Barn swallows gathering on wires before fall migration

Why this time of year

This is the peak of the gathering: fall migration for barn swallows runs mid-August to mid-September, so every wire lineup in that window is a departure lounge that will be empty in three weeks.

How to notice it

1. Scan utility wires near fields, farms, and water for rows of small fork-tailed birds spaced like beads.
2. Count the row, then count again a few days later; the numbers swell as families join, then vanish.
3. Watch for feeding: youngsters on the wire still beg, and adults swoop past to stuff them mid-perch.
4. For the giant version, tree swallows stage along the coast in flocks estimated in the tens of thousands in big years; Parker River refuge on Plum Island is the classic evening show in late August.

Sources

• massaudubon.orgNear the end of August, as the last few fledglings leave the nest, families of barn swallows can be seen congregating on roadside wires, gradually joined by other adults and older young; fall migration extends from mid-August to mid-September, with occasional lingerers into October; winters in the Caribbean, Central and South America.
• massaudubon.orgDuring July and August, tree swallows start flocking along the coast and may be seen by the hundreds lined up on telephone wires near salt marshes; birds concentrate along the coastline in late August and September, with numbers at some locations estimated in the tens and hundreds of thousands in seasons of high abundance; during October the numbers shrink rapidly.
• audubon.orgSouthward migration begins as early as July and peaks in early fall; migrates by day, in flocks.
• fws.govIn late August, large numbers of tree swallows come to the Parker River refuge to feed on insects and berries before continuing to their winter ranges, forming large swarms of thousands as evening approaches.

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