Early Snowmelt Confuses Birds and Bees

Early snowmelt in Colorado's Rocky Mountains (national park shown here) has cued flowers to bloom early, meaning honeybees and hummingbirds miss feeding opportunities. CREDIT: Don Becker, USGS View full size image

SAN FRANCISCO — Early snowmelt in Colorado's Rocky Mountains has cued flowers to bloom early, causing honeybees and hummingbirds to miss feeding opportunities, new research suggests. The animals arrive at their usual feeding times, but are now too late.

The findings, presented Monday (Dec. 3) here at the annual meeting of the American Geophysical Union (AGU), suggest that climate change can disrupt a cascade of animal species in the mountains.

"The timing of winter's end is changing in the Colorado Rocky Mountains," said David Inouye, a researcher at the University of Maryland. "These mismatches in the arrival dates of migratory hummingbirds and the blooming of the flowers where they typically visit are leading to a situation where hummingbirds come after the foods have begun to flower."

Over time, that could make pollinators go hungry, Inouye said.

Since 1973, Inouye and his colleagues have tracked the wildlife and plants in the Rocky Mountains about 9,500 feet (2,900 meters) above sea level. On average, the minimum April temperature has increased 5.5 degrees Fahrenheit (3.1 degrees Celsius). In addition, less snow has fallen, on average, in recent years. [Watch Live: Latest News from 2012 AGU Meeting]

Related climate changes exacerbate the increased temperatures, Inouye said.

For instance, "Dust storms seem to be increasing in frequency," he said. That causes dust to settle on the snow, changing the reflectivity and hastening snowmelt by a week to 10 days earlier than it normally would, he added. All told, snowmelt comes two weeks earlier, on average, than it did in 1975.

But early snowmelt messes up more than just the ski season.

The last snowmelt in the Rocky Mountains sets the clock for the rest of the season, determining when flowers will bloom and when animals will emerge from hibernation, Inouye said in a press conference.

For instance, snowmelt usually alerts plants to begin their growth, which they do about 10 to 20 days later, Heidi Steltzer, a researcher at Colorado State University, said during the press conference.

But when snow melts in April rather than June, flowering plants sprout buds earlier, leaving them susceptible to late-season frosts. For instance, in 2012, there were 0.002 percent fewer blooms emerging from a Rocky mountain flower species compared with 2011.

In the last several years, the early blooming has meant hummingbirds and honeybees arrive late to their usual pollen and nectar sources, the researchers found.

"When the hummingbirds need a lot of nectar to feed their young, that food isn't going to be there."

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