by Marc Bekoff *
The coyote is highly adaptable, exhibiting many behavioural variations under different ecological circumstances. It continues to thrive despite considerable human persecution.
[Ed. - we plan to post the figures on-line soon!]
Coyotes, Canis latrans Say, 1823, are medium-sized, sexually dimorphic, nearctic carnivores, originally inhabiting open country and grasslands. They continue both to amaze and to antagonize people because of their incredible success in resisting increased attempts by some humans to control and manage them, both by the random killing of individuals (including brutal planned community hunting) and by the use of frequently very inhumane methods that are rarely effective (Knowlton, Windberg, and Wahlgren, 1985; Scanlon, 1991; Fitzgerald, 1993).
Coyotes can adapt to diverse habitats and show considerable variations in social behaviour and social organization which are closely related to food resources (for discussion, see the following representative references from which this brief summary is taken: Bekoff, 1977a, 1978, 1982; Camenzind, 1978; Bowen, 1981, 1982; Messier & Barrette, 1982; Bekoff, Gittleman, & Daniels, 1984; Pyrah, 1984; Bekoff & Wells, 1986; Gese, Rongstad, & Mytton, 1988a,b; Mills & Knowlton, 1991; Thurber & Peterson, 1991; Harrison, 1992; Holzman et al., 1992; Larivière & Crête, 1993; Peterson & Thurber, 1993; Bright, 1993).
The decline of competitors such as grey wolves (C. lupus) and possibly cougars (Felis concolor; Boyd & O'Gara, 1985) was probably an important factor contributing to the range expansion and increasing success of coyotes. Overgrazing by livestock resulting in a more hospitable habitat for the small rodents on which coyotes prey might also have been influential. While coyotes are revered by many native American Indians (Bright, 1993), they also engender bitter hatred from some people who unjustly blame them for numerous ills. It is this hatred which forces us to confront many ethical issues that center on the control and management of wild predators. This topic will be covered in detail in an article in Canid News issue 4.
Highly mobile (they can reach speeds of 48km/hr) and opportunistic, coyotes currently thrive in virtually all types of habitat ranging from arid warm deserts, to wet grasslands and plains, to forests, to colder climates at high elevations (up to about 3000m), to large urban cities such as Los Angeles, California. They are now found between about 10·north (northern Alaska) and 70·south (Costa Rica) and throughout mainland United States and Canada.
Males are typically heavier (8-20kg), taller, and longer than females (7-18kg), although there is significant geographic and subspecific variation among the 19 recognized subspecies. Head-body length ranges from about 1.0-1.6m, and the tail is about 0.4m long. Hair is generally longer and coarser in northern subspecies. Coyotes at higher altitudes tend to be grey and black, whereas those in the desert are more fulvous. The belly and throat are paler than the rest of the body, and melanistic coyotes are rare.
Coyotes are usually smaller (lighter and shorter at the shoulder) than grey wolves, but overlap in size with domestic dogs, C.familiaris, and red wolves, C.rufus. The nose pad and hind foot pad are smaller than in lupus, but latrans has longer ears. Coyotes usually have a shorter stride than lupus and rufus. Latrans can be differentiated from lupus and familiaris by dental characters, but these are often unreliable. Latrans also can be differentiated from lupus by cranial measurements and brain morphology (smaller braincase, zygomatic breadth, and bite ratio, no dimple in the middle of the coronal gyrus, different gross cerebellar morphology) and from rufus (narrower skull and less pronounced sagittal crest, different gross cerebellar morphology). They can also be distinguished from lupus and familiaris using serological and behavioural measures; coyotes are typically more aggressive as infants than either of these canids. Fur is of approximately the same insulative value as that of lupus.
Coyotes are frequently portrayed as cunning tricksters, gluttons, outlaws, spoilers, and survivors in American mythology and in Native American tales. These characterizations are based mainly on this maligned predatorµs uncanny ability to survive and reproduce successfully in diverse locations and in extremely harsh conditions, even during unrelenting and abusive onslaughts by humans. It is important to emphasize the incredible adaptability and particularly the behavioural variability of coyotes; references to the way in which ·theº coyote lives can be misleading.
Studies of coyotes allow different behavioural patterns to be analyzed as phenotypic adaptations to local conditions (Bekoff & Wells, 1986). In some places coyotes live like typical grey wolves - in resident packs that are essentially closely-knit extended families consisting of overlapping generations of parents, young-of-the-year, and helpers of varying genetic relatedness. In other habitats they live either as resident mated pairs or as transient single individuals showing little or no site attachment. The mated pair seems to be the basic social unit.
The relative frequency with which different social groups are observed can vary from location to location and seems to depend mainly on the nature of food resources (Camenzind, 1978; Bowen, 1981; Bekoff & Wells, 1986; Gese, Rongstad, & Mytton, 1988a; see also Gese, Rongstad, & Mytton, 1988b). Pack members share in territorial defence and some serve as helpers for rearing young and for defending territories outside the breeding season. At least in northern climates, packs typically form when there is sufficient food in late autumn and winter to allow young-of-the-year to form strong social bonds with older pack members; this results in some young-of-the-year remaining with their parents and older siblings.
Coyotes enjoy a catholic diet including plant and animal matter (including reptiles; Hernández, Delibes & Hiraldo, 1944) and inanimate objects. Although coyotes are opportunistic predators, they can also be very selective hunters in certain situations (e.g. Hernández & Delibes, 1944). Diet varies greatly both seasonally and geographically, as do the methods by which prey are acquired. Coyotes are active predators relying primarily on vision whilst hunting, and they have been observed to fish and climb trees in pursuit of food. They are also successful scavengers. The success of hunting attempts varies with age, prey type, grass height, and snow depth.
A study by Bekoff & Wells (1986) showed that adults and juveniles were about equally successful when they hunted small rodents (about 20-25% of the time). Adults and juveniles also enjoyed their highest success rate when they hunted gophers and were least successful when they hunted voles. Coyotes were also more successful when they hunted small rodents in short grass and shallow snow. Wind conditions did not influence hunting success. This trend is consistent with the notion that vision is more important to coyotes than olfaction (or audition) when they are hunting small rodents. Grass height (c.f. snow depth, wind conditions, and prey type) accounted for the greatest amount of variation in the duration of searching and orienting.
Higher rates of hunting success on small rodents seem to be associated with greater variability of predatory sequences, suggesting that coyotes vary their behaviour according to the immediate situation in which they find themselves. Furthermore, average stalking duration during successful hunts is longer than average stalking duration during unsuccessful hunts.
For the most part, large ungulates who are actively sought by coyotes do not constitute a major portion of their diet except when alternative food is scarce or when young, old, sick, or otherwise defenceless individuals are encountered.
Coyotes are almost always monogamous and pair bonds between a male and female can last more than four years. In packs usually only one pair mates per season. Both males and females are able to breed during their first year of life, usually when they are about 9-10 months old. Females show one oestrous cycle per annum, and males also appear to go through an annual cycle of spermatogenesis. Oestrus lasts about 2-5 days and ovulation occurs about 2-3 days before the end of female receptivity. Coyotes typically breed once a year, in early-to mid-winter, depending on location. Courtship can last for as long as 2-3 months before mating takes place, and during copulation the male and female become tied to one another. The gestation period averages 63 days (58-65) and mean litter size is about six pups with an even sex ratio at birth; litter size can vary with population and prey density. Pups are born blind and helpless, usually in an excavated den. They emerge from the den at about 2-3 weeks of age, and are weaned at about 5-7 weeks of age. Mortality is typically highest during the first year, and greatest life expectancy seems to be between about 2-8 years of age. Mortality depends greatly on the level of exploitation to which populations are exposed. Coyotes can live as long as 18 years in captivity, but in the wild few live longer than 6-10 years. Coyotes can produce fertile hybrids when they mate with grey wolves, red wolves, domestic dogs, or golden jackals.
Dispersal of young-of-the-year from their natal area usually occurs between 4-10 months of age; although some individuals disperse after they are one year old. Only rarely will an entire litter remain intact for longer than a year. There does not appear to be any sex differences in the proportion of individuals which disperse or in the time period or distance individuals travel before they settle down (if they do settle down). Dispersal by young animals is highly risky; dispersing individuals generally suffer much higher mortality than do their sedentary peers who remain in their natal group in the area in which they were born (Bekoff & Wells, 1986; Harrison, 1992).
Causes of dispersal are unknown, although there appears to be an association between food availability and dispersal. When there is more than enough food for the mated pair, competition among individuals is reduced, social bonds are more likely to form among at least some group members, and the likelihood for dispersal is reduced (Bekoff, 1977b; see also Harris & White, 1992; White & Harris, 1994). It remains unclear whether or not aggression among young or between adults and young plays a role in dispersal, but available data do not support this notion (Bekoff, 1977b). Some dispersing individuals continue to live as transients, whereas some join up with another individual(s) with whom they associate for varying periods of time. It is not known whether coyotes who disperse are more likely to breed than are more sedentary individuals.
Food supply appears to be a major factor influencing social organization and the use of space in some, but, not all studies (for review see Bekoff and Wells, 1986; see also Gese, Rongstad, & Mytton, 1988a). When packs form, defence of food and territory is shared by pack members. Bekoff & Wells (1986) found that it took an average of more than two individuals (more than just a mated pair) to deter intruders successfully. Packs are also frequently found around dead ungulates such as deer, elk, and moose, and while coyotes will kill these animals, there are few actual observations of this event; often packs merely congregate around carcasses of animals which died of other causes.
It is difficult to generalize about the size of coyote home ranges; there are no consistent sex differences. Home ranges can be as large as 50-70km², but differ regionally and seasonally (with respect to temperature, food supply, the reproductive status of the female, the presence of pups), and also vary according to the age and type of individual who is being studied (transient or more sedentary pack member). Other influential factors include mortality rate (which might be related to food supply), the presence of other coyotes and potential competitors, intensity of exploitation, and the amount of population control to which individuals are subjected (for discussion see Bekoff, 1977a, 1982; Bowen, 1982; Laundré & Keller, 1984; Bekoff & Wells, 1986; Gese, Rongstad, & Mytton, 1988b; Mills & Knowlton, 1991; Holzman, Conroy, & Pickering, 1992).
Coyotes communicate using a rich repertoire of olfactory, tactile, vocal, and visual signals; many of their social signals are common to other canids (Fox, 1971; Lehner, 1978). Coyotes (usually males) scent-mark using urine in and around territory boundaries and areas of high intrusion by non-pack members. Males also mark during courtship and mating, while travelling, and during aggressive encounters. Marking by females is generally associated with the acquisition and possession of food, with the denning season, and with the location of the den. It should be emphasized that whilst marking by coyotes may serve some territorial function (e.g. urine marks may advertise territorial boundaries), the data-base is not very strong. For example, marks do not seem to serve as barriers through which trespassers will not travel.
Although coyotes do not often groom one another they will frequently rest close to one another, and tactile contact may be important for reinforcing social bonds. Coyotes use vocalizations extensively, and may howl following a reunion, to announce their location, to announce territorial occupancy, or possibly because they ?enjoyµ doing so (Lehner, 1978). They display a wide variety of facial expressions, and by combining these expressions with different vocalizations and various gaits, postures, ear positions, and tail positions, they are able to send many subtle messages to other individuals (Fox, 1971).
While many people study coyotes and other carnivores because they respect and admire them, there are those who regard these predators as pests which should be eradicated. Thus coyotes and other carnivores often find themselves in serious confrontations with humans who claim that they do extensive damage to livestock and game. As a result of these accusations, coyote populations are subject to control and management programmes involving trapping, shooting and poisoning campaigns. Such tactics raise serious ethical questions about control and handling of animals, some of which apply not only to predator removal, but to scientific research. These issues will be discussed in an article to appear in issue 4 of Canid News.
* Marc Bekoff is in the Department of Environmental, Population, and Organismic Biology, University of Colorado. In the past he has studied the social behaviour and behavioural ecology of various canids, especially coyotes. He is also very much interested cognitive ethology and animal welfare.
© 1995 International Union for the Conservation of Nature and Natural Resources
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