INTRASPECIFIC VARIATION IN WING LENGTH AND MALE PLUMAGE COLORATION WITH MIGRATORY BEHAVIOR IN CONTINENTAL AND ISLAND POPULATIONS

Interspecific comparisons have previously shown both a dullness in mal e plumage and a reduction in wing length of both resident and island s pecies compared with migratory and continental species, respectively. Intraspecific comparisons between subspecies were used to investigate whether these differences also occur within races of the same species and whether the effects of migration and island endemism are separate and additional, or identical, island endemics being resident. Continen tal migrant subspecies had both more colourful male plumage and longer wings than continental resident subspecies. Continental resident subs pecies were longer winged and tended to be more colourful than island resident subspecies. No difference in either coloration or wing length was found between continental migrant and island migrant subspecies. In a three-way comparison, the order continental migrant > continental resident > island resident was supported for both wing length and plu mage coloration. Intraspecific variation therefore parallels interspec ific variation in male plumage coloration and wing length, and the tra it reduction in island subspecies is additional to the reduction assoc iated with residency, but conditional on lack of migration. Possible d ifferences in natural and sexual selection pressures on coloration ens uing from insular and migratory life styles are discussed.