Literaturdatenbank
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Berry, K. H., Spangenberg, K. E., Homer, B. L., & Jacobson, E. R. (2002). Deaths of desert tortoises following periods of drought and research manipulation. Chelonian Conservation and Biology, 4(2), 436–448.
Added by: Admin (14 Aug 2008 20:35:24 UTC) |
| Resource type: Journal Article BibTeX citation key: Berry2002 View all bibliographic details  |
Categories: General Keywords: Gopherus, Gopherus agassizii, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Testudinidae Creators: Berry, Homer, Jacobson, Spangenberg Collection: Chelonian Conservation and Biology |
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| Abstract |
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Gopherus agassizii Testudinidae Droughts, or years in which precipitation falls below the long-term mean, are a frequent occurrence in the American Southwest. During or following droughts between 1990 and 1995, 11 (6 moribund, 5 dead) desert tortoises (Gopherus agassizii) were salvaged due to dehydration and starvation from three field sites in the Mojave Desert. The tortoises included 5 juveniles, 1 immature, and 5 adult males. Ten weighed 19.5 to 39.7% less than control animals, drought survivors of equivalent carapace lengths from the same or nearby study sites. In the weeks and months preceding salvage or death, the salvaged tortoises behaved abnormally for the season and weather conditions, e.g., not entering burrows for hibernation in fall, remaining above ground overnight exposed to freezing temperatures. In addition, rain sufficient to produce free-standing water fell in the vicinity of 9 tortoises, but only 4 showed evidence of drinking. Hematologic abnormalities included low packed cell volumes and heterophil counts. Abnormalities in the plasma biochemical analytes included hypocalcemia, hyperbilirubinemia, marked azotemia, and elevated sodium and chloride levels. Necropsy findings included atrophy or disappearance of the thymus, lack of subcutaneous fat adjacent to the proximal ends of the humeri, lack of coelomic fat, empty stomachs and upper intestines, and urolithiasis. Gross and histologic examination of tissues indicated osteopenia, skeletal muscle and liver atrophy, and mild to severe hemosiderosis of the liver. Other factors possibly exacerbating the debilitating effects of dehydration and starvation in 10 of 11 tortoises included young or old age, handling, research manipulation, and crowding in experimental desert enclosures. During droughts, scientists conducting research and procedures on wild desert tortoises can use abnormalities in behavior and laboratory data as early warning signs of stress and take appropriate actions to reduce impacts by modifying protocols, or delaying or terminating the procedures.
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