Record Details
Giant gartersnake spatial ecology in agricultural and constructed wetlands
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Giant gartersnake spatial ecology in agricultural and constructed wetlands |
| Names |
Valcarcel, Patricia M.
(creator) Rosenberg, Daniel K. (advisor) |
| Date Issued | 2011-06-10 (iso8601) |
| Note | Graduation date: 2011 |
| Abstract | The spatial ecology of a species is a vital component of informed management and restoration plans, yet little is known about how animals use restored or constructed habitat. We assessed home ranges, core areas, and habitat selection of the federally threatened Giant Gartersnake (Thamnophis gigas) using rice agricultural habitat and recently constructed wetlands used as conservation banks. Space use patterns were estimated from radio tracking 19 unique adult female snakes over 2 years at a site that is the center of conservation efforts for the species. Home ranges (95% kernel density contour) and core areas (50% kernel density contour) were estimated for size, configuration, and overlap of the home range utilization distributions. Generalized linear mixed-effects models were used to assess habitat influences on microhabitat use. Contrary to expectations, but consistent across years, we found home ranges in the agricultural habitat were on average 80% smaller and had less variation among individuals than those in the constructed wetlands. Snakes in agricultural habitat also had greater and more uniform home range overlap as indicated by the utilization distribution overlap index. We combined all of the snakes to analyze microhabitat selection and used a matched location-random point design. Vegetation patch edges were used more often than interior locations in patches greater than six meters in diameter. This indicates that habitat complexity is an important consideration for habitat conservation plans. We were unable to detect differences in habitat use based upon vegetation composition at a small spatial scale. Temperature also influences reptile habitat selection, and a thermal description of the three macrohabitats (terrestrial vegetation, emergent vegetation, and open water) at our site showed extreme afternoon temperatures limit the use of terrestrial surface habitat by the Giant Gartersnake. The restricted home ranges observed in the snakes in agriculture suggest we need further investigation into dispersal movements and habitat connectivity to better inform regional conservation planning. Recovery efforts for the Giant Gartersnake, including construction and management of new wetlands, will benefit from greater knowledge of their space use patterns described by our research. |
| Genre | Thesis/Dissertation |
| Topic | spatial ecology |
| Identifier | http://hdl.handle.net/1957/21719 |
