Friday 2 October 2015

Re: [cobirds] Possible Arctic Tern, Chatfield Douglas, Co.

Here are some pictures of the juvenile plumage, Arctic Tern from Chatfield. 
 
 
He has been sitting on the end of the sandspit, taking off to fill up on gizzard shad and returning to the sandspit.  At first glance he could be overlooked as a Common Tern, but aging the bird helps determine it's ID.  The white secondaries with white-tipped, secondary coverts should not appear in any plumage Common Tern.  Additionally, Common Tern should show a dark secondary bar in all plumages except Alternate, which this bird clearly is not.
 
Glenn Walbek
Castle Rock, CO
 
 

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