The influence of prescribed fire on site selection in snakes in the longleaf pine ecosystem

Abstract

Prescribed fire is an essential tool for the restoration and maintenance of the longleaf pine (Pinus palustris) ecosystem. This type of management benefits wildlife species that are frequently associated with open canopy pine forests in the Southeastern U.S., including upland snakes. But few studies have examined the long term effects of prescribed fire (i.e., fire frequency over time) on snake occurrences at local and landscape scales. Likewise, comprehensive data are lacking on the response of snakes to individual prescribed burns (i.e., how long after a fire does a snake occupy a location). To investigate snake responses to these two factors, we used radio-telemetry data for five species of snakes, including three species of open-canopied forest specialists and two species that occur more broadly in upland forests (i.e., generalists), on a large site managed with prescribed fire. We hypothesized that open-canopied forest specialists, eastern diamondback rattlesnake (Crotalus adamanteus), Florida pine snake (Pituophis melanoleucus), and eastern coachwhip (Coluber flagellum) would select more frequently burned locations over less frequently burned locations and would occupy locations sooner after a fire than generalist species, eastern kingsnake (Lampropeltis getula) and gray ratsnake (Pantherophis allegheniensis). We used spatial data collected from previous snake radio-telemetry studies conducted over a nine year period (2003–2012) and annual burn data from 1994 to 2012. We used compositional analysis to evaluate snake use (selection) versus availability of locations based on fire frequency at different spatial scales (home range and landscape). As predicted, open-canopied forest specialists selected locations with more frequent fire (≤2.5 y return interval) significantly more often than locations with less frequent fire (≥3.3 y return interval; F7, 18 = 9.06, p < 0.0001). Whereas habitat generalists selected locations with fires across a broader spectrum of frequencies (every 2–10 y) significantly more often than locations that were not burned in 10 years (no burn) or those burned most frequently (1.4 y return interval; F7, 21 = 5.94, p < 0.001). The three open-canopied forest specialists, as well as the generalist, eastern kingsnake, predominantly used locations within two years after a burn (eastern diamondback rattlesnake, 81% of locations; Florida pine snake, 91% of locations; eastern coachwhip, 98% of locations; and eastern kingsnake, 91% of locations. The generalist, grayrat snake, selected locations where time since burn was less than two years (53.8% of locations), as well as, locations that had not been burned in 10 years (23.5%). Our data suggest that forest management programs that include prescribed fire with short burn return intervals (<3 y) over long time periods would benefit both open-canopied forest specialists and generalist snake species that use open-canopied forests.