Annual and daily activity cycles of snakes in northern Virginia, USA

T annual and daily activity cycles of North American reptiles are determined by physiological responses to both temperature and light; and are seasonal (Gibbons & Semlitsch, 2001). While many field studies of North American snakes have included data on seasonal activity patterns, their daily activity cycles have been mostly under reported in only general terms. This is the only long term study of a snake in the middle Atlantic region of the USA, and as such is valuable for comparison with other such North American research; and reports baseline information which may also be critical to future studies on the effects of global warming on snake communities. Ecology of 16 snakes (Table 1) was studied at the Mason Neck National Wildlife Refuge, Fairfax County, Virginia, USA (38° 67' N, 77° 10' W, ~2535 m elevation), from April 1982 to August 2006, but concentrated from 1990 to 2006 (Hartsell, 1993; Ernst et al., 1997; Creque, 2001; Orr, 2003, 2006). Calculations of the annual and daily activity cycles are reported below.