The niche variation hypothesis posits that intrapopulation niche differentiation arises because generalist populations include relatively specialized individuals that use different resources. Diet variation among individuals is expected to increase with spatial variation in resource availability.

Cities are very heterogeneous & food availability varies across neighborhoods. So, does urbanization create conditions favorable for individual specialization? We tested this hypothesis by comparing the diets of an urban pop of #coyotes in #SanFrancisco to a nonurban pop in Marin County.

Coyote whiskers grow gradually over several months, so we cut each whisker into small segments. Each segment gave us a isotopic “snapshot” of diet from a different point in time, letting us measure how consistent (or variable) an individual’s diet was ✂️🐾

We found that individual urban coyotes had dietary niches almost 3x narrower than nonurban coyotes. Similarly, urban individuals had more consistent diets (smaller residual intraindividual variabilities). That means each urban coyote was consuming a smaller “menu” of food types.

Within-individual differences in ratios of both isotopes contributed far less to total niche variation in the urban than the nonurban coyote population, providing strong evidence for greater individual diet specialization in the urban population 🌇👤🍽️

Taken together, while each urban individual eats a narrow diet, individuals in the city eat quite different diets from one another, especially with regard to human food consumption. But like our scat study, individuals living in the same territories had relatively similar diets 🍗