[Tweeters] re: Great Blue Heron male/female distinction

Scott Downes downess at charter.net
Sun Mar 8 17:28:26 PDT 2009


I saw Kathy's message and looked again in Pyle. The exposed culmen, wing chord, tail length and tarsus all vary quite a bit by subspecies.
Lets take A.h. hrodias which breeds and winters in E WA (all measurements are in mm):
Female exposed culmen length is 123-148 while males is 129-156, considerable overlap exists and wouldn't be safely told in the field; wing chord is 432-471 for females, 441-495 for males, tail length is 159-184 for females, 166-190 for males; tarsus is 156-184 for females and 166-193 for males.
Measurements of A.h. wardi which I think is the W WA subpsecies are:
129-160 for female and 136-171 for males for exposed culmen, wing chord is 438-515 for females, 450-527 for males; tail length is 162-189 for females, 169-196 for males; tarsus is 159-214 for females and 168-224 for males.again considerable overlap. As Kathy mentions, males do average larger but considerable overlap exists. If you happen to have in hand these measurments would help to sex, but seems unlikely you could reliably sex on size alone in the field. Yes certainly behavior would be a key item that could help to sex.

Scott Downes
downess at charter.net
Yakima WA


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