New study offers clues to impact of houses on wildlife
Some species of wildlife actually seem to gravitate toward development, according to a study commissioned by Pitkin County.
On the other hand, many sensitive species avoid development, losing habitat when man moves in.
Preliminary findings by Eric Odell, a master’s degree student in the Department of Fishery and Wildlife Biology at Colorado State University, show more “species richness” in birds occurs near houses. But the same Snowmass-area study indicates that the most sensitive and rare songbirds are found in increasing numbers farther from development.
Odell, who presented his early findings to Pitkin County commissioners Tuesday, said his ongoing work is intended to help county officials determine the effects of increasing development on big game, medium-sized predators and songbirds.
Odell’s study focused only on building activity in mountain shrub vegetation areas, as those areas are the most threatened by development.
His study included Brush Creek, Horse Ranch, Owl Creek and other subdivisions. The occurrence of animals was observed in relation to factors such as house size and development density. Frequency of observation was measured at 30 meters, 180 meters and 330 meters from dwellings.
Odell’s data indicates common birds such as robins, magpies, broad-tailed hummingbirds and mountain bluebirds were most common closer to houses, while rarer species, such as blue-gray gnatcatchers, dusky flycatchers and certain vireo species, as well as the relatively common black-capped chickadee, were most common at 330 meters away from development. Density of housing development in shrublands seems to create the same effect.
“When you increase density you increase species, but you lose the sensitive species,” said Jonathan Lowsky, Pitkin County’s wildlife biologist, who is assisting Odell with the study.
Odell also observed that numbers of deer and elk were affected both by the proximity of houses and density of development. Both animals are more common at greater distances from houses and in less-densely developed areas, he said. Deer are more common in low-density development than elk, which are more likely to shy away from any development, Odell added.
Odell said he originally intended also to investigate the effects of bigger houses, but has discovered that other factors cloud the data.
“Anything that’s concerned with house sizes is going to be confounded by a lot of other issues,” Odell said. Wildlife would shy away from a small house with a dog and a cat more than from a large house that’s visited only rarely by its owner, he said.
At this point, Odell said his most interesting finding is the frequency of common species near houses and the frequency of sensitive species farther away.
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Colorado Gov. Jared Polis has tested positive for the coronavirus. Polis and his partner, Marlon Reis, both have COVID-19 and are asymptomatic, the governor said in a statement Saturday night.