Most migrants stop in the morning to feed and rest and then resume their journey at dusk. It's a perilous journey with many obstacles. Most song birds live about two years with about 85% of the mortality occurring during migration. For example the tall glass towers in Toronto form a lethal barrier for birds coming south across Lake Ontario from the northern wilderness.
The multitudes of migrating birds are most easily seen on weather radar. The Wordpress Badbirdz Reloaded site provides a good primer. There are several ornithologists that chart the nightly migration progress on their blogs. Drew Weber of Nemesis Bird is one of them.
In New England by October most of the warblers have left, but there are still a few stragglers. The highlight of my recent walk was seeing an Orange-crowned Warbler, a life bird for me. Among the sparrows skulking through the underbrush I glimpsed a small bird with a delicate beak. Pishing brought it to the surface.
The name is really a misnomer. The orange on its crown is almost invisible except in a certain light.
It's a late migrant that may stay into November and may even turn up during a Christmas Bird Count.
The Palm Warbler is another such species that is still around in NE. I took these photos in early October on the West River Trail:
On the same day I found a female Blackpoll Warbler, a species usually found in the higher altitude of the White Mountains - see previous post.
Blackpoll Warbler undertake the longest migration of any warbler according to BNA online. Their route takes them south across the Atlantic Ocean, a route that averages 3,000 km and may necessitate a nonstop flight of 88 hours.
The Ruby-crowned Kinglet is another late migrant
If you like to read more about bird migration here are two remarkable books: