Yellowstone Study Identifies Local
"Hot Spots" for Songbirds
by Annette Trinity-Stevens
Although Yellowstone National Park is associated with bears and elk, it may be the birds who best
signal whether humans are changing the surrounding ecosystem, a study at MSU has found.
Songbirds generally are less common in higher elevations within the protective borders of the park
than they are at lower elevations on or near the private lands outside the park, according to the
study led by MSU ecologists Andy Hansen and Jay Rotella.
"The big message is that both the density of birds and the intensity of human land use vary with
elevation and habitat type," said Rotella, an avian ecologist and head of the MSU Ecology Department.
Few songbirds were found up high where soils are poor and winters are long. Instead, "hot spots"
of biodiversity exist down along river beds and riparian zones surrounded by willow, aspen and
While that sounds good for the birds, these low-lying hot spots tend to occur on or near private
lands. Rural residential development and other land uses can reduce nesting success in these
hot spots. Bird reproduction in these areas can be too low to outweigh the number of deaths,
especially for species like the yellow warbler that are vulnerable to nest raiders.
"Birds still seem to want to come into these cottonwood forests in large numbers, despite the
fact that most don't have good breeding success," Rotella said. "That's sort of a shock in a
way and maybe not as big of a surprise in another way."
Birds likely choose breeding sites based on vegetation characteristics. This probably worked
well over evolutionary time. But nesting success now seems also to relate to the density of
homes in the area, with impacts reaching as far as three to five miles of home sites, Rotella
said. That's because predators, such as magpies, cow birds, skunks and raccoons, increase with
agricultural and residential land uses.
The five-year songbird study, now complete, was just one part of a broad look at how human
populations around Yellowstone affect the entire 60,000-square-mile mosaic of National Park
Service, Forest Service and private lands known as the Greater Yellowstone Ecosystem. The study
also asked, in turn, how the ecosystem affects human behavior, such as the desire to live near
"We found that many new residents are attracted by the nature and beauty of Yellowstone,"
Hansen said. "However, we may be harming wildlife by where we place our homes. The challenge
around Yellowstone is to manage future growth to maintain the qualities of the ecosystem that
we value so highly."
Funded by NASA and a variety of other federal and state agencies, the songbird project called
upon satellite images, geographic information systems and the auditory skills of a dozen or so
bleary-eyed college students. The students rose well before dawn each summer day to tally birds
and document vegetation at field sites in Bozeman, West Yellowstone and Island Park, Idaho.
"After six weeks or so of surveying birds, our crews tend to be a little grumpy, a little
sleep-deprived," Hansen said.
Nevertheless, said crew leader Matt Kraska, each day offered something new.
"Every day I saw something I'd never seen before, even though I'd been there maybe 80 times,"
Kraska said. "That was the most wonderful thing about it."
Hansen said the next step should be to see if the results for songbirds apply to other species
such as bears, ungulates and native trout that may be at-risk from rural residential development.
"By simply letting folks know the importance of that aspen grove on their land or those riparian
cottonwoods, a lot of landowners may be very interested in maintaining those habitats," Hansen
The team also plans a two-year study of biodiversity hot spots in an area stretching from the
eastern side of the Northern Rockies to the Oregon and Washington coasts. That project would be
funded by the National Council on Air and Stream Improvement, a consortium of timber companies.
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