Aging Fall-Shot American Woodcocks by Primary Wear

Abstract

The purpose of this study was to develop a method of aging fall-shot American woodcocks (Philohela minor) by examining wing feathers of known-age birds. Determination of age ratios of woodcocks has required examination of the intact bird for the presence or absence of the bursa of Fabricius (Greeley, 1953). The need for a method of determining the age of woodcocks from easily collected parts of the bird, such as wings, has prompted us to examine molting sequence critically. This was done in the course of summer trapping and banding activities in Massachusetts (Sheldon, 1955 and 1956). Through study of the molt, we discovered a variation in wing feathers of woodcocks which can be used in fall to determine age of the birds with a high degree of accuracy. Wings collected by Greeley (op. cit.) for his study of a sex criterion based on the width of the outer three primary feathers provided the bulk of the known-age hunting-season material by means of which we were able to check the validity of the technique. In the case of woodcocks, large samples of wings from fall-shot birds might well serve as a check on annual population estimates, which are currently based on counts of singing males in the spring. If there proved to be a significant difference in the production of chicks based on annual fall age ratios, such population changes presumably would be reflected in the following spring censuses. If such a calculation were planned on a regional basis, a large sample of fall-collected wings of both flight and resident birds would be required. In local areas in the northern extremities of the woodcock breeding range where the majority of fall-shot birds are residents, smaller samples of wings should suffice for comparing fall age ratios and spring counts. In any such analysis, the factor of weather should be carefully weighed. A prolonged freeze on the winter feeding grounds could inject a large error if an attempt were made to seek a correlation between fall age ratios and spring censuses.