PS 48-14 - Quantifying coyote dietary niche width in a restored grassland

Thursday, August 10, 2017
Exhibit Hall, Oregon Convention Center
Kirstie Savage, Biology, Northern Illinois University, Dekalb, IL and Holly P. Jones, Biology and Institute for the Study of the Environment, Sustainability, and Energy, Northern Illinois University, DeKalb, IL

Coyotes (Canis latrans) are one of the most prevalent predators in the United States. With the rapid decline and extirpation of apex predators, coyote abundance and geographic range have increased. Coyotes now fill the apex predator niche in many systems, but as omnivores, they differ from historical apex predators behaviorally and in diet. Thus, understanding coyotes’ dietary niche width is important to better understanding their role in community function and structure. Many studies have characterized coyote diet through traditional methods such as scat analysis. However, it is difficult to quantify the relative abundance of different prey species using such methods. Stable isotope analysis (SIA) provides a way to quantify diet that allows direct comparison between different levels of organization (i.e. individual, population), and evaluates both richness and evenness of prey items. We conducted SIA on hair samples obtained from coyotes within a 2-mile radius of Nachusa Grasslands in Franklin Grove, IL. We also collected tissue (hair, feathers, eggs, invertebrates) and vegetation samples from all the major diet constituents of coyotes. To determine the assimilated diet of coyotes and establish their dietary breadth at Nachusa, we ran a two-end member mixing model using the R package SIMMR.


Preliminary results show that dietary constituents are isotopically distinct. This is promising because isotopically distinct prey items will allow us to differentiate dietary proportions between sources. Further research in 2017 will run SIA on coyote hair to quantify the proportions of each coyote diet constituent. This will allow a better picture of how coyotes are filling the apex predator role. Predators, through top down control, are key drivers in ecological systems. Thus, understanding the interactions between predator communities and their prey is vital for ecologists, especially as apex predators are being replaced by mesopredators—as is the case for coyotes. This switch represents a shifting baseline that has the potential to cause major changes in prey species community composition and trophic interactions. By using SIA, we can quantify coyote dietary niche width, which allows us to look at this problem in a more complete manner that will increase our understanding of how coyotes shape grassland species assemblages.