Introduction
The advancement of radio-telemetry for wildlife studies has allowed researchers to study the natural history of cryptic animals at a higher resolution than ever before (Ujvari and Korsos 2000). Understanding the spatial ecology of species and the temporal, biological, and ecological factors controlling it is vital for implementing conservation strategies for many species (Greene and Campbell 1992). This type of research is especially important for temperate pitviper species, such as the Timber Rattlesnake (Crotalus horridus ), especially those that migrate long distances annually, exhibit communal denning behaviors, and inhabit areas near human activity centers. Anthropogenic activities causing habitat fragmentation and structural changes that disrupt foraging and den sites, migration routes, prey densities, and many other aspects of species’ life cycles and behaviors may be the greatest threat to pitviper populations (Andrews and Gibbons 2008, Green and Campbell 1992). The Timber Rattlesnake is especially vulnerable to these types of changes because of its long lifespan, low reproductive output, and habitat requirements (Beaupre and Douglas 2009).
The movement patterns and home range use of the Timber Rattlesnake have been extensively studied in central and northern portions of its range, mostly above the 35°N latitude (Brown 1982, Brown et al. 1982, Martin 1992, Reinert and Zappalorti 1988, Reinert and Rupert 1999, Sealy 2002, Waldron et al. 2006b). In northern latitudes, populations of snakes across multiple taxa migrate away from winter hibernacula during the active season and return before the onset of the dormant season (Bauder et al. 2016). This pattern is evident in populations of Timber Rattlesnake, with males and non-gravid females generally migrating from their hibernacula in spring and traveling in a looping pattern during the active season that returns them to the same hibernacula before temperatures drop below 15 ℃ in the fall or winter (Brown et al. 1982, Reinert and Rupert 1989, Reinert and Zappalorti 1988).
Many snake species with large geographic ranges appear to exhibit more pronounced migratory behavior at higher latitudes than lower latitudes (Carfagno and Weatherhead 2008, Klug et al. 2011, Reed and Douglas 2002, Rodriguez-Robles 2003). For example, a study on home range sizes of the Grand Canyon Rattlesnake (Crotalus viridis abysus ) found that a population in Arizona had significantly smaller home range sizes than northern populations in Wyoming. The researchers attributed this difference to higher prey abundance and suitable microhabitat for hibernation and thermoregulation in the Arizona study area as compared to the patchy distribution of prey and suitable microhabitat in Wyoming (Reed and Douglas 2002). With a large distribution spanning much of the eastern, northeastern, southeastern, and central United States (Powell et al. 2016), it is possible that the Timber Rattlesnake exhibits divergent spatial ecology patterns depending on geographic location.
Determining the extent, scale, and conditions by which movement patterns and other aspects of a species’ natural history differ among populations is important because data from localized studies are often extrapolated to represent other populations (Gomez and Gregor 2015). Using extrapolated data to guide conservation and management practices can create problems if such data do not represent the population being managed. Because there are no published studies describing the spatial ecology of the Timber Rattlesnake in Louisiana, any information regarding home ranges and movement patterns must be extrapolated from populations studied in other areas. Our study compares the annual and seasonal movement patterns and home range sizes of males and non-gravid females in a population of Timber Rattlesnakes in southeastern Louisiana. Results from our study will provide insight into differences or similarities that may exist in the spatial ecology of a population at the extreme southern extent of the species’ range.