Effects of body size and sex of Drymarchon couperi (eastern indigo snake) on habitat use, movements, and home range size in Georgia

Abstract

The federally threatened eastern indigo snake (Drymarchon couperi), native to the southeastern Coastal Plain of the United States, has experienced population declines caused primarily by habitat loss, degradation, and fragmentation. To examine spatial and habitat use requirements of the species, we radiotracked 32 eastern indigo snakes from 2002 to 2004 on Fort Stewart Military Installation and adjacent private lands in Georgia. We estimated annual and seasonal home ranges and evaluated a priori hypotheses examining morphometric and ecological factors (sex, body size, location) associated with intraspecific differences in home range size. We analyzed habitat use hierarchically by examining use across the study area and within home ranges. Annual home range size varied from 33 ha to 1,528 ha (average minimum convex polygon: truex¯2003=378 ha; truex¯2004=340 ha). Individual home range size was most influenced by sex (males with larger home ranges) followed by body size. Compositional analysis of habitat use suggested positive selection for wetland, evergreen forest, and pine‐hardwood (mixed) forest, with an avoidance of roads and deciduous forests. Seasonally, indigo snakes used the highest diversity of habitats as they moved from xeric uplands (sandhills) in winter and early spring to wetlands and uplands other than sandhills in summer; however, snakes continued to use sandhill habitats (35–58% of locations seasonally) with gopher tortoise (Gopherus polyphemus) burrows throughout the warmest months. In Georgia, management and conservation of the eastern indigo snake should include conservation of large tracts of undeveloped land, containing a matrix of xeric uplands with suitable underground shelters and adjacent wetland habitats. © 2013 The Wildlife Society.

To cross or not to cross: modeling wildlife road crossings as a binary response variable with contextual predictors

“…This positive effect of snout‐vent length was consistent with observations of increased terrestrial locomotion by larger Brown Treesnakes (Rodda and Reed ) and greater movement rates and road use by larger snakes of other species (Brito and Álvares , Andrews and Gibbons , Hyslop et al. ). If road crossing avoidance results from a reluctance of snakes to depart forest cover as a form of antipredator behavior, as suggested by the gap width effect, it may be logical that such avoidance is greater in smaller snakes that may be more vulnerable to a wider variety of predators (Mushinsky and Miller , Bittner ).…”

“…, Hyslop et al. ). Increased movement activity increases the potential for contact with roads and road mortality associated with vehicle‐snake collisions, and more vagile species and life stages may be particularly vulnerable (Jochimsen et al.…”

“…, Robson and Blouin‐Demers , Hyslop et al. ). Road noise and traffic levels also have a strong deterrent effect on cross‐road movements of snakes and other wildlife (Alexander et al.…”

Optimal husbandry of hatchling Eastern Indigo Snakes (Drymarchon couperi) during a captive head-start program

“…The recovery plan for D. couperi, accepted in 1982, outlined steps for protection, recovery, and eventual removal of the species from federal protection. Part of the plan included reestablishing extirpated populations via headstarting of juvenile snakes [Hyslop, 2014].…”

Effects of supplemental hydration on physiology and behavior of Northern Pacific rattlesnakes (Crotalus oreganus oreganus)

“…The Home Range Tools extension for ArcGIS (Rodgers et. al 2007) was used to calculate 100% and 95% minimum convex polygon (MCP) home range sizes, which are frequently used for studies on rattlesnakes (Hyslop et. al, 2014;Putman et.…”