Early bird may find there's little to eat

The ruby-throated hummingbird has been migrating weeks earlier to North America.
The ruby-throated hummingbird has been migrating weeks earlier to North America. (TERRY SOHL / Associated Press, File)
Posted: February 18, 2013

CHARLESTON, S.C. - Ruby-throated hummingbirds are migrating to North America weeks earlier than in decades past, and research indicates higher temperatures in their winter habitat may be the reason.

Researchers say the early arrival could mean less food at nesting time for the tiny birds that feed on insect pests, help pollinate flowers, and are popular with birdwatchers.

"Hummingbirds are charismatic, and they do things that fascinate us," said Ron Johnson, a scientist at Clemson University and one of the study's authors. "They fly backward, and they hover, and they will come to feeders at homes so people can easily see them."

Johnson and colleagues from Clemson; Taylor University in Upland, Ind.; and the University of Nebraska last month published an article on the migration of the hummingbirds in The Auk, the Journal of the American Ornithologists Union.

The birds, which weigh little more than a nickel, fly hundreds of miles from their wintering grounds in Central America to North America. The research compared data on their first arrival times from 1890 to 1969 with arrival times during the last 15 years or so. It found that the birds are arriving in North America 12 to 18 days earlie.

Jason Courtier of Taylor University said the data are based on government surveys from about 3,000 naturalists around the country who recorded the first spring arrival time of bird species over the decades.

Scientists say the earlier arrivals could be problematic for hummingbirds, of which there are an estimated seven million.

"It's good to show up at the nesting grounds at a good time when you can set up a territory and build your nest and when the young come along there will be a lot of food available," Johnson said.

Since ecological systems work differently, he said, the flowers and insects of the hummingbirds' diet might not be available when they arrive earlier.

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