside the breeding season. During estrus, scents may advertise the presence of a receptive female. The abdominal gland and urine-feces marking are the primary means for marking nests, familiar objects, and home ranges in conspecific communication. The extensive use of musky anal secretions in defensive warning and alarm situations is the most distinctive aspect of mustelid communication. The anal spray, however, serves as a warning message or even a weapon, as in skunks, that is easily interpreted and probably evolved from social usage. The procyonids have not relied so heavily upon musk emission during interspecific threat as have the mustelids. Although anal sprays and musks are not emitted by the ursids, urine and feces are available for use in intraspecific communication. Additionally, rubbing behaviors may communicate sexual and territorial information.

Coloration of a species may also function in mediating warnings or in soliciting attention. Light on dark color patterns are characteristic of the mustelids. The skunk's white stripes or spots, the African weasel's stripe, and the grison's lighter dorsal surface are all highly visible, particularly during the evening hours when the animals are most active. In the procyonids the lighter areas encircling the raccoon's eyes and the distinctive white of the giant panda may bring attention to expressive areas of these species. Light areas of fur accentuate the eyes, muzzle, and snout of several of the Ursidae, and rust-colored patches appear inside the relatively large ears of black bear cubs (Burghardt and Burghardt, 1972). These coloration patterns may further accent the facial expressions in intraspecific communication for the ursids and procyonids.

When species members do interact, the established expressive signals are probably interpreted in a situational context. For example, the procyonids do not rely on elaborate tail and facial signals. This is understandable, considering that many of the family members are arboreal, and any such signals would be often obscured from view. Data that enumerate methods of expressive communication are noticeably lacking in the mustelids. This is not to suggest that the family uses visual displays less than its carnivore relatives, but that, with few exceptions, there is little evidence of the active use of such a communication channel. Bear studies, however, have given support to the possibility of an active, if limited, use of expressive communication. Facial and body movements, as well as vocal signals, are characteristic of intraspecific communication in the brown, black, and polar bears. Behavioral data is extremely limited for all three of these families, however, and conclusive statements cannot presently be made.

Quite often the social behavior of the mustelids, procyonids, and ursids is compared to the social behavior of canids and felids without considering the vast differences in the ecologies and life histories of the various carnivore families. Because we observe a greater number of expressive signals in the canids and felids, we may conclude falsely that the mustelids, procyonids, and ursids are not capable of performing those expressive communicative acts. It must be remembered that the social organization of the group-living canids and felids probably requires a more refined communication system. The mustelids, procyonids, and ursids, however, have less need for extraneous communicative behaviors. Instead, their need is for a system that imparts precise meanings to discrete and simplified signals. Flexibility in social organization is found in these groups, however, as shown by Schneider's (1973) finding that raccoons at the northern limit of their range reverse the fall family disbanding process that occurs in more southern populations as winter approaches. The author concludes:

It may be that cubs need adult guidance to survive their first winter under the severe conditions found this far north in the species' range. In the south raccoons do not den for the winter and cubs become independent at different times within their southern range. This suggests that family behavior is as flexible and adaptive to changing conditions as their diet and habitat requirements. [1973:71]

Similar studies with other members of these three families would be most useful.

Species differences may also be approached through comparative studies, and they show that environmental effects on behavioral organization may be more pervasive than previously realized. Herrero (1972) emphasized differences in degrees of aggressive behavior in black and grizzly bears, which he attributed to ecological and evolutionary influences. The smaller, more agile black bear is able to utilize trees as protective areas, thereby decreasing the necessity for any overt defense. The grizzly bear, on the other hand, does not climb trees so easily and may need to resort to the infliction of injury when threats are not enough to defend its young. In all likelihood these behavioral traits and communication signals are, through selection, transmitted to succeeding generations (Herrero, ms.). Herrero's theory may be applied to the procyonids and mustelids as well. Environmental requirements vary widely among the species within the procyonid, mustelid, and ursid families. To be most effective a discussion of carnivore communication must include an analysis of the species' environment and its interaction with that environment. The limited accessibility and observability of many of the species in these three families has discouraged observations of their social behaviors and ecologies. Until we have more behavioral data, our understanding of these families' communication patterns will remain limited.

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