Wednesday, April 4, 2012

Birds arrive on schedule

Migrants return to the valley

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By KATHERINE WUTZ
Express Staff Writer

The sounds of chirping and singing are coming back to the Wood River Valley, as migratory birds start returning to the region.

The American Bird Conservancy reported last month that many avid bird-watchers in the nation are noticing earlier arrivals for migratory birds—sometimes by as much as three weeks, according to organization spokesman Jason Berry.

"We don't know if the warm weather we've been seeing the past few months is related to climate change or is nothing more than one of the many weather anomalies that have occurred many times over thousands of years," Berry said in a press release.

However, local schoolteacher and birdwatcher Brian Sturges said that he hasn't seen any such anomaly—or evidence of climate change—in the migratory patterns of birds in central Idaho.

"Migration is such a complex issue that it can be difficult to gauge," he said, adding, "The arrival dates for birds here are pretty consistent."

Whether or not they are early, birds are starting to arrive. The first of the migratory birds arrived around Presidents Day weekend in February, and owls started nesting at the end of that month.

"People start to notice red-winged blackbirds and robins, returning hawks and things like that," Sturges said. "Around late February, we start to get some robins showing up in numbers [rather than isolated birds]."

Robins have been evident throughout the valley for almost a month, and Sturges said it's almost time to look for some of the neotropical migrants, like hummingbirds.

According to a brochure by the Idaho Department of Fish and Game, these birds migrate south to Mexico, the Caribbean islands and Central and South America in the autumn, returning every spring to breed in more moderate climates. The department says 150 Idaho bird species make this journey every year.

Sturges says he hangs up his hummingbird feeder every year on April 15, but has never seen one of the tiny birds before April 23. Currently, he said, birdwatchers are more likely to see bluebirds and finches coming back before hummingbirds and warblers. Hawks also are returning, he said, and by the third week in April, shorebirds should begin to arrive on the Camas Prairie.

Bird migration, according to Fish and Game and Sturges, is more likely regulated by the length of a day than by warm weather up north.

As days on the north side of the equator lengthen and the days south of the equator shorten, birds head north looking for more time to hunt down food.

"A bird that starts in Mexico has no idea what the weather is like in Idaho," Sturges said. However, Sturges said, birds may move farther, faster, if severe weather up north does not stop them—that might be the reason for early arrival times in other areas, he said.

"Most people think they start one day and they go and they are done," he said. "Sometimes what will happen is that the birds will come into the valley and there will be a weather event and they will stay here for a few weeks before they go into the mountains."

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