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

Abstract

Free-ranging domestic cats (Felis catus) 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 been well studied in some locations, relatively little is known about cats inhabiting suburban 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 to 2018 (4440 trap days), we recorded 355 photos of free-ranging cats at 41 randomly distributed monitoring points (ψ naive = 0.18) within 26 preserves (ψ naive = 0.45). Cats were detected every year, but rarely at the same point or preserve, and cats were active during day and night. Cat occupancy increased with building density and detectability was highest near preserve boundaries. Based on our top-ranked model, predicted occupancy within individual preserves ranged from 0.07 to 0.42 (ψ mean = 0.12) depending on the year. 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 feral cats). We discuss the conservation and management implications for suburban natural areas.