The Distribution and Abundance of Coyotes: The Effects of Allochthonous Food Subsidies from the Sea

Abstract

We analyzed how the distribution and abundance of a major consumer, the coyote (Canis latrans) is influenced by the input of food from the sea. In the arid deserts of Baja California, coyote abundance along the shore of the Gulf of California is much higher compared to adjacent inland areas. These high densities are achieved because coastal coyotes are subsidized by the flow of abundant and diverse resources that come directly and indirectly from the ocean. Analysis of scats between coastal and inland sites indicates that the diet breadth of coastal coyotes is expanded (i.e., more food types were eaten) and that much more food is consumed by individuals and populations of coyotes in coastal regions. On average, scat mass at coastal sites is more than double that at inland sites. An average of 47.8% of all items found in coastal scats come directly from the sea. Such allochthonous input facilitates a numerical response: each of our four measures of coyote abundance shows that coyotes are significantly more dense along the coast than inland. Coyote populations on the coast are 2.4–13.7 times more dense than in adjacent inland areas that do not receive marine input. We present data from the literature to suggest that the use of marine resources by carnivorous mammals is widespread worldwide.