The Role of Microhabitats in the Desiccation and Survival of Anurans in Recently Harvested Oak–Hickory Forest

Abstract

Juvenile survival is an important life history feature, because recent modeling efforts suggest that modest changes in juvenile survival rates due to habitat change may greatly affect population growth rates. We compared water loss and survival rates of recently metamorphosed American Toad (Anaxyrus americanus), Green Frog (Lithobates clamitans), and Wood Frog (Lithobates sylvaticus) juveniles contained within four microhabitats, two of which occur in uncut control forest (i.e., forest ridgetop, forest drainage) and two within recently harvested forest (i.e., clearcut open, clearcut brushpile). Survival was higher in forest drainage than forest ridgetop, indicating that microhabitats within continuous forest are not equally suitable. Brushpiles of coarse woody debris reduced desiccation risks in clearcuts as indicated by survival differences between clearcut open and clearcut brushpile and survival in clearcut open was very low for all species in both years. We found species differences in survival as well as a species by microhabitat interaction in water loss rates. These results are best explained by observed behavioral differences as opposed to physiological differences among species. We conclude that desiccation can be a major source of mortality for juveniles entering terrestrial habitats, especially habitat altered by anthropogenic land-use. Desiccation risks are greatest in areas with low soil moisture conditions, which for our study included microhabitats within clearcuts without coarse woody debris, forested ridgetops, and years with below average rainfall.