I was in Cape May on Monday, and saw a similarly large flock of tree swallows, first gathering, then murmurating like starlings. I did not try to estimate numbers.
Here's a lousy iPhone video clip, barely hinting at the scale: https://www.facebook.com/suan.yong/videos/10210920362223036/ Suan -- 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/ --