Ecological correlates of social learning: problems and solutions for the comparative method.

Interspecific variation in learning and cognition is often accounted for by adaptive specialization, an ecological framework where variation between species in the environmental problems they face is thought to select for quantitatively and/or qualitatively different abilities. Adaptive specialization theory relies on the comparative method for testing its hypotheses and assumes a naturally selected basis for the predicted differences. This review examines social learning as a specialization to group-living and scramble feeding competition. It points out one important problem with current studies in the area, the lack of quantitative controls for confounding variables that may cause type 1 or 2 error in comparative tests. A linear regression technique is proposed to measure and remove interspecific differences on control tests for which there is no predicted adaptive specialization; as in other areas of comparative biology, the adaptive prediction is then made on the residual deviation from the regression of these confounding variables. Examples are given from research on opportunistic Columbids, the group-living feral pigeon Columbia livia, and the territorial Zenaida dove, Zenaida aurita.