Spatial Ecology and Habitat Use of the Western Massasauga (Sistrurus Tergeminus) in Nebraska

Abstract

We used radiotelemetry during 2004 and 2005 to investigate seasonal movements and habitat use and to improve our understanding of how land management practices were affecting Western Massasauga (Sistrurus tergeminus) populations in Nebraska. We found Western Massasaugas to brumate in crayfish burrows 100% of the time, and spring emergence occurred during March - April. The longest movements occurred during May when snakes were moving away from brumation sites to summer habitat, after which movements decreased until a second peak in August. We did not find significant differences between male and female activity area, range length, total distance moved, daily movement, or distance from spring and fall brumation sites. However the core activity range of females was significantly less than that of males. During the active season, grassland habitat was used 75.6% of the time compared to habitats of grassland-shrubs (10.7%), hydrophilic vegetation (9.1%), woodlands (3.1%), and shrublands (1.5%). Identifying variations in a species spatial ecology is important for achieving long-term conservation goals because life history events, resource availability, and land management practices may have an effect on seasonal movements and habitat use. The results of our study demonstrate the need for, and some of the necessary data for, improved land management planning in order to meet conservation needs of the Western Massasauga in Nebraska.

Biogeographic consequences of shifting climate for the western massasauga (Sistrurus tergeminus)

“…With a potential shift north into South and North Dakota, and east into Iowa, Wisconsin, and Minnesota, this species could be tracking suitable climate into areas with considerable agriculture. Sistrurus tergeminus and many other grassland snake species are known to be absent from agricultural lands, preferring open grasslands across their range (Cagle, 2008 ; Mackessy, 2005 ; Patten et al, 2016 ). Unfortunately, grasslands in Iowa, eastern Minnesota, western Nebraska, and South Dakota are highly fragmented from agricultural development (Samson et al, 2004 ), and grassland connectivity across suitable climate is broken within the current and future range of S. tergeminus (McGuire et al, 2016 ; Figures S1.7 ).…”

“…Because sampling bias has been shown to result in biased estimation of environmental relationships, we created buffers with a radius of 100 km and 200 km around each point, merged each respective buffer into a polygon, and sampled random background points from the resulting polygons (Guillera‐Arroita et al, 2015 ). The 100 km buffer was a reasonable starting extent because it well encompassed known movement parameters for S. tergeminus (Patten et al, 2016 ; Wastell & MacKessy, 2011 ). The 200 km buffer accounted for a 76% increase in the background extent.…”