Migrating blue jays pay a visit to a Minnesota backyard

There were 13 blue jays in our yard one day in late September, some of them surely migrants from points north. By Oct. 21, the total number of migrant jays counted from Hawk Ridge in Duluth, heading south, was 59,561, 23 percent of all birds tallied.

Seven of our 13 apparently ate and flew, migrants maybe. Six jays returned the next day.

That sextet might have been a family group; it included two juveniles. All were coming to feeders on our deck. They were attracted by whole peanuts, corn kernels and sunflower seeds.

The food was put in four clay flower pots sans flowers, held by a metal rack hanging on the deck rail. Feeders are what you make them.

The jays were caching, hiding food for use this winter. Cornell Labs' monograph on this species says a single jay could stash thousands of food items in winter prep.

Jays would be hiding acorns, a favorite food, if our neighborhood had any oak trees. They'd prefer to pick their own, fresh as opposed to fallen.

They have no hesitation, however, about peanuts and seeds in old flower pots, being very willing to use acorn substitutions. (But they're not going to get thousands of peanuts in the shell.)

If peanuts were acorns jays could take as many as five per trip, according to research. Two would be lodged in the throat, two in the mouth, and one held tight in the bill. Can't do that with peanuts in the shell.

Sunflower seeds or corn kernels? A delivery load easily reaches double figures.

We'll assume the birds would not make the caching effort if they intend to migrate.

Some jays migrate, others don't. Migration destinations can be close, the next county south or distant as Texas. These birds don't leave the country, though.

Blue jays make migration flights during the day — diurnal is the term for daytime behavior. Studies show the birds begin flight shortly before dawn and quit for the day at noon.

Bird feeders are thought to help some jays overwinter in their home territory.

The migrants that came through Duluth are believed to be making the trip this fall because of a shortage of acorns to the north. Oak trees fruit on a 2-5 year schedule, sometimes a bumper crop, other times slim pickings.

In addition to the variety of nuts you might find in a holiday assortment, blue jays eat fruit, insects, snails, bats, tree frogs, bird eggs and nestlings. And dry dog food. And other things.

Minnesota has two species of jay, the blue and the gray. Gray jays are birds of the boreal forest.

North America has other jay species: Steller, island scrub, Western scrub, Florida scrub, Mexican, green, brown and pinyon. Most are western residents.