For the Birds Radio Program: Swallow Migration
Swallow migration is peaking. How do you recognize the different species?
![Cliff Swallow] (https://farm4.staticflickr.com/3603/3369506200_4d251614de.jpg “Cliff Swallow”) (Recording of Purple Martins)
One of the first signs of summer’s end in the northland is when the swallows gather. Families of most species of swallows have left their nesting areas to sit shoulder to shoulder in big congregations along power lines, although Cliff Swallows are still feeding babies in their little mud houses under the eaves of Twin Ports buildings.
There are six species of swallows in the Midwest, and August is a good time to study them. All swallows have short beaks with a very wide gape–it makes it easier to catch flying insects, which are the only food of most of these birds. Their flight is distinctive–strong and graceful on long, pointed wings. All of our swallows except the Cliff Swallow have notched or deeply-forked tails.
The largest swallow in North America is the Purple Martin. Males are iridescent purplish-black–the only swallow that is dark all over. Females and young are browner on their backs, with a dusky breast and a light belly. Except for their size, they look quite a bit like another species, the Rough-winged Swallow. Rough-wings dig burrows in river banks or in drainpipes at bridges, so they’re common in spring and early summer along the Lester River, at Chester Bowl, and other Duluth parks. But now they are joining the other swallows in a feeding frenzy, fueling up for their flight down to Central and South America.
The swallow most likely to be confused with the Rough-winged Swallow is the Bank Swallow–both are small, with notched tails, brown backs, and white undersides. But where the Rough-wing has a dusky area on its throat and upper breast, the Bank Swallow has a white throat and a dark, thin chest band which conveniently looks exactly like the slot of a piggy bank. Like Rough-winged Swallows, Bank Swallows burrow into banks for nesting, but Bank Swallows are gregarious, nesting in large colonies–Rough-wings are more solitary breeders.
Adult Tree Swallows are well-known by anyone who sets out bluebird houses–they are snowy white beneath, with iridescent blue or green backs. But young Tree Swallows are brown-backed, which confuses a lot of novice swallow watchers. No matter which plumage they’re in, all Tree Swallows are bright white on their undersides, from their beak to their undertail coverts–if they have any dusky area at all on their breast, it is diffuse and pale.
Barn and Cliff Swallows are the two species which nest on or in buildings, and both are the only swallows with rusty parts–on the Barn Swallow’s face and underside, and on the Cliff Swallow’s face and rump. Barn Swallow’s have a deeply forked tail–even very young ones have a noticeable notch. Cliff Swallows all have a square tipped tail. Barn Swallows generally build their mud nests on some kind of supporting structure–like rafters inside barns. Cliff Swallows generally plaster their nests beneath an eave. They are a favorite sight of many tourists and local people, and eat a tremendous number of mosquitoes, although the people who try to keep their buildings immaculate often find Cliff Swallows hard to swallow.
(Recording of Cliff Swallows)
Ths is Laura Erickson, and this program has been “For the Birds.”