Friday, March 23, 2012

Dark-eyed Junco migration

The Dark-eyed Junco Junco hyemalis is a medium-sized sparrow with dark gray plumage on its head, breast and upper parts which contrast with the white, outer tail and white belly. The female and immature juncos are less slate colored and tend to be browner than the adult male.

In mid-Michigan, it's almost time to say good bye to the juncos. These small birds prefer cold climates to nest, so they retreat north as spring arrives.

The juncos we see all winter in the Lansing area are typically males. Studies show winter junco flocks are 80 percent male in Michigan and 72 percent female in Alabama. Males risk harsh winters in the northern states in order to be the first ones back to their upper Michigan and Canadian breeding grounds to stake out a territory in the spring. As the days get longer and warmer, the boys migrate north.

So now in early spring, the jucos we see are mostly female. Once they fuel up they may linger a few days or continue north if the weather cooperates. You won't know until the next morning who you'll host for breakfast.

Juncos migrate at night at very low altitudes in flocks up to 100 individuals. Other birds like fox and tree sparrows may accompany the juncos. Flock composition can change from day to day during migration. Juncos prefer to forage and roost in groups during the day and may depart en masse at night but do not stay together during flight.

Juncos, like many other members of the sparrow family, eat a variety of insects and seeds mainly on the ground. What seeds they prefer can differ across the country.

Black oil sunflower seeds, millet, safflower, peanuts and peanut butter suet are some of the most popular foods that attract juncos to tray or ground bird feeders.
You’ll also see the juncos scratching for grass seeds or insects in leaf litter and pine needles.

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