Saturday, December 5, 2015

'Western' Flycatcher in Central Park, New York

So mid-week a birder posted a sighting of a Yellow-bellied Flycatcher in Central Park.  Birders who saw the post raised an eyebrow.  While not an impossibly late date, an empidomax this late in November should perhaps more logically be a Western vagrant than a late Eastern migrant, so multiple birders went out and searched for the bird the next day but unfortunately didn't re-find it.

Red-headed Woodpecker
Fast forward to Friday, and the bird was finally re-found and re-identified as a 'Western' Flycatcher.  At least one photo was taken and the eye-ring and wing details pretty much clinched it as a 'Western'. So the word got out and the hunt was on.  This was a super-rare bird for New York State and the crowds were sure to gather on Saturday.

'Western' Flycatcher used to be a species but in 1989 it got split into Pacific-Slope Flycatcher and Cordilleran Flycatcher.  The two species are notoriously difficult to split based on plumage and it's a brave birder who splits them away from breeding territories.  Generally the IDs rely on song - Cordilleran is slightly more 'buzzy' but Winter birds rarely call, let alone sing, so this was going to be an ID challenge.

On Saturday morning I was out in East Hampton meeting with contractors, and buying a new wine fridge (well you can't store your Bollinger in any old wine fridge and I settled on the Viking model).  I was itching for news though and sure enough Adrian Burke posted that he'd re-found the bird mid-morning,  By 10:30am I was on the road, and after struggling to find a place to park on the upper east side, got to the Ramble area of Central Park by about 1pm.

As I walked into the Park I bumped into Tom Burke and Gail Benson who told me that the bird had been seen well all morning but had vanished about a half hour ago (!) this does seem to be a pattern when I twitch things.  Undaunted, I headed to the site and spent two hours looking for it, drawing a blank but at least getting some intel (including speaking with Isaac Grant who had heard the bird sing and was settling on a Pacific-Slope ID).  When my parking meter was up though I had to move on (2 hours in New York FYI) so I went to the NYC apartment and settled in to do some work.  Moments later I got the text that the bird was being seen again (oh, come on!) but it was too late to go back so I made plans to try again on Sunday.

While I couldn't see the bird, I could study about it, and I learned a lot.  It turns out that calls in the field aren't really all that useful other than a few distinct contact notes (and you really need some serious technology to be sure about that).  Plumage differences are also not helpful.  In addition, recent analysis has found a fairly significant overlap zone with lots of hybridization - the California birds may well be Pacific Slope, the Colorado birds may well be Cordilleran, but to the North, many birds are integrades.  To cut to the chase, this probably isn't a good split and it probably isn't going to stay split for ever.  But in the meantime, to get it on the state list required an ID.

Sunday morning I went in early to the Park and started a search pattern, visiting all the spots where the bird had been seen the day before.  I was there by 7:30am but by 8:30am I was still drawing a blank.  I met up with Brent Bomkamp and we continued to check the previous locations while catching up on past years of Long Island birding and seeing a Red-headed Woodpecker (scarce in New York).  We were still chatting when Brent looked up and shouted, "There .. that's it" and a small yellow bird flitted over our heads and vanished behind one of the (curiously covered) fences that have been set up as part of a Ramble rehab program.  The flycatcher stuck around and even though we were initially peering through a fence we could get all the details we need to make sure we had the right bird.  Deb Allen quickly joined us, and both Brent and I took a quick break to post on the New York State Listserve (Brent) and the Central Park text alert (Me).  But when we looked up, the bird was still there, on our side of the fence and Deb was able to get some good photos.

Two shots by Nathan Remold (used with permission)

Once we got the word out, lots of birders came over and saw the bird.  It didn't look all that healthy to be honest but it was actively feeding.  So we all got good views, and the crew of Cornell birders that came down got good audio recording and even took some 'poop' away to do a genetic analysis.  I saw the bird defecate once but unfortunately on the wrong side of a fence.  Later that day, an enterprising Cornell birder jumped a fence and managed to scoop up an oak leaf with some feces on it and spirited it away to Cornell. The analysis is apparently scheduled for next week (a DNA kit has been ordered).

In the meantime, the sonograms strongly suggest Pacific-Slope Flycatcher contact note, but I guess we'll see what the science comes up with.  Doubt the bird will be accepted by the NYS Avian Records Committee but its fascinating to see the process unfold and see the experts try to to pin down this ID.  Hoping that the young guns at Cornell work this out.

Best portrait I've seen of the 'Western' Flycatcher - by Deb Allen (used with permission)

My hunch on this bird is Pacific Slope - based on what I heard.  But I guess we'll have to wait on the analysis to see what happens.

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