A comparison of coyote ecology after 25 years: 1978 versus 2003

Most ecological studies of coyotes are of short duration and studies are generally never repeated, thus the opportunity to compare changes in coyote (Canis latrans Say, 1823) ecology over time is rare. We compared coyote home ranges, activity patterns, age, and diet at the Welder Wildlife Refuge in south Texas between 1978-1979 and 2003-2004 (25 years later). The Minta index of overlap between 1978 and 2003 home ranges was 51.7 ± 7.0 (n = 7), much greater than the Minta index value based on randomized tests (28.7 ± 8.6), indicating similar spatial patterns between time periods. The Minta index was 12.3 ± 6.2 (n = 7) for core areas, whereas the Minta index value based on randomized tests was 4.0 ± 3.0. Although overall diets were similar between 1978 and 2003, we detected some differences in prey species consumed. Activity patterns were similar between the two study periods, with peaks in movement occurring around sunrise and sunset. There was no difference in the mean age between the two populations (P = 0.44, n = 68, t [66] = 2.00). Our findings suggest that population features, such as home-range position and age structure, are similar between extended time periods, while individual-level patterns, such as the prey species consumed and distribution of locations within a home range, are dynamic and may reflect changes in the local environment

A comparison of coyote ecology after 25 years: 1978 versus 2003

Most ecological studies of coyotes are of short duration and studies are generally never repeated, thus the opportunity to compare changes in coyote (Canis latrans Say, 1823) ecology over time is rare. We compared coyote home ranges, activity patterns, age, and diet at the Welder Wildlife Refuge in south Texas between 1978-1979 and 2003-2004 (25 years later). The Minta index of overlap between 1978 and 2003 home ranges was 51.7 ± 7.0 (n = 7), much greater than the Minta index value based on randomized tests (28.7 ± 8.6), indicating similar spatial patterns between time periods. The Minta index was 12.3 ± 6.2 (n = 7) for core areas, whereas the Minta index value based on randomized tests was 4.0 ± 3.0. Although overall diets were similar between 1978 and 2003, we detected some differences in prey species consumed. Activity patterns were similar between the two study periods, with peaks in movement occurring around sunrise and sunset. There was no difference in the mean age between the two populations (P = 0.44, n = 68, t [66] = 2.00). Our findings suggest that population features, such as home-range position and age structure, are similar between extended time periods, while individual-level patterns, such as the prey species consumed and distribution of locations within a home range, are dynamic and may reflect changes in the local environment

IMPORTANCE OF BACTERIAL DECOMPOSITION AND CARRION SUBSTRATE TO FORAGING BROWN TREESNAKES

Brown treesnakes are an invasive species to the island of Guam that have caused extensive ecological and economic damage. Efforts to control the snake population have included trapping using live mouse lures, but for logistical and economic reasons a synthetic lure is needed. When searching for live food, brown treesnakes use both visual and odor cues. However, when searching for carrion, odor cues are sufficient. Attempts to develop synthetic lures based on chemical reconstruction of the complex carrion odor have not succeeded. We provide evidence that a microbial–substrate interaction is important for bait take by brown treesnakes. Microbial cultures taken from mouse carrion indicate that Enterobacter agglomerans is the predominant bacterium, and field tests suggest that this organism may be important to odor production that attracts brown treesnakes. This information may prove useful in the development of microbial-based biological reactors that could be formulated to produce a continuous stream of odor of sufficient complexity so as to be attractive to foraging snakes

Chemical Repellents and Other Aversive Strategies in Predation Management

Chemical repellents and other aversive strategies are the core of non-lethal wildlife management. These strategies typically depend on irritation (pain), conditioning, or fear for their effectiveness, and none is universally successful. Thus, conditioned food aversions deter browsing and foraging by deer (virginianus , O. hemionus), but are less useful with predators, because killing, not consumption, is the behavior of interest. Broadly speaking, the utility of non-lethal strategies is affected by number and density of wildlife species, availability of alternative foods, palatability and novelty of treated items, and intensity of pain, sickness, or fear used to establish avoidance. Some of the most promising areas for successful predation management are those involving a combination of strategies tailored to a specific problem. For example, behavioral-contingent auditory and visual stimuli coupled with presentations of electric shock or momentary vibration (via telemetry collars) could provide an effective and unambiguous cue for withdrawal. Non-lethal methods, however, are rarely stand-alone technologies. More often, integrated strategies, involving both lethal and non-lethal methods, are required for effective predation management

Genotyping faeces links individuals to their diet

The detection of individual variation in foraging behaviour within wild mammal populations requires large sample sizes and relies on the multifold re-sampling of individuals. However, limits for observational studies are posed by the rarity and nocturnal or otherwise elusive habits of many mammals. We propose that the detection of foraging variation within populations of mammals may be facilitated if conventional diet analysis from faeces is combined with DNA-based individual identification methods using genetic fingerprinting”” from faeces. We applied our approach to a coyote (Canis latrans) population, and showed how individuals may vary from one another in their diet profiles. Two main groups of coyotes were distinguished on the basis of their relative use of small mammals and other vertebrates”” as primary food sources, and these two groups were further subdivided on the basis of their relative use of other vertebrates”” and fruit as secondary food sources. We show that, unless a faecal sampling scheme is used that maximizes the number of different individuals included in a survey, individual foraging variation that is left unaccounted for may result in downwardly biased faecal diet diversity estimates. Our approach allows the re-sampling of individuals over time and space, and thus may be generally useful for the testing of optimal foraging theory hypotheses in mammals and also has conservation applications.Peer reviewe