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

Abstract

Domestic cats (Felis catus) are one of the world’s 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 (ψnaïve = 0.45) and 41 randomly distributed monitoring points (ψnaïve = 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 (ψmean = 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.HighlightsWe surveyed for domestic cats across 55 suburban preserves from 2010-2018.We modeled occupancy and detectability as a function of urban covariates.Cat occupancy was low overall and best predicted by building density.The risk to native species is highest near preserve boundaries bordered by built environments.

Counting the Capital's cats: Estimating drivers of abundance of free‐roaming cats with a novel hierarchical model

“…Our results are compelling and provide evidence of different environmental and socio‐economic drivers of cat distributions across the gamut of habitats that the urban environment offers. Cats were mostly associated with residential areas and were largely absent from large, protected areas such as Rock Creek Park and the C&O Canal National Historical Park, with relatively few detections in the other public spaces such as the National Mall, district parks, and the National Arboretum, corresponding with previous research from the Chicago metropolitan area (Vanek et al, 2021). These associations are noteworthy because they suggest that cats may be relatively rare in protected spaces even in the vast expanses of an urban environment such as D.C. and therefore precludes the strong possibility of significant impacts from free‐roaming cats in those protected areas.…”

“…Here, we present results from the D.C. Cat Count, a collaborative project among conservation and animal welfare groups established to estimate how many free‐roaming cats exist in the U.S. Capital (Flockhart et al, 2022). We hypothesized that cats would be strongly associated with humans in the urban environment and this effect would be exacerbated by socioeconomic factors (Cove et al, 2019; Vanek et al, 2021). Therefore, we predicted that cat density would be heterogeneous across the district such that free‐roaming cat abundance would be highest in areas with less green space and lower median income.…”