Modelling factors affecting population trends in an endangered amphibian

摘要

Severe recent declines of amphibians around the world have highlighted the need to identify factors that affect their population dynamics and viability. This study used a long-term (> 30 years) dataset collected for a British population of natterjack toads Bufo calamita, a rare and endangered species in much of northern Europe. Modelling was employed to test a series of hypotheses concerning the effects of anthropogenic (conservation management) and climatic factors on toad demographics. The best models accounted for > 72% of the variance in population size, as judged by spawn string counts, between 1975 and 2007. Conservation management (pond creation) was important, as were spring and summer climate variables relating to larval survival, and winter conditions associated with hibernation mortality. The implications of trends associated with future climate change are also considered.