Stable carbon and nitrogen isotope analysis data for sequentially sampled whiskers of caracals (Caracal caracal) on the Cape Peninsula, South Africa

Urbanisation critically alters the availability of resources and the
nature of risks for wildlife. Despite these challenges, carnivores
frequently persist in and around urban environments, where novel
opportunities, such as anthropogenic food, may outweigh associated
ecological risks. Here, we investigate the responses of an urban adapter
to novel resources, using stable isotope analysis of vibrissae (whiskers)
to understand the spatiotemporal foraging patterns of caracals on the
fringes of the city of Cape Town, South Africa. Caracals (Caracal caracal)
are medium-sized felids and the largest remaining predators on the Cape
Peninsula. Using isotopic niche metrics and home range estimates we assess
the comparative effects of demographics, seasonality and urbanisation on
variation in individual foraging behaviour from GPS-collar monitored
caracals (n=28) across an urban gradient. Despite a wide isotopic niche at
the population level, we observed high levels of individual
specialisation. Adult and male niches were wider likely due to larger home
ranges, which facilitates exploitation of diverse prey across trophic
levels. Patterns in δ13C were seasonal, with increases during the warmer,
drier summer months across the Peninsula irrespective of habitat use.
Taken together with niche contraction for caracals in urban areas, our
findings suggest higher individual reliance on anthropogenic resources in
summer. Caracals using areas dominated by wildland cover had higher δ15N
values and larger niches than those using urban-dominated areas. Across
the study area, δ15N values varied spatially, with increased enrichment in
caracals using more coastal and wetland areas and consuming more marine
and wetland-adapted prey, particularly in winter. Individual foraging
flexibility in caracal is clearly a key strategy for their success in this
rapidly transforming landscape. Understanding spatiotemporal shifts in
dietary niche and trophic ecology in adaptable urban carnivores, like the
Cape Peninsula caracals, is fundamental for understanding the ecological
needs of wildlife in and around rapidly growing cities.