Anticoagulant Rodenticides Contribute to a Decline in an Urban Carnivore

ABSTRACT Mammalian carnivores can be sensitive to human disturbance, including land‐use change leading to habitat loss and fragmentation. Anticoagulant rodenticides (ARs) have been shown to negatively affect carnivores globally and are closely tied to human activity and development; however, understanding the importance of ARs in population‐level declines is often complicated by difficulty in monitoring carnivores and the diversity of other threats they face in urban systems. We modeled contributors to annual survival in bobcats ( Lynx rufus ) over 16 years on Kiawah Island, a residentially developed barrier island off the coast of Charleston, South Carolina, USA, that has maintained a population of bobcats despite ongoing residential development. We found that across the duration of our study, the proportion of residential development within an animal's core area was not correlated with bobcat survival; however, following the initial detection of ARs in bobcats on the island, 3 bobcat mortalities (23% of all mortalities) were attributed to ARs and annual survival decreased from 0.94 to 0.39. We used our estimated annual survival rates to inform a 20‐year population projection which indicated that sustained use of ARs could lead to a local extinction within 7 years (possibly 5 years with decreased recruitment), signaling a need to reduce exposure risk of carnivores to these compounds. Based on population projections, our study presents some of the strongest evidence to date that AR exposure can contribute to population declines in carnivores.