Landscape complementation and metapopulation effects on leopard frog populations

For many species, not all required resources are contained in breeding habi tat. Such species depend on landscape complementation, i.e., linking togeth er different landscape elements through movement, to complete their life cy cles. We suggest that the dichotomous habitat classification of many metapo pulation analyses (habitat vs. nonhabitat) masks our ability to detect meta population effects for such species. We tested this using a species for whi ch landscape complementation is obligate and metapopulation structure is li kely: Rana pipiens, the northern leopard frog. We used breeding chorus surv ey data to index relative abundance of leopard frogs in 34 "core" ponds and conducted Poisson regression analysis to determine the effects on frog den sity of local pond habitat, availability of summer habitat (landscape compl ementation), and number of occupied ponds in the surrounding landscapes (me tapopulation structure). All of these factors had statistically significant effects on frog density. However, when summer habitat was not included in the statistical model, the metapopulation structure was no longer significa nt; i.e., its effect was masked. Our results suggest that one must be cauti ous in applying the results of metapopulation analyses to species for which the habitat vs. nonhabitat categorization of the landscape is not appropri ate. The potential for rescue and recolonization to maintain a regional pop ulation must be assessed within the constraints of the entire landscape.