Food availability and primary feather molt in European starlings, Sturnus vulgaris

Abstract

The effects of food quality and overall food intake on molt have been experimentally investigated in a number of species. However, little is known concerning the influence of periodic food availability on molt parameters, although there are some associations in the field. In this study, we experimentally manipulated food availability through food deprivation during the molt of adult and juvenile European starlings, Sturnus vulgaris. By monitoring molt scores, wingtip shape, and lengths and length asymmetries of primary feathers during molt, we demonstrated that food deprivation can influence molt. Food-deprived juvenile starlings exhibited slower feather growth rates, although the duration and rate of molt were not affected. There were no differences in wingtip shape between food-deprived and control birds at the end of molt for either adults or juveniles. We also observed erratic reshedding of previously molted primary feathers in juveniles, although this did not appear to be related to the experimental treatments. The results of this study imply that feather growth rates and shedding rates are differentially affected by food availability: growth rates may be decreased when food deprivation occurs, whereas shedding rates are relatively unaffected.