Feeding innovations and forebrain size in Australasian birds

Many authors have proposed that behavioural flexibility in the field is ass ociated with learning ability in captivity, relative forebrain size and rat e of structural evolution. In birds, the frequency of feeding innovations r eported in the short notes sections of ornithology journals may be a good w ay to operationalize flexibility. In this paper, we examine in the birds of Australia and New Zealand the relationship between forebrain size and inno vation frequency found in a previous study covering North America and the B ritish Isles. From a methodological point of view, the two variables are hi ghly reliable: innovation frequency per taxonomic group is similar when dif ferent readers judge innovation reports and when different editorial styles govern journals; relative forebrain size yields very similar estimates whe ther mean residuals from a log-log regression are used or ratios of forebra in to brainstem mass. Innovation frequency per taxon is correlated between the two Australasian zones and between these zones and the more northerly o nes studied previously. Innovation frequency is also associated with relati ve forebrain size in Australia and, to a lesser extent, in New-Zealand; in Australia, parrots show the high frequency of innovations predicted by thei r large forebrain, but yield no innovations in the New Zealand sample. The forebrain/innovation trend is independent of juvenile development mode, but phylogeny appears to be an important intervening variable in Australasia, as evidenced by non-significant independent contrasts.