Late Summer is for Studying Juveniles

by Bryce W. Robinson

Juvenile Western Sandpiper - Calidris mauri

Juvenile Western Sandpiper – Calidris mauri

Late summer in western Alaska is relatively slow birding compared to the early summer arrival of migrants and vagrants. Still, it holds potential for finding wayward migrants that head the wrong way, or get blown in from a storm. Additionally, even though most adult shorebirds are long gone, hoards of juveniles have taken their place. In some cases, this is the only place to see these juvenal plumages, as many of these birds will make a pre-formative molt prior to reaching their migratory stopover sites or wintering grounds. Juvenile shorebirds can be a challenge, so I’ve taken the opportunity to sift through what I find and make sure I recognize everything.

The bird above and the bird below are both juvenile Western Sandpipers – Calidris mauri, yet they appear quite different in bill length and patterning. I have seen this difference in multiple birds, and at times I’ve wondered if I am simply misidentifying the second bird. I am confident that this is just variation in the species. So, I’m putting these birds up and welcome any comments on their differences. I could be mistaken, it happens often.

Juvenile Western Sandpiper - Calidris mauri

Juvenile Western Sandpiper – Calidris mauri

At the moment it seems that the only shorebirds I see are juvenile Western Sandpipers. The density here on the Seward Peninsula is shocking. On occasion there will be a number of Semipalmated Plovers intermixed in the flocks, and even more uncommon are Baird’s. It seems Least Sandpipers haven’t made it to the coast yet, or are already gone. Time will tell. Rock Sandpipers and Dunlin have started moving through, but I haven’t seen a single Red Knot on the coast. The other day I did find two vagrant juvenile Greater Yellowlegs, a very good bird for western Alaska.

It has been fun searching for variation, all the while considering the timing of each species movements and their strategies for vacating the breeding grounds. Birding in western Alaska in late summer is enlightening, and provides a greater understanding of how these creatures manage themselves year round.

 

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