Report: Habitat loss hurting Colorado birds | SummitDaily.com

Report: Habitat loss hurting Colorado birds

BOB BERWYN
summit daily news
Special to the Daily/Colorado Division of WildlifeMountain bluebirds are not considered threatened or endangered, and grassroots efforts by citizens have helped bolster populations of the lovely birds locally. But habitat fragmentation and climate change are affecting habitat for many other types of birds in Colorado.
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SUMMIT COUNTY ” Habitat loss and climate change are putting pressure on some of Colorado’s native and migratory birds, including the Rosy Finches of Summit County’s alpine zone, as well as sage-dependent Brewer’s sparrows, Warbling Vireos and many other species.

Some of the concerns about avian species in Colorado and the rest of the country were outlined last week in a comprehensive national report compiled by the American Bird Conservancy.

Secretary of the Interior Ken Salazar helped publicize the report by appearing at a press conference and highlighting some of the key findings in the document. The report, including video materials and a recording of Salazar’s press conference, are online at http://www.stateofthebirds.org.

“It’s a very, very important document … because it’s scientifically grounded,” Salazar said, outlining some of the impacts to bird populations associated with population growth, global warming and climate change and water quality issues.

Salazar pointed out that the conservation group worked closely with the U.S. Fish and Wildlife Service to compile the data for the report.

“There is a way we can address these problems in a systemic way,” Salazar said. Partnerships with state agencies and private landowners are crucial to maintaining and improving habitat for birds, he said.

“Birds are amazing creatures. Unlike us, they don’t sit around and debate environmental issues. They just react. And if we want to understand what’s happening to our natural world, we need to pay attention to what they’re telling us,” said John Flicker, president of the Audubon Society.

In Colorado, the greatest threat to the state’s birds also stems from loss of habitat, said Dave Klute, bird conservation coordinator for the Colorado Division of Wildlife. Some of the habitat loss is due to fragmentation from suburban development and energy development, but other factors, including climate change and the mountain pine beetle epidemic, may be the biggest concern for High Country birds, Klute said.

When it comes to climate change, there’s not much of a buffer for high-elevation birds.

There’s not a lot of habitat at high elevations. They depend in those islands … if they’re gone, there’s no place for them to go,” Klute said.

And while there appears to be a vast quantity of sage shrublands, oil and gas drilling has had a significant impact on bird habitat at lower elevations across the Western Slope.

“You may see what looks like the same kind of habitat out there, but it’s not the same quality,” Klute said. The roads and overall disturbances have resulted in increased predator densities and lower reproductive rates for birds dependent on that habitat, including sage grouse and Brewer’s Sparrows.

“Habitat fragmentation is disrupting life cycles around the region,” said Dan Casey, the regional coordinator for the bird conservancy group. “One of the real big issues is the management of sage areas,” Casey said, adding that fire-supression and over-grazing are other factors in addition to energy development.

Riparian habitat, close to streams and lakes, is critically important to many bird species. Those areas are also often desired areas for new development, Casey said, explaining that many Western bird species depend on those riparian areas for food and nesting sites.

Some of the same trends seen at the state and regional level are reinforced by ongoing research at the Cucumber Gulch wetlands in Breckenridge.

Christi Carello, a biology professor at Metropolitan State College in Denver, has been monitoring wildlife in the gulch for several years on behalf of the town. A number of factors have contributed to habitat fragmentation in and around the wetlands, Carello said.

The resulting “edge effect” has led to a proliferation of Brown-headed cowbirds, a nest parasite that displaces other species by putting its eggs into the nests of other birds.

“They love the forest edge,” Carello said of the cowbirds.

Carello said Warbling Vireos have been hit especially hard by the cowbird invasion in the past few years.

Some species have bounced back. Carello said she initially tracked a worrisome decline in the number of violet-green swallows, but that their numbers have recently returned to earlier levels.

She explained that not all bird population declines can necessarily be attributed to local impacts.

“You have to look at what’s going on in the neo-tropics,” she said, referring to the tropic and sub-tropic parts of South America where many of the migrant birds over-winter. As well, the “re-fueling stations” along the way, where the birds stop along their migratory path, are also seeing impacts from a variety of factors.

That points to the fact that the decline in bird populations is a global problem.

“The biggest environmental issue on this planet right now is the loss of biodiversity,” Carello said. Losing individual species can end up having a cascading effect on larger eco-systems, as a particular biological function is lost.

For example, some birds eat huge amounts of insects, and if that species is lost, it can lead to increasing numbers of undesirable bugs.

“We need to be careful not to lose the rich biodiversity we have associated with this rich habitat in Cucumber Gulch,” Carello concluded.

Bob Berwyn can be reached at (970) 331-5996, or at bberwyn@summitdaily.com.


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