Tree Swallows are Michigan's early swallows — iridescent teal-blue above and immaculate white below, wheeling over half-thawed marshes by late March, weeks before other swallows dare return. Their secret is dietary flexibility: when a cold snap grounds the insects, Tree Swallows can survive on bayberries and other fruit.
They're cavity nesters, and the bluebird-box boom has been a windfall for them — many "bluebird trails" fledge as many Tree Swallows as bluebirds. Pairs line their nests with feathers, and in late summer they stage in spectacular thousands over Great Lakes marshes before heading south.
Flying insects caught in fast, gliding pursuit over water and fields. Uniquely among our swallows they also digest berries, which lets them arrive earlier and linger later than insect-only relatives.
No — they're a native, protected, and beneficial species. The standard fix is pairing boxes 15–25 feet apart: swallows defend against other swallows, so one pair of each can nest side by side.
They hedge with fruit. Bayberry and other waxy berries can carry them through cold snaps that would starve other swallows — the payoff is first claim on the best nest cavities.
Insulation — feather-lined nests keep chicks warmer and fledge more young. Adults will chase a drifting white feather like a prize; tossing a few out on a breezy day near a colony is great entertainment.
First arrivals show up in March, numbers peak from May through July, and the last birds clear out during November. Outside that window Michigan has none.
Juveniles are gray-brown above with a soft dusky breast band. Females are also brown for their entire first year and only become glossy blue-green in their second — a delayed plumage unusual among songbirds.
Enormous ones. After nesting they mass in staging flocks over marshes and shorelines, and roosting flights in late summer can involve tens of thousands of birds funneling into a cattail marsh at dusk.
Other birds you might be looking at instead.
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