Factors influencing population growth in a bobcat population

Abstract

Bobcats (Lynx rufus) are the most broadly distributed native felid in North America and have substantial ecological and economic importance. Despite this importance, little is known about factors influencing population dynamics of this cryptic carnivore. Given recent apparent declines in abundance, we investigated population growth rate (λ) for a bobcat population in the Black Hills, South Dakota, USA, 2016–2022. We constructed and evaluated a females‐only matrix population model. Our estimate of asymptotic λ, derived from estimates of vital rates obtained over 6 years, was 0.85 (95% CI = 0.72, 1.02), which indicates that the vital rates in 2016–2022 were inadequate to sustain the population. Elasticity and sensitivity values were highest for changes in adult survival probability followed by, in order, changes in kitten and juvenile survival and adult reproductive contribution. Life‐stage simulation analysis also supported that adult survival was most important; however, the juvenile survival (91 day–1 year) component of a bobcat's first year of life was also important and a stronger influence on population growth than the kitten survival (first 90 days) component. For the combination of survival and reproductive rates we estimated positive population growth required either annual adult survival >0.85 or 275‐day juvenile survival >0.35, regardless of other vital rates. When assuming a baseline harvest rate of 23.5%, reducing the harvest rate to 9% led to a positive mean growth rate and a >0.50 probability of a growing population. Monitoring juvenile‐to‐adult harvest ratios can provide an indicator of age structure in the population, and we recommend restricting harvest when that ratio falls below 10%, particularly when managers lack research information on population growth.