Browsing by Author "Becker, Francois Stephanus"

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    Searching for answers to the silent decline: first estimates of survival and recruitment for the critically endangered Rose's mountain toadlet, Capensibufo rosei
    (2014) Becker, Francois Stephanus; Tolley, Krystal A; Altwegg, Res
    Capensibufo rosei, a critically endangered bufonid found only within Table Mountain National Park, has shown a silent decline over recent decades, despite being found within a protected area with apparently pristine habitat. I estimated the first survival and recruitment rates for the species, using Capture-Mark-Recapture (CMR) methods, over a 7-year period, in order to identify demographic trends over time. I also used covariate models to test whether any observed trends in these demographic parameters were significantly related to variation in rainfall or drought-stress. I found some evidence for an extreme rainfall-induced life-history plasticity, with both survival and recruitment rates covarying closely with rainfall parameters. Although recruitment rate showed a positive relationship with rainfall, the relationship between survival rate and rainfall, specifically during the start of breeding, was negative, with breeding season rainfall explaining 94% of the variability in survival rate over time. I also found evidence to suggest that higher adult survival during poorer breeding rainfall years may be a natural population buffering mechanism to a highly variable microclimate, and that variable rainfall during the start of the breeding season may elicit a variable response in breeding investment by adults. Finally, I found evidence to suggest that the population is small, range-restricted and highly unstable, and that disturbances at the breeding site during good breeding years may cause the population to crash.