Well - I had to think about the coloration of the bill and lores for a
minute or two. The juveniles are more drab in the coloration of the
gular pouch - paler color than the adults. Their bills will also be
more black. Adult bills seem to get lighter as they age - more worn. I
don't think the bill and lore color would work that well, but I could be
wrong on this. I found a way to determine if a cormorant was a juvenile
for my purposes. I looked inside of their mouth and at their eyes.
Early in the breeding season adults have a bright blue (almost cobalt
blue) mouth. This coloration fades through the summer. The juveniles
have a gray mouth - no blue at all. Adults have a bright green eye, and
juveniles have a gray eye. I used the combination of these colors.
But, I was either capturing the cormorants or shooting them as part of a
diet study. So I had them all in hand. I don't think these
characteristics help when looking at them through a scope or
> Date: Fri, 10 Aug 2007 09:28:44 EDT
> From: - Maeve Kim <[log in to unmask]>
> Subject: more on cormorants
> Thanks, Adam, for your fascinating and informative post about cormorants. Now
> I want to look at cormorants more closely; I'd love to see the "leapfrog"
> I estimated that many of the birds in the raft I saw were juveniles because
> of the large amount of yellowish-orange near bill and lores, rather than the
> light breast. Is the bright color a good indicator?
> Maeve Kim
> Jericho Center