Literaturdatenbank
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Ennen, J. R., Meyer, K., & Lovich, J. E. (2012). Female agassiz’s desert tortoise activity at a wind energy facility in southern california: the influence of an el niño event. Natural Science, 4(1), (in press).
Added by: Admin (29 Jan 2012 12:38:41 UTC) |
| Resource type: Journal Article BibTeX citation key: Ennen2012 View all bibliographic details  |
Categories: General Keywords: Gopherus, Gopherus agassizii, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Testudinidae Creators: Ennen, Lovich, Meyer Collection: Natural Science |
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| URLs http://www.scirp.org/journal/ns |
| Abstract |
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Testudinidae 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.
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