Hunter J Cole; Institute for Wildlife Studies; hcole@iws.org; David K. Garcelon, Andrew S. Bridges, Grantham R. Lewis, Grantham R Lewis

Native and invasive predators are responsible for billions of dollars in damages annually – a problem often mitigated through lethal removal. Quantifying removal effort effectiveness is critical for sound wildlife management. Here, we demonstrate the use of statistical population reconstruction (SPR) for modeling population trends in lethally-removed mammals. This technique requires minimal resource expenditure beyond routine removal efforts. SPR can be used to reconstruct total population size as well as age demographic structure for lethally-removed mammals for all removal periods for which age-at-harvest data is available. We used SPR to reconstruct a population of feral cats removed from San Clemente Island, California, as part of ongoing endangered passerine recovery efforts. From 2009–2020, 1,952 cats were removed and subsequently aged using cementum annuli analysis. Using age-at-harvest data and a single abundance estimate within an SPR analytical framework, we obtained annual cat population size, age-class structure and harvest probability by age class. The population estimates obtained from this analysis can be used as a parameter in subsequent analyses to monitor removal program efficacy and assess the impact of invasive predator density on native fauna, providing the ability to assess novel removal technique efficacy and prioritize predator removal among other conservation actions.

Carnivores - Canids and Felids  InPerson Presentation