Timing, pattern, and extent of first prebasic molt of white-winged crossbills in Alaska

The timing, pattern, and extent of the first prebasic wing molt of White-winged Crossbills (Loxia leucoptera) were determined during a 6-yr banding study in interior Alaska. Hatching-year birds were not caught in substantial numbers until May, and all crossbills molted from juvenal to first basic plumage between September and December. A subsample consisting of 65 males and 55 females in first basic plumage was used to determine the pattern and extent of wing covert molt. On average, birds molted three greater coverts (GC) and retained two juvenal medial coverts (MC) per wing. The number of molted GCs was negatively correlated with that of juvenal MCs. Twenty-three percent of the individuals molted no GC, and no crossbill replaced all these feathers. The pattern and extent of covert molt was similar in males and females and was symmetrical in 69% of the individuals, but differed by one or two feathers in the remaining birds. Males in first basic plumage and with partially red or pink contour feathers molted more GCs and retained fewer MCs than males without contour feathers of these colors, although both groups apparently were of the same age. Remex molt was found in only one bird, which also showed partial proximal secondaries (=tertial) replacement.