SEASONAL ABUNDANCE AND ACTIVITY OF A RATTLESNAKE (SISTRURUS-MILIARIUS-BARBOURI) IN CENTRAL FLORIDA

We censused a dense population of Sistrurus miliarius barbouri in cent ral Florida for three years. In 353 visual censuses of an isolated are a of semideciduous forest, we recorded 5389 sightings of pigmy rattles nakes (initial captures and recaptures). Warm winter temperatures allo wed individual snakes to remain active throughout the year. We found h igh between-census variability in the abundance of pigmy rattlesnakes (individuals seen per observer hour) during all seasons. Highest level s of abundance were associated with periodic flooding of the habitat. Individuals were found above ground at air temperatures ranging from 1 4-32 C. The cloacal temperature of captured individuals ranged from 15 -37 C. The microsites used by pigmy rattlesnakes averaged 0.4 C above surrounding surface temperatures, whereas snake cloacal temperatures a veraged 1.9 C above ambient air temperatures. Although pigmy rattlesna kes typically were passive when approached, individuals with higher bo dy temperatures and those that were uncoiled were more likely to strik e than cooler or coiled snakes. The proportion of young-of-the-year S. m. barbouri in the surface-active population was greatest during the winter and in Aug, when parturition occurs. The sex ratio of above-gro und snakes did not vary significantly among months and did not differ significantly from a 1:1 ratio. Ecdysis occurred in all months, with n o significant differences between months in proportion of snakes pre-e cdysis. Prey capture also occurred in all months of the year but was l owest in the winter. Most snakes were coiled when found; the proportio n of snakes that were moving when encountered varied significantly amo ng seasons, with peaks of movement in spring and fall. Seasonal change s in surface use and activity of this population of snakes were far le ss influenced by thermal constraints than those of snake species found in more temperate areas.