The rescue effect and inference from isolation-extinction relationships

The rescue effect in metapopulations hypothesizes that less isolated patches are unlikely to go extinct because recolonization may occur between breeding seasons (“recolonization rescue”), or immigrants may sufficiently bolster population size to prevent extinction altogether (“demographic rescue”). These mechanisms have rarely been demonstrated directly, and most evidence of the rescue effect is from relationships between isolation and extinction. We determined the frequency of recolonization rescue for metapopulations of black rails (Laterallus jamaicensis) and Virginia rails (Rallus limicola) from occupancy surveys conducted during and between breeding seasons, and assessed the reliability of inferences about the occurrence of rescue drawn from isolation-extinction relationships, including autologistic isolation measures that corrected for unsurveyed patches and imperfect detection. Recolonization rescue occurred at expected rates, but was elevated during periods of disturbance that ...