Songbirds pour on the speed to get back to Minn. in spring

Baltimore orioles, rose-breasted grosbeaks, flycatchers, phoebes, swallows and many other birds are due back right about now. Since many of Minnesota's migratory birds must travel thousands of miles to get here, you'd think it would take them a fairly long time to go the distance.

Think again.

Scientists have recently discovered that some migrating birds put on the speed to reach their summer homes.

Canadian researchers placed data recording chips into tiny packs weighing less than a dime. Then, they strapped the packs on the backs of purple martins and wood thrushes to track their journeys. What they learned made jaws drop throughout the ornithological community: These small birds traveled more than three times faster than anyone had previously thought.

Instead of covering about 90 miles a day, the study revealed that the birds rushed along at the rate of more than 300 miles in 24 hours, an average of 12.5 miles per hour. (Martins migrate in daylight, thrushes at night.) That pace is a much faster one than these birds use in fall, when they slow to 50 to 100 miles a day. For example, one martin equipped with a data backpack left Brazil in April and reached its breeding colony in Pennsylvania a mere 13 days later. That same martin took a full 43 days to return to Brazil in September. That kind of speed is truly remarkable, especially for small birds fueled only by the body fat they pack on each day.

Why are the birds in such a hurry? The males are generally in the forefront of migration. They want to get back early to claim the best breeding territories. So even though flying so fast may leave them exhausted by the time they arrive in northern climates, the early birds are ready to settle in and defend a nesting area against later arrivals.

Tiny backpacks

We can thank new technology for this surprising information about migrating birds. Until now, it's been impossible to track songbirds from one end of their migration route to the other because the monitoring equipment was just too heavy for birds that weigh about 2 ounces.

The new lightweight data devices record sunrise and sunset times as the birds fly. When the data are downloaded, researchers can pinpoint the birds' location each day, revealing how fast they're flying.

Being able to record this information is important for a number of reasons. It indicates that migratory birds are leaving their wintering grounds in Central and South America later than we'd previously thought. Instead of departing in March, it turns out that martins and thrushes are taking off like a shot in April.

Their speed makes having reliable stopover sites along their migration routes all the more important. Birds in a hurry need to feed in a hurry, not spend valuable time hunting for high-energy food. Martins need to find a good supply of large flying insects to keep them going, and thrushes forage on the ground for insect-rich meals. If humans spray a landscape with pesticides, it makes life tougher for these migrants.

"We've always known that once the technology became small enough we could start tracking small birds," said Mark Martell, director of bird conservation for Audubon Minnesota. "And new technology is becoming a tremendous help in adding to our understanding of songbird behavior."

It helps birders have a better understanding about the threats that loss of habitat and climate change pose for birds. And it helps bird-friendly organizations such as Audubon establish conservation measures to combat those threats.

Val Cunningham, a St. Paul nature writer and bird watcher, can be reached at valwrites@comcast.net.