Does availability of anthropogenic food enhance densities of omnivorous mammals? An example with coyotes in southern California

To evaluate whether the abundance of coyotes Canis latrans was influenced b y the availability of anthropogenic foods in a humanized landscape, we comp ared three neighboring areas thereafter referred to as NA, CA, and SA) unde r contrasting human pressures within the Santa Monica Mountains of Californ ia, USA. We quantified the use of anthropogenic foods by coyotes and assess ed local densities within these three regions. Overall, 761 coyote feces we re analyzed; identified food items were categorized into 11 food types (7 n ative and 4 anthropogenic). Though small mammals (lagomorphs and rodents) w ere the main prey of coyotes in all areas and seasons, log-linear modeling of multiway contingency tables indicates that consumption of anthropogenic foods by coyotes varied significantly throughout study areas. Thus, in the most humanized area (CA; 24% of this region is residential habitat), anthro pogenic foods (trash, livestock, domestic Fruit) comprised seasonally betwe en 14 and 25% of total items in coyote diets, whereas in the least humanize d area (NA; 2% residential) anthropogenic foods only comprised seasonally b etween 0 and 3% of items. Coyote density, estimated by foot-hold trapping s urveys and by genotyping feces, was also highly variable between areas. The heavily human-impacted CA area had the highest coyote density (2.4-3.0 ind . km(-2)), whereas coyote density was significantly lower 10.3-0.4 ind. km( -2)) in the least humanized area (NA). In the third region (SA; 10% residen tial), with an intermediate level of human pressure, both importance of ant hropogenic foods in coyote diet (4-6%) and coyote density (1.6-2.0 ind. km( -2)) were intermediate compared to the other regions. Our data suggest that subsidization by anthropogenic foods augments coyote densities and alters their diets in the Santa Monica Mountains, California. We include data from literature to show that anthropogenic foods are used by omnivorous mammals throughout the world. Surprisingly, however, the potential effects of allo chthonous inputs on such species are not well-understood. Thus. Further res earch on this phenomenon in humanized landscapes is needed.