Adaptations for Food-Getting in the American Blackbirds

A careful study of the American blackbird family (Icteridae) during the past several years reveals that its members have invaded virtually every food niche exploited by passerine birds. The present investigation of the functional modifications of skull, bill, and jaw musculature in the 38 genera suggests that this success tems initially from a general pre-adaptation permitting an entirely new method of feeding. This paper describes first the individual feeding adaptations, then their convergent re-appearance in each of the three major icterid lines. Although the graphic comparison of the genera is presented in the form of a morphological tree of relationships in Figures 7 to 10, the full evidence for these relationships is not offered here. The present paper confines itself rather strictly to the nature of the adaptations themselves.