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Kuchling, G., & Burbidge, A. A. , 49 years of mark-recapture of the critically endangered western swamp turtle (pseudemydura umbrina, chelidae) in southwestern australia - abstract. Unpublished paper presented at Program and Abstracts of the Tenth Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles. 
Added by: Admin (06 Jan 2014 18:22:54 UTC)
Resource type: Conference Paper
BibTeX citation key: Kuchling2012a
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Categories: General
Keywords: Australien - Australia, Chelidae, Fortpflanzung - reproduction, Habitat - habitat, invasive Arten - invasive species, Pseudemydura umbrina, Schildkröten - turtles + tortoises, Zeitigung - incubation
Creators: Burbidge, Kuchling
Collection: Program and Abstracts of the Tenth Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles
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Two Pseudemydura umbrina populations, at Twin Swamps Nature Reserve (TSNR) and at Ellen Brook Nature Reserve (EBNR), near Perth, Western Australia have been monitored by mark-recapture since 1963. P. umbrina lives in seasonal swamps and is only active in standing water during winter and spring. The turtles are carnivorous and eat live aquatic invertebrates and tadpoles. These cryptic and hard-to-find turtles never enter baited hoop nets. They can only be successfully trapped by drift fences, but trapping at TSNR by drift fence and pit falls from the mid-1960s until the late 1970s exposed trapped turtles to predation by the introduced Red Fox (Vulpes vulpes) and was discontinued when the population crashed in the late 1970s. Today the main method of capturing P. umbrina is by searching and paddling in swamps, which means the proportion of individuals captured per year is low and annual population estimates can vary dramatically. The best results are obtained by Manly and Parr estimates using known age corrections and directly by known to be alive (KTBA). The TSNR population crashed from about 200 individuals in the mid-1960s to less than five by the late 1980s. In addition to fox predation, a major reason for the decline appeared to be south west Australia’s drying climate. Re-introduction of captivebred turtles following management improvements (fox control and a fox exclusion fence, groundwater supplementation of swamps) from 1994 onwards increased numbers, but recruitment was extremely low until 2011 when better groundwater pumps allowed more aggressive swamp supplementation. In contrast to the TSNR population P. umbrina numbers at EBNR remained fairly static in the low 20s from the 1960s to the early 1980s. An apparent slow increase of turtle numbers during the 1980s is probably due to the inclusion of an additional monitoring area since the late 1980s, but management improvements since 1991, including a fox-proof fence, helped the population on to a slow increase trajectory. Despite this the juvenile population (not adults) crashed in 1996/97, likely due to a meso-predator release of bandicoots Isoodon obesulus, the numbers of which are now controlled by trapping and release elsewhere.
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