Literaturdatenbank
Literaturdatenbank |
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Randriamahazo, H., Traylor-Holzer, K., Leus, K., & Byers, H. O. , Population and habitat viability assessment. Paper presented at Workshop for Endemic Tortoise Species in Madagascar Geochelone radiata (Madagascar radiated tortoise) Pyxis arachnoides (spider tortoise).
Added by: Sarina Wunderlich (18 Nov 2012 17:43:52 UTC) |
| Resource type: Proceedings Article BibTeX citation key: Randriamahazo2007a View all bibliographic details  |
Categories: General Keywords: Astrochelys, Astrochelys radiata, Habitat = habitat, Madagaskar = Madagascar, Pyxis, Pyxis arachnoides, Schildkröten = turtles + tortoises, Testudinidae Creators: Byers, Leus, Randriamahazo, Traylor-Holzer Collection: Workshop for Endemic Tortoise Species in Madagascar Geochelone radiata (Madagascar radiated tortoise) Pyxis arachnoides (spider tortoise) |
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| URLs www.cbsg.org |
| Abstract |
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Testudinidae Geochelone radiata Pyxis arachnoides For both tortoise species, population models based on the best available data project substantial tortoise population decline in the face of illegal harvesting. All scenarios tested based on current estimated harvest rates project that the radiated tortoise population will continue to decline to extinction, likely within 50 years. Likewise, two of the three spider tortoise populations are projected to disappear in 60-80 years at current estimated harvest rates. If spider tortoise harvesting increases as large radiated tortoises become rarer, population decline could accelerate toward earlier extinction. Although better data on tortoise biology, population size and harvest rates would allow refinement of these projections, they are unlikely to reveal that these populations are viable unless harvesting is greatly reduced. Tortoise population decline is being driven by over-harvesting, which currently overshadows the effects of habitat loss and fragmentation. Harvest rates for radiated tortoises may need to be reduced by 85% or more to halt this population decline. With the current population and harvest estimates, this translates to a loss of no more than about 9,000 radiated tortoises and 3,000 spider tortoises per year. Conservation actions that serve to significantly reduce the number of tortoises harvested will be necessary to ensure the persistence of viable tortoise populations into the future. Habitat conversion, fragmentation and other threats to the tortoise population should also be addressed, as they also affect population viability, especially if harvesting is not completely eliminated. It is likely that no single conservation action will sufficiently protect tortoises; therefore, multiple effective conservation efforts will be needed to ensure the long-term persistence of this species.
Added by: Sarina Wunderlich |