The influence of predators on the survival and abundance of isolated neighboring populations of the Florida scrub lizard (Sceloporus woodi)

Predators and their prey often experience the landscape at different spatial scales. For example, a wide-ranging predator may prey upon habitat specialists with much smaller distributions. As part of an investigation of predator-prey interactions in Florida scrub habitat, we examined the diet and movements of the widely-foraging coachwhip (Masticophis flagellum), and its predatory effects on the survival and abundance of the narrowly-distributed Florida scrub lizard (Sceloporus woodi). We used the robust design in a mark-recapture study, and modeled the influence of weather, patch characteristics, individual covariates, and abundance of snake predators on survival and abundance of the lizard prey. Huggins' closed models indicated that capture probabilities within months varied as a function of time, weather, and/or lizard size, depending upon the season. Temperature was an important determinant of capture probability during cooler periods, and size was an important determinant concurrent with the presence of hatchlings and juveniles. Closed models also showed that Florida scrub lizard abundance varied substantially over time and between patches of scrub, with peak abundances generally occurring in early-mid summer. Preliminary investigations using Cormack-Jolly-Seber open models indicated constant survival rates, but models with patch effects also received some support. Open models also indicated that capture probabilities varied among months, being greatest during the peak of breeding activity in spring. Although no strong effects of predators were detected, small and/or infrequent influences of predators can promote regulation of their prey. In this system, auxiliary data indicates that the coachwhip tracks the abundance of its Florida scrub lizard prey.