I have posted a compilation of images depicting some of the night flights and fall-outs of birds at Machias Seal Island.
The photographs span approximately 15 years and some of the pictures have been published previously. Some are as recent as last week.
Wow, I remember that one of the lighthouse...so envious.
And that's an interesting question, Bill, and I don't quite know how best to answer it.
The short answer is that MSI migration is no different from the mainland, except for the selection of species.
You could legitimately say that at MSI migration lasts 9 months.
About the only time of year that we don't have migrants moving in one direction or the other is December, January and February.
If you mean when do songbirds migrate, then the general period is early September to late October and again in early May through late June. Those periods refer primarily to passerines.
The biggest flights are seen roughly in the 2nd halves of May and September.