Blanchard's Cricket Frogs (Acris crepitans blanchardi) are geographically widespread and historically common, yet they are in decline throughout much of the northern part of their range. One proposed mechanism for this decline is the negative effects of acidified precipitation on this acid-sensitive species. To test the predictions of this hypothesis, we sampled 570 randomly-selected sites along three transects in Ohio using chorusing surveys during 2004. Along these transects, we assessed pH and acid neutralizing capacity (alkalinity), as well as terrestrial and aquatic vegetation cover. Our surveys detected 53 extant Cricket Frog populations (9.3% of surveyed sites) in ponds, lakes, and streams. These sites were exclusively located in western Ohio, indicating a substantial (120 km) range contraction, compared to its historic distribution in the state. A multiple logistic regression model found no significant relationship between Cricket Frog occurrence and either pH or acid neutralizing capacity (P > 0.50). Acid neutralizing capacity and pH were also not significantly different in extant and extinct areas of the Cricket Frog's range in Ohio (P > 0.05). Cricket Frogs were found to occur significantly more frequently than expected by chance in lakes and at sites with low canopy cover (P < 0.001). While synergistic interactions with other factors cannot be ruled out, these results suggest that habitat acidification is likely not responsible for Cricket Frog declines in Ohio. Unlike other declining amphibians, where likely causal mechanism(s) have been identified, causes of Cricket Frog declines remain enigmatic.
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Vol. 2006 • No. 2