Friday, May 24, 2013

Shorebirding on the Delaware Bay and an ID quiz of sorts

By Lukas Musher

On Tuesday I drove down to southern NJ to help David Mizrahi of NJ Audubon with his shorebird project that I worked on last year.  He didn't have me do any banding, bleeding, netting, or flagging.  Instead he had me go onto the beach and re-sight flagged Semipalmated Sandpipers.  The beaches are off limits this time of year due to shorebird migration, so I was very lucky to be able to get up and close with the birds themselves, and to get some phenomenal photographic opportunities.  

As I have talked about in the past, several species of shorebirds stage along Delaware Bay each Spring in coincidence with the spawning of the horseshoe crabs.  The fat-rich horseshoe crab eggs provide an invaluable calorie source for the migrating shorebirds, enabling them to finish their journey north to the breeding grounds in the high arctic.  

Fortescue is often one of the best places on the Delaware Bay shore to see the staging shorebirds, and that's where I was.  Above, you can see a few thousands shorebirds or several species (predominantly Semipalmated Sandpiper, Red Knot, Ruddy Turnstone, Sanderling, and Dunlin) roosting on the beach, and getting ready to begin feeding as the tide goes out.
Ruddy Turnstones are one of my favorite shorebirds, and what they lack in rareness, they make up for with charisma – or as Richard Crossley puts it, they are "the sausage dog of birds."
 Semipalmated Sandpipers greatly outnumber all other species, and yet they are one of the most severely declining shorebirds on Delaware Bay.  Red Knots are more famous, but in fact their numbers may be recovering, perhaps due to a strict moratorium on the harvesting of horseshoe crabs in the bay.  David Mizrahi has been studying this small and plain, albeit fascinating Calidris sandpiper for twenty years.  One of the biggest conservation concerns for this species has always been rampant hunting for food many countries throughout Latin America.

 I spent a lot of time scoping and sorting through the tens of thousands of birds looking for flags.  I found Red Knots from Argentina, Ruddy Turnstones and Sanderlings banded in previous years on Delaware Bay, and Semipalmated Sandpipers banded on the bay and two that were banded in Brazil.  I got tired of scoping, though, and took asylum behind the remnants of a disintegrating wooden fence covered in mold and algal residue.  It provided me with enough cover so that I could sit patiently as the shorebirds walked within ten feet of me allowing for fantastic photo ops.
A group of mostly Dunlin and Red Knot begin to take flight as I am noticed from behind the wooden remains.

A Semi banded on Delaware Bay!

One of several Red Knots I found that were flagged in Argentina!
Another D-bay Semi!

Exhausted by their long flights from South America and in preparation for the long flight to the arctic, Semipalmated Sandpipers recover and feed ferociously on the fatty crab eggs.

Incoming!  The Semipalmated Sandpiper landing on the right was flagged on Delaware bay by David's team.
Dunlin, Semi Sandpipers, and a Red Knot take flight, as the rest of the weary flock, including a couple of Short-billed Dowitchers, anxiously scamper forward.
Perhaps the most charismatic and infamous of North American shorebirds, a Red Knot in flight steals the frame from the other species taken to wing.
I may have spooked these Dunlin and Semis, but they know where they want to feed (AKA where the eggs are) and they come right back in to where they were before after two to three laps around the beach.
Finally, I leave you with a few photos of this bird.  I believe this to be a male Western Sandpiper, and upon consulting an expert, he agreed, though said he could not be 100% certain without photos of the underside.  I can tell you this, though, the bird was stockier and ever so slightly larger than the other Semis, and I remember thinking right away that it could be a Western based on build, rufous tones on the upper parts, and longer breast streaking than the typical Semi.  I welcome other opinions on this bird so feel free to post thoughts in the comments.  If it is a Western Sandpiper, this late date in NJ would make it very, very rare.  I will also be consulting more experts over the next few days, so maybe we can figure something out....most likely there won't be consensus.
Note rufous tones on scapulars, cheek, and cap, relatively long bill (though on the small side for Western, making it a likely male if confirmed), and blocky (not round like Semi) head.  I personally see some streaking making its way down the flanks, which Semi doesn't have.

He looks fat from this angle, more in favor of Western in my opinion.
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  1. A) Amazing, facemelting photos. I hope I get to see that spectacle someday.

    B) I like bright/heavily-marked Semipalmated (female) for that bird better than Western. Westerns have bright rufous tones that really pop out, even approaching red, which this bird is lacking. There are also no visible chevrons, which a bird in full alternate plumage like this one should have, even from the angles provided.

    1. Thanks, Steve. I'm glad you said that because several people including at least one fairly reliable source have told me Western, but a most trusted source from high up on Shorebird ID has told me he leans semi on the lack of chevrons alone!

  2. Hey Luke...

    That looks like a "rufous" Semi to me... my two cents...