Total energy budget and prey requirements of free-ranging coyotes in the Great Basin desert of the western United States

Instituto de Ecologı́a, A.C., Centro Regional Durango, km 5 carr. Durango-Mazatlan, 34100 Durango, Dgo, Mexico
Journal of Arid Environments (Impact Factor: 1.82). 12/2003; DOI: 10.1016/S0140-1963(02)00316-6

ABSTRACT Estimates of energetic demands for carnivore species can be valuable for estimating their annual prey requirements and thus, their potential impact on prey populations. This is the case for the coyote (Canis latrans) which has a ubiquitous distribution and preys on a wide variety of wild and domestic prey species. We took data on daily activity of coyotes and with standard energy models, estimated the daily field metabolic rate (FMR) of adult male and female coyotes in the Great Basin desert of the western United States. We then calculated the total annual energy demand and from this, extrapolated annual prey needs for lagomorph and rodent-sized prey. Daily FMR of male coyotes in the Great Basin desert averaged 1170.1 kcal±29.1, S.E. (n=11) and was significantly higher than 988.6 kcal±44.3 (n=8) for females (p=0.002). The highest reproductive cost for females was lactation (1441.1 kcal/day above FMR). Males and females need to consume 192 and 162 lagomorphs, or 3681 and 3110 rodents/year, respectively. For reproduction, females should consume 37 more lagomorphs or 700 more rodents per year. We concluded that preference for lagomorphs by coyotes reflects the most reasonable energy return on their hunting investment.

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    ABSTRACT: Canada geese (Branta canadensis) have become common in many urban areas, often creating nuisance problems for human residents. The presence of urban geese has raised concerns about the spread of disease, increased erosion, excessive noise, eutrophication of waterways, and general nuisance problems. Goose populations have grown due to an increase in urbanization resulting in an abundance of high quality food (urban grass) and suitable nesting sites, as well as a decrease in some predators. I monitored nest predation in the Chicago suburbs during the 2004 and 2005 nesting seasons using 3 nest monitoring techniques to identify predators: video cameras, plasticine eggs, and sign from nest using a classification tree analysis. Of 58 nests monitored in 2004 and 286 in 2005, only raccoons (Procyon lotor) and coyotes (Canis latrans) were identified as nest predators. Raccoons were responsible for 22-25% of depredated nests, but were rarely capable of depredating nests that were actively defended by a goose. Coyotes were responsible for 75-78% of all Canada goose nest depredation and were documented killing one adult goose and feeding on several others. The coyote is a top-level predator that had increased in many metropolitan areas in recent years. To determine if coyotes were actively hunting geese or eggs during the nesting season, I analyzed coyote habitat selection between nesting and pre-nesting or post-nesting seasons. Coyote home ranges (95% Minimum Convex Polygon) were calculated for 19 coyotes to examine third order habitat selection related to goose nest abundance. A 100 m buffer (buffer habitat) was created and centered on each waterway edge and contained 90% of all nests. Coyotes showed selection for habitats during all seasons. Buffer habitat was the top ranked habitat in both pre-nesting and nesting seasons, but dropped to third ranked in post-nesting season. Habitat selection across seasons was compared using a repeated measures MANOVA. Habitat selection between pre-nesting and nesting seasons (P=0.72) were similar, while between post-nesting and nesting seasons there was a nearly significant difference (P=0.07). The insignificant change in habitat use across seasons suggests that coyotes did not switch habitat use to take advantage of goose nests. Alternatively, the change in ranking of buffer habitat across seasons suggests that coyotes may have switched habitat use to take advantage of goose nests. The results are not clear as large individual variation between coyotes due to differences in habitat availability, and social status interfere with the results of the analysis. Even though I failed to find strong support for coyotes actively hunting goose nests, they nevertheless were the primary nest predator in the area and may influence Canada goose populations. To determine the potential influence of coyotes on the Canada goose population, I created a Canada goose matrix population model that included variables such as coyote predation on adults and nests as well as coyote influence on nest desertion. Using the base population model I calculated the Canada goose population to be increasing with = 1.055. The removal of all coyote influence on the goose population would allow to increase to 1.214. Nest predation was the most important factor related to coyotes: the removal of coyote nest predation from the model resulted in a population growth rate = 1.157. Modeling results suggest coyotes are serving as a limiting factor for the Canada goose population within the Chicago metropolitan area.
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    ABSTRACT: Under predation risk, prey species are more abundant in areas of low predation risk even at the expense of forage quality. As a result two predictions are possible, 1) predators should choose to hunt in areas with fewer but easier to catch prey than areas where they are more abundant but harder to catch; and 2) the frequency of prey species in the diet of predators using low risk areas should be greater than, or at least equal to, the diet of predators using high risk areas. To test these two predictions, we used data on coyote Canis latrans abundance and diet composition from two habitats in the Chihuahuan Desert of Mexico that have different abundances of jackrabbits (Lepus californicus) and rodents. We used the number of coyote scats found in transects in the two areas to assess coyote abundance and analyzed the contents of these scats to determine diet composition. We found significantly more coyote scats/yr (22.6 ± 4.7 (SE) vs. 12.2 ± 2.4 scats/yr, d.f. = 7, paired t = 3.80, P = 0.007) in the habitat with less jackrabbits and more rodents. However, the percent occurrence of jackrabbits (54.3 ± 6.7% vs. 60.1 ± 7.7%) and rodents (32.6 ± 6.5% vs. 30.1 ± 6.0%) in coyote scats did not differ between the two habitats. These results supported both the above cited predictions and the hypothesis that prey vulnerability can influence habitat use by coyotes. Optimal foraging predicts that an animal should forage where it is most profitable and where it incurs the least costs in obtaining food resources (Sih 1980, Pyke 1984). Based on this theory, animals should forage where food is most abundant or of highest quality (Sih 1980, 1984). However, for prey species, predation risk is an important foraging cost (Brown 1988) and animals will consider it in their foraging decisions (Altendorf et al. 2001, Hernández and Laundré 2005, Brown and Kotler 2004). Habitat characteristics, e.g. frequency, availability, and location of cover, can influence the level of predation risk by mediating the lethality of the predator and thus the vulnerability or catchability of the prey (Messier and Barrette 1985, Brown and Kotler 2004, Laundré and Hernández 2003a). Consequently, predation risk will vary over a landscape mosaic of habitat characteristics, i.e. the landscape of fear (Messier and Barrette 1985, Laundré et al. 2001, Laundré and Hernández 2003a). Within this landscape, prey must balance forage resources available with their vulnerability to predation within each habitat. The result is a deviance from what is predicted under classic optimal foraging with prey often being more abundant in areas of lower risk even if they provide fewer foraging opportunities (Edwards 1983, Sih 1984, Wolff and Van Horn 2003, Hernández and Laundré 2005, Creel et al. 2005).
    The Open Ecology Journal 01/2009; 2:1-6.


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