Female Agassiz’s desert tortoise activity at a wind energy facility in southern California: The influence of an El Niño event
Natural Science
By: Josh R. Ennen, Kathie Meyer-Wilkins, and Jeffrey Lovich
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Abstract
We compared spring-summer activity of adult female Agassiz’s Desert Tortoises (Gopherus agassizii) among three consecutive years (1997, 1998, and 1999) that differed dramatically in winter rainfall and annual plant production at a wind energy facility in the Sonoran Desert of southern California. Winter rainfall was approximately 71%, 190%, and 17% of the long-term average (October-March = 114 mm) for this area in water years (WY) 1997, 1998, and 1999, respectively. The substantial precipitation caused by an El Niño Southern Oscillation (ENSO) event in WY 1998 produced a generous annual food plant supply (138.2 g dry biomass/ m2) in the spring. Primary production of winter annuals during below average rainfall years (WY 1997 and WY 1999) was reduced to 98.3 and 0.2 g/m2, respectively. Mean rates of movement and mean body condition indices (mass/length) did not differ significantly among the years. The drought year following ENSO (WY 1999) was statistically similar to ENSO in every other measured value, while WY 1997 (end of a two year drought) was statistically different from ENSO using activity area, minimum number of burrows used, and percentage of non-movements. Our data suggest that female G. agassizii activity can be influenced by environmental conditions in previous years.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Female Agassiz’s desert tortoise activity at a wind energy facility in southern California: The influence of an El Niño event |
| Series title | Natural Science |
| DOI | 10.4236/ns.2012.41006 |
| Volume | 4 |
| Issue | 1 |
| Year Published | 2012 |
| Language | English |
| Publisher | SCIRP |
| Publisher location | Irvine, CA |
| Contributing office(s) | Southwest Biological Science Center |
| Description | 8 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Natural Science |
| First page | 30 |
| Last page | 37 |
| Country | United States |
| State | California |
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