Joe Wetmore and I just returned from several days in the Provincetown, MA area. On Monday, while we were hiking to High Head Beach (North Truro) along the Cape Cod National Seashore, we witnessed what seems to be a fairly lightly documented phenomenon in that area: the massing of American tree swallows on their migration south. While the locals we later talked to mentioned that they frequently see a lot of tree swallows along the Cape in the fall, what we serendipitously encountered was really intriguing.
On our walk, as we crested the dunes and could see the ocean, we noticed large clouds of birds swirling overhead. The white bellies, calls, and flight patterns were a fast clue that these were tree swallows, these birds were surprisingly round. Well, fat. The birds all landed on the beach in a group, not far from the surf line, each one perched on the highest ridge of sand in the vicinity. The flock numbered about 3000. All sitting on the sand, facing south. Occasionally, they would startle, and most take to the air, only to settle down again. A naturalist on our whale watching trip later the next day congratulated us for seeing these birds, since he knew of few birders in the area who talk about these migration massings. When I checked eBird later that night, the records there resonated...sitings of 80, maybe a few hundred there. Ebird kicked my report back, in fact, asking me whether I'd actually seen 3000. The whale guide indicated that a little bit south in Wellflleet, he sees an estimated 100,000 there some years. After doing a little reading, it made sense. The swallows are gorging themselves silly on the lipid-rich bayberries that grow along the dunes, fattening up to fuel their long flights to southern wintering grounds. Bayberries are their second preferred food after insects. The following day at Race Point, we saw more flocks along the coast, looking from a distance like black haze moving along the shoreline, then coming in waves to the shrublands in back of the dunes, presumably to eat more. While this was just dumb luck to have seen what we did, I bet it would make a great research project for some enterprising student. I just count myself as fortunate, particularly when I thought the swallows living around the Finger Lakes had been gone for over a month already. Karen Edelstein -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
