Effects of Prescribed Fire on San Francisco Gartersnake Survival and Movement

The application of fire is prescribed for management of habitats for many plant and animal communities, but its effects on herpetofauna are diverse and remain poorly understood. To date no studies have examined the effects of prescribed fire on endangered San Francisco gartersnake (Thamnophis sirtalis tetrataenia) populations, despite a call for prescribed fire in the recovery plan for the species. We used multi-state capture-mark-recapture models to assess whether effects of prescribed fire were ephemeral, occurring only during the year of the fire, or persisted for 3 years following the fire, and to estimate the effects of prescribed fire on demographic parameters of San Francisco gartersnakes inhabiting California coastal prairie. Ephemeral fire effects were better supported for transitions (movement) between burned and unburned areas, but persistent fire effects were better supported for apparent survival and recapture probabilities. Movement between burned and unburned areas decreased during the year of the fire, but transition rates from burned to unburned areas decreased less than transition rates from unburned to burned areas in the year of the fire. Apparent survival probabilities increased in the unburned areas following the fire but were largely unchanged, though more uncertain, in burned areas following the fire. Recapture probabilities decreased site-wide following the fire, though the decrease was greater in burned areas than in unburned areas. Although imprecise, our estimates of the effects of prescribed fire suggest that under the conditions of this fire (low-intensity fall burn applied to a small area within a robust population and followed by wet weather), prescribed fire is a viable management tool for maintaining open habitats where San Francisco gartersnakes occur.