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.