During the chilly winds of Fall, whale-watchers are often surprised by the appearance of tiny, exhausted woodland birds, many miles out to sea. Tossed by gales and chased by gulls some of these birds find a temporary haven on boats.
Many northern songbirds winter far to the south of their summer breeding ranges. Getting to their wintering grounds, where food and weather may be more favorable (the exact reason for such migrations is still poorly understood), may be the most dangerous part of their year. For many, their flyway takes them out over the open sea.
Packing on fat by foraging for insects, seeds or berries, these tiny migrants strike out from promontories, taking short flights from cape to cape or longer journeys, far off shore and to the south (many fly east of Bermuda!). The songbirds seen flying over Stellwagen, likely came from Cape Ann, north of Boston, and may be heading for Beech Forest, Provincetown, Cape Cod or have been blown here by onshore winds. Once there, they feed voraciously, refueling for another flight south to Cape May, New Jersey (conversely, there is a lesser migration of songbirds in Spring as they head north).
The diversity of these birds can be astounding and their identification can be confusing. Many are woodland warblers in their fresh winter plumage of olive-yellow in these instances the sexes and species can look remarkably similar. Also, many species are in decline. As habitats in both their northern and summer habitats have been cleared and fragmented, song bird populations have crashed.
During Fall whale-watches, care should be taken for these great but tiny fliers. Often unafraid of people, they may hop about the decks unnoticed. If you spot one, point it out and keep an eye out (don’t let anyone step on them!). Most only want to rest a few minutes before moving on.
Partial list of species observed landing on boats during Fall Migration:
black-throated blue warbler
black-throated green warbler
Cape May warbler