FEEDING INNOVATIONS AND FOREBRAIN SIZE IN BIRDS

The links between ecology, behavioural plasticity and brain size are o ften tested via the comparative method. Given the problems in interpre tating comparative tests of learning and cognition, however, alternati ve measures of plasticity need to be developed. From the short notes s ection of nine ornithological journals, two separate, exhaustive data sets have been collated on opportunistic foraging innovations in birds of North America (1973-1993; N=196) and the British Isles (1983-1993; N=126). Both the absolute and relative frequencies (corrected for spe cies number per order) of innovations differ between bird orders in a similar fashion in the two geographical zones. Absolute and relative f requency of innovations per order are also related to two measures of relative forebrain size in the two zones. The study confirms predicted trends linking opportunism, brain size and rate of structural evoluti on. It also suggests that innovation rate in the held may be a useful measure of behavioural plasticity. (C) 1997 The Association for the St udy of Animal Behaviour.