Bird lovers interested in the species' habitat and health throughout Colorado need wait no longer.
The Second Colorado Breeding Bird Atlas, which is only released in 20-year intervals and is considered the most comprehensive overview of changes to bird habitat, land use and other factors within the state - is now available.
Six years in the making, the bird atlas is a long-awaited comparison of birds and their habitats that were documented two decades ago.
Editor Lynn Wickersham said the atlas allows researchers and those interested in birds a snapshot in time of the distribution of breeding birds in Colorado.
"When we can repeat these projects, we can compare our data and maps," she said. "And with that, track whether or not we have some changes in bird population."
Wickersham said it took about 800 volunteers, putting in tens of thousands of hours traversing the state to document nearly 275 species of birds. Many volunteers, she said, ranged from biologists to avid bird-watchers.
While it's impossible to generalize the overall state of birds in Colorado, Wickersham noted a few certain trends.
She said a few species that weren't here 20 years ago, and others that were rarely spotted, have expanded north into Colorado.
She said there could be a variety of factors in play, but "certainly changes in our climate probably contribute to some of those shifts," noting the warmer than average global temperatures.
In other areas that have experienced prolonged drought, especially southeastern Colorado, volunteer surveyors found fewer species than documented the last go around.
Yet, there were some success stories, Wickersham said. Birds that were in decline in the 1980s and 1990s because of pesticide use, such as the peregrine falcon, bald eagle and osprey, rebounded in the state, following the national trend.
"There are a lot of different types of bird-monitoring projects happening," she said. "But as far as what you can learn on a broad scale for the whole state, this is better than anything to give you the most information on current distribution, habitat use and windows of nesting."
Most states produce similar bird atlases, which are considered among the most extensive and influential citizen science projects in the country.
In Colorado, volunteers surveyed the state from 1987 to 1995, publishing the first atlas in 1998, which covered more than 250 species of birds.
The efforts are funded and supported by a number of organizations, including Colorado Parks and Wildlife, U.S. Forest Service, Colorado Bird Atlas Partnership and Fort Lewis College, among others.
Books are available for sale at www.cobreedingbirdatlasii.org/buy.html, Maria's Bookshop and a few selected retailers.