I don't know about GBHs, but I've seen many large flights of other herons,
egrets, and ibises at dawn and dusk, flying into roosting areas in the
evening and out to feeding areas in the morning. Some of them, as I
recall, were even in V formations. These have been at places such as the
Salton Sea and the Santa Ana NWR in Texas, in the winter or early spring.
I thought this was standard behavior for these waders. But how do you
know they were migrants? This sounds like residents' behavior, at least
at this time of the year.

Burt Guttman guttmanb at elwha.evergreen.edu
The Evergreen State College Voice: 360-866-6000, x. 6755
Olympia, WA 98505 FAX: 360-866-6794

"Have you ever noticed that you never see Rush Limbaugh and Barney the
Dinosaur together? Think about it!"