A technique is described for separating adult from juvenile ring-necked pheasants (Phasianus colchicus), from measurements of the shaft diameter and total length of the first primary. The pheasant is one of a few Galliformes to molt all ten primaries during their postjuvenal molt (Petrides 1942:323). Most other gallinaceous game birds retain the outer two juvenal primaries and these feathers are commonly used for separating adults from juveniles. The complete molt of primaries in pheasants has apparently caused investigators to abandon the wing and look elsewhere for age separation between adults and immatures. Ideally, an age criterion should be quantitative and have no overlap between ageclasses. Stokes (1957), and Gates (1966) have shown, for example, that age determination from spurs of male pheasants does not meet either of these standards. Not only do spur lengths overlap, but there is overlap in qualitative characteristics as well. The bursal-depth technique (Linduska 1943) has remained the most reliable aging method for pheasants described to date. However, one of the main weaknesses of both the spur and the bursa as aging criteria is that their reliability becomes questionable after midwinter, that is, the length of the spur of This content downloaded from 157.55.39.210 on Sat, 30 Jul 2016 05:19:26 UTC All use subject to http://about.jstor.org/terms AGING PHEASANTS BY PROXIMAL PRIMARY MEASUREMENT * Wishart 715 Table 1. Comparison of post-juvenal primary 1 measurements of male and female ring-necked pheasants sampled at 16-18 weeks in October, and 48-50 weeks in May. DIAMETER OF PRIMARY 1 (MM) LENGTH OF PRIMARY 1 (MM) AGE-SEX CLASS N x SE Range N x SE Range Male (16-18 wks) 109 3.06 ? 0.01 2.76-3.38 108 163.5 ? 0.42 153-175 Male (48-50 wks) 76 3.05 +0.01 2.84-3.29 62 164.1 + 0.56 155-176 Female (16-18 wks) 100 2.79 0.01 2.60-3.03 100 148.7 ? 0.50 138-161 Female (48-50 wks) 100 2.77 + 0.01 2.40-3.00 82 149.0 ? 0.52 139-160 juveniles progressively continues to increase and the depth of the bursa of juveniles continues to decrease as the bird becomes older. The purpose of this study was to investigate the use of proximal primaries as age criteria in pheasants. The proximal primaries were selected because, as post-juvenal feathers, they are completely grown at about 10-11 weeks and are retained for approximately 1 year (Westerskov 1957:2627). Although the proximal post-juvenal primaries are adultiform, their growth is completed by a bird that is approximately one-half adult size (Westerskov 1957:29). Thus, the proximal post-juvenal primaries are unlikely to be as large as the proximal postnuptial primaries which are grown by adults about the same time of year. I am indebted to J. Pelchat, Alberta Fish and Wildlife Branch, for the care and maintenance of the experimental birds. I wish to thank R. Finegan, B. C. Fish and Wildlife Branch, B. Murray and E. Ewaschuk, University of Alberta, and Janis Hall, formerly of the Alberta Fish and Wildlife Branch, for their assistance in taking several thousand wing measurements. I am grateful to F. C. Zwickel, University of Alberta, for his critical reading of the manuscript.