The effect of habitat degradation on the long term survival of the Critically Endangered Madagascar spider tortoise (Pyxis arachnoides)

摘要: Abstract Pyxis arachnoides inhabits the dry, coastal forests of southwest Madagascar; a biologically unique ecoregion severely threatened by unsustainable small scale agricultural practices. Using remotely sensed data we established vegetation loss remains unabated within our study area at 1.2% year −1 ; consistent with wide between 1990 and 2000. We monitored tortoise population density on four occasions over 8 years developed stage class projection matrix to model finite growth rate, sensitivities elasticities population. Monitoring revealed an actual mean decline 10.8% 2003 2011. Our suggested rate be λ  = 0.986, indicative 1.4% for duration existence population, adult survival as most sensitive parameter overall Projection modeling suggests that would possibly become functionally non viable in approximately 170 years. As was heavily reliant use surrogate data, more information is needed pre-adult wild reproductive rates. site currently represents exceptional density, therefore, other less dense populations, subjected further stresses poaching will likely much sooner. This highlights utility matrices determining vulnerability chelonians; globally taxon. In case spider tortoise, well coordinated development programs tighter protected management are required address poverty induced drivers forcing this species closer extinction.