Survival costs associated with wood frog breeding migrations: effects of timber harvest and drought
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Ecology. 90(6): 1620-1630.
Migration presents a trade-off for individuals between the potential fitness benefits of reaching high-quality habitat vs. the potential costs of migration. Within an information-theoretic framework, we examined the costs of migration for adult wood frogs (Rana sylvatica) in response to timber harvest and annual weather conditions using Cox proportional-hazard estimates of survival. In 2004 prior to timber harvest, survival did not differ between the inside (0.75, SE = 0.078) and outside (0.73, SE = 0.235) of the circular timber harvest arrays (each 164 m radius). Following timber harvest, survival inside arrays in both 2005 and 2006 (0.22, SE=0.065; 0.42, SE=0.139) was lower than survival outside of the arrays and prior to harvest. Sources of mortality included predation in all years and desiccation in the drought year of 2005. The most-supported models for explaining both predation and desiccation risks reflected behaviors as opposed to timber harvest or weather conditions. Both predation and desiccation risks increased when frogs made frequent movements or were located near breeding ponds.
Keywordsanuran desiccation drought predation radiotelemetry Rana sylvatica timber harvest wood frogs
Rittenhouse, Tracy A.G.; Semlitsch, Raymond D.; Thompson, Frank R. III. 2009. Survival costs associated with wood frog breeding migrations: effects of timber harvest and drought