COMPARATIVE MECHANICS OF BILL, CLAW, AND FEATHER KERATIN IN THE COMMON-STARLING STURNUS-VULGARIS

The Vickers microhardness of non-melanic keratin was measured from the bills, claws and outer primaries of Common Starlings Sturnus vulgaris . Highly significant differences in hardness were found between all th ree keratin types. Bill keratin was the hardest and feather keratin th e least hard; the relative molecular weight of the different keratin t ypes may explain these differences. Indentation hardness can be used a s a measure of the competence of a material to resist abrasive wear so it is likely that the three keratin types differ in their competence at resisting abrasive wear.