This morning, 21 May 2017, I saw an empidonax flycatcher from the Turtle Pond Dock flycatching low on Turtle Pond Island. It was, by appearance, either a Willow or an Alder Flycatcher. The two species look almost exactly alike and can be differentiated in the field only by vocalization. This bird was quiet, and before I could play a recording that might elicit a vocal response it flew east. With the fence surround the adjacent lawn not yet open, I was unable to chase it and I went on with the morning’s birding walk.
Just after noon I returned to Turtle Pond. From the east-side landing (opposite the King Jagiello statue) I saw a flycatcher working over the marshy south shore. It flew across the pond toward me, and as it did, it began singing the characteristic “ritz-bew” song of the Willow Flycatcher. I heard another Willow Flycatcher respond faintly in song from the south shore as the first one continued singing near me.
This was the first time in six years of intense spring birding that I had ever heard a Willow Flycatcher sing in Central Park. I have heard them calling before, at least once every year since 2013.
I still have yet to hear an Alder Flycatcher sing in Central Park. Perhaps because its breeding range extends much farther north (compared to that of Willow Flycatcher) it is less likely to sing when passing through here. There is only one eBird report of Alder in Central Park that indicates song was heard. Other reports, which involve barely more than a handful of discrete occurrence dates over all time, mention call only.