1999 Volume 48 Issue 2 Pages 145-150,165
Sexing without sacrificing or injuring birds is essential for field studies, though it is difficult to sex alcid species with no obvious sexual dimorphism or sex specific display. Rhinoceros Auklets Cerorhinca monocerata breeding on Teuri Island, Hokkaido, Japan had sexual difference in external measurements. A discriminant function was derived from external measurements of 34 male and 39 female breeding auklets. The sexes of the auklets could be separated by using the discriminate function D=114.22-3.25BD-0.64HL, where BD is bill depth and HL is head length. D was negative for males and positive for females. The efficiency of this discriminant function was 91.2% for males and 100% for females.
