I liked watching the swallows’ acrobatics in the sky as they’d dart, swoop and snatch bugs in mid air. I put up two of your Wild Birds Unlimited birdhouses 30 feet apart because you said that way I might get both a bluebird and a swallow. I did! The bluebirds are almost done with their second nesting. The swallows only nested once and then a chickadee moved in. I haven’t seen the swallows since. Did I do something wrong?
Not at all, it sounds like you had a very successful nesting season. Tree Swallows are typically single-brooded, although they may attempt a second nest if the first fails. After nesting they gather in wetlands where they build their reserves by feeding on insects to prepare for their journey south. Most leave Michigan by mid-August. They migrate in loose flocks by day and gather in large groups to roost at night. With the first signs of autumn, they migrate until they reach their wintering grounds which stretch from North Carolina, the Gulf Coast, and Southern California to Cuba and Guatemala.
Tree Swallow Tachycineta bicolor
Order: PASSERIFORMES Family: Swallows (Hirundinidae)
Description: Tree swallows have iridescent greenish-blue on their head, shoulders and back, and a white underside. They have a short black beak and dark brown feet. Young tree swallows look similar to adults, but they are brownish above instead of greenish blue.
General: Tree Swallows arrive in mid-Michigan in March. They prefer open areas in the sun, pastures, fields and golf courses and nest in natural tree cavities, or man-made nest boxes, including those built for bluebirds. The bluebird and swallow are both native species and both desirable birds to have in your yard. One proven technique that allows both songbirds to nest together successfully is to set up pairs of boxes, no more than 10-20 feet apart. Since Tree Swallows will not allow another pair of swallows to nest within 20', the second box is free for bluebird use and the two species can co-exist, after some initial squabbling to sort out who gets which box.
Behavior: Tree swallows do not spend much time on the ground. They can often be seen perching in long rows on wires. They also spend much of their time in flight.To bathe, swallows swoop down over a body of water and lightly brush the water. To eat swallows catch mostly winged insects while in flight, but can forage on the ground for insects, spiders, seeds, and berries. A group of tree swallows are known collectively as a "stand" of swallows.