Discussion: Puzzlement

First thing I thought of was eBird, where people (like PG) post sightings of birds at various locations. So I looked up Crane Beach.

I won't make any guesses, but this list should narrow the search down somewhat.

Maybe somebody saw them and will post. There were a gazillion of them, so they should have been pretty conspicuous.

Tree Swallows.

If you wondering why I say so, (1) I was at Plum Island a couple of years ago about this time, and there were thousands of them, (2) JJ's description is very accurate, and (3) well, this guy estimated 4,000 of them today at Crane Beach.

That looks exactly right. Thanks!