Anthropogenic factors influence the occupancy of an invasive carnivore in a suburban preserve system

Abstract

Domestic cats (Felis catus) are one of the worlds most damaging invasive species. Free-ranging cats kill billions of wild animals every year, spread parasites and diseases to both wildlife and humans, and are responsible for the extinction or extirpation of at least 63 species. While the ecology and conservation implications of free-ranging cats have well studied in some locations, relatively little is known about cats inhabiting urban nature preserves in the United States. To address this knowledge gap, we used camera traps to study the occupancy and activity patterns of free-ranging cats in 55 suburban nature preserves in the Chicago, IL metropolitan area. From 2010-2018 (4,440 trap days), we recorded 355 photos of free-ranging cats across 26 preserves ({psi}naive = 0.45) and 41 randomly distributed monitoring points ({psi}naive = 0.18). Cats were detected every year, but rarely at the same point or preserve, and cats were largely crepuscular/diurnal. Using single-season occupancy models and a "stacked" design, we found that cat occupancy increased with building density and detectability was highest near the urban/preserve boundary. Based on our top-ranked model, predicted occupancy within individual preserves ranged from 0.09 to 0.28 ({psi}mean = 0.11) and was poorly correlated with preserve size or shape. Overall, our results suggest that free-ranging cats are rare within suburban preserves in our study area, and that these cats are most likely owned or heavily subsidized by people (which pose different risks and management challenges than truly feral cats). We discuss the conservation and management implications for urban natural areas. HighlightsO_LIWe surveyed for domestic cats across 55 suburban preserves from 2010-2018. C_LIO_LIWe modeled occupancy and detectability as a function of urban covariates. C_LIO_LICat occupancy was low overall and best predicted by building density. C_LIO_LIThe risk to native species is highest near preserve boundaries bordered by built environments. C_LI