Diversity of feeding adaptations in certain columbid birds: A functional morphological approach.

ABSTRACT

With gradual increasing complexity in higher vertebrate structure and function, the birds as a class have acquired very high degree of feeding adaptations for diverse food-niches. A comparative functional morphological study of the feeding apparatus of 6 species of columbid birds showing diversification in their food-habits reveals that some correlations exist between the form-function complexes of the feeding apparatus and the extent of diversity of food-habits shown by these birds. Among the species of columbid birds selected for the Study, Columba and Streptopelia are ground feeders and predominantly grain-eaters, although quite often they invade diversified food-niches. Treron and Ducula, on the other hand, are almost exclusively fruit-eaters, plucking and swallowing fruits from the lofty tree branches, While Columba and Streptopelia show better kinesis of their jaws for ground-pecking, Treron. and Ducula possess wider gape as well as stronger grasp of their bill for plucking off, grasping and swallowing large-sized fruits. Consequently, the size and pinnateness of the jaw muscles in these fruit-pigeons have developed far greater than those observed in Columba and Streptopelia. Further, in Treron and Ducula, the thick and broad ‘venter externus’ slip of the M. pterygoideus ensures complete closure of the bill and possibly prevent any excess lateral expansion of the mandibular rami. Similar correlations have also been observed between the tongue features of columbid birds and the diversity of their feeding adaptation.