Hummingbird, songbird migration begins

Male hummingbirds are starting their migration to Central America. Warblers and thrushes won't be far behind. Soon, nighthawks will be swooping over soccer fields and open meadows, sucking down insects on their flight south.

It's happening, whether we want to admit it or not. Summer is on the wane. And the birds are among the first to respond. The migration is on.

"We're just at the start of it. All month, it will be building," said birder Laura Erickson, author of several books on birding and host of public radio's "For the Birds" program.

Here's what's happening:

Hummingbirds moving

If you're seeing more hummingbirds at your feeders, don't be surprised. Males already have begun their migration, Erickson said, leaving females and this year's young behind.

"Females have to replenish their bodies after they're done raising young," Erickson said. "Then they light out for the territory. ... As more flowers dry up, there's less natural food. If the adults clear out, it leaves more for the babies. But they never leave until their bodies have the right fat content."

How do the young know where to go when it's time?

"It's inexplicable," Erickson said, "but they have a little map in their brain. Many birds start recognizing at a young age where the stars and sun are in the sky."

When hummingbirds reach the Gulf of Mexico they face a serious challenge.

"They stop and really pig out," Erickson said. "Then they make the most incredible flight. After their weight is up and it looks like a good day, they head straight out over the water and fly and fly and fly."

They have to cover 600 miles nonstop - and, no, they do not ride on the backs of geese. They start about midmorning, Erickson said, and reach the Yucatan on the far side by midday the next day.

She reminds people who feed hummingbirds that there's no need to add red food coloring to the sugar-water. In fact, she said, the food coloring can be harmful to hummingbirds.

Thrushes and robins

You may recognize lots of other birds around your home, too, she said. Warbler young have fledged and are moving around. People might notice them at bird baths in yards, Erickson said.

As more berries ripen, thrushes (veery thrushes, Swainson's thrushes, hermit thrushes) will be moving through.

Robins are mostly finished nesting. (Erickson's pair had three batches of young this year.)

The nighthawk migration should begin this week, Erickson said.

"Sometimes in midafternoons, people out in the countryside will see them gathering over fields, gliding and diving for insects.

"We used to watch them over soccer fields when the kids were playing," Erickson said. "They swarm as they catch bugs, and as evening progresses, they get higher and higher. They're pretty much going due east to west."

In some years, they pass over in 10s of thousands, she said. They're flying all the way to South America.

Come September, the raptor migration will begin in earnest, with the peak of the broad-winged hawk due to occur in the middle of the month.

"Right now, there are more birds in North America than all year," Erickson said. "This is the peak, with all the baby birds. In your yard, there are way more birds than you might expect."