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Kazmaier, R. T., Hellgren, E. C., & Ruthven, D. C. (2002). Home range and dispersal of texas tortoises, gopherus berlandieri, in a managed thornscrub ecosystem. Chelonian Conservation and Biology, 4(2), 488–496. 
Added by: Admin (14 Aug 2008 20:35:29 UTC)   Last edited by: Beate Pfau (05 Jul 2009 08:31:54 UTC)
Resource type: Journal Article
BibTeX citation key: Kazmaier2002a
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Categories: General
Keywords: Ernährung = nutrition, Gopherus, Gopherus berlandieri, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Testudinidae
Creators: Hellgren, Kazmaier, Ruthven
Collection: Chelonian Conservation and Biology
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Abstract     
Gopherus berlandieri Testudinidae Southern Texas is dominated by Prosopis-Acacia mixed brush communities typical of the Tamaulipan Biotic Province, and the geographic range of the state-threatened Texas tortoise (Gopherus berlandieri) is nearly identical to the boundaries of this biotic province in Texas. In light of habitat fragmentation throughout southern Texas, we assessed home range use, movements, and natal dispersal of Texas tortoises at a managed site in the western Rio Grande Plains. Home ranges were larger for males (7-46 ha) than females (3-9 ha) regardless of method of home range calculation. Home range sizes determined by minimum convex polygon and bivariate normal methods were larger for individuals in ungrazed pastures (4-46 ha) relative to grazed pastures (3-15 ha), but home ranges derived from fixed and adaptive kernel estimators did not differ by treatment. Apparent treatment differences may be an artifact of an inability to adequately pair study areas given the scale of tortoise movement. Average distance between relocations indicated that males (74-153 m) moved more than females (31-41 m), but we did not detect differences in movement distances associated with grazing by cattle. Based on recapture distances of juveniles and adults, Texas tortoises appeared to exhibit male-biased natal dispersal. Our data suggest that Texas tortoises are highly mobile and may be capable of recolonizing across long distances following disturbance. Large home ranges suggest tortoises require large blocks of habitat to maintain stable populations. Populations of tortoises inhabiting small thornscrub fragments in the Lower Rio Grande Valley maybe constrained by patch size of available habitat and have reduced recruitment because of dispersal losses.
Added by: Admin  Last edited by: Beate Pfau
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