How Is Colorado Flooding Affecting Birds and Other Wildlife?

From his mountain cabin on Middle St. Vrain Creek in Colorado, Steve Bouricius watched as the stream flow swelled from 12 cubic feet per second to more than 1,000 cubic feet per second last week. Standing by the river, which drains out of the foothills north of Boulder, he heard and felt boulders crashing into rocks as they rolled downstream, and saw water eroding soil and uprooting trees. The torrent tore an American dipper nest box, its post sunk in a concrete base in the channel, out of the ground and swept it downstream.

An aquatic songbird, the American dipper catches insects and small fish by diving and swimming in swiftly moving streams (it dips its head under water up to 60 times a minute while foraging, hence its name). It might be the avian species hit hardest by the unprecedented rains and flooding in Colorado.

"During flood events the violent rush of water forces dippers to seek food in side channels and areas flooded beyond the normal stream bank," said Bouricius, who has installed dipper nest boxes in streams throughout the state.

Bouricius saw the birds avoiding the violent waters, spending more time catching flies and foraging for spiders in the streamside foliage. The conditions could hurt juveniles and adults that are molting, he said. In the longer-term, the flooding might render some of their territories uninhabitable.

It'll take time to gauge how dippers and other animals fared during and after storm, but by and large, wildlife seems to have largely escaped the devastation that the extreme weather wreaked on humans.

Six people have been confirmed dead, 201 are missing, and more than 18,000 were forced to leave their homes, according to the Colorado Office of Emergency Management. Sewage treatment plants have overflowed, damaged oil and gas pipelines are leaking, and at least 50 bridges and 200 miles of roads were damaged, the Denver Post reports

Near Denver there was "minimal impact to wildlife at the refuges," said Fish and Wildlife Service press officer Steve Segin. Earlier this week, a spokesperson for the Colorado Division of Parks and Wildlife said that employees were focusing on helping humans and wildlife reports hadn't started coming in. Biologists aren't anticipating big fish kills, but fishermen may see new species in some spots since usually separated waterbodies came into contact.

"For many of the birds in the general region, the heavy rains will have been no more than an inconvenience," said Kenn Kaufman, avian expert and Audubon field editor.

Because this flooding came after the nesting season, there weren't a lot of vulnerable nestlings and fledglings, said Kaufman. And birds can easily fly away from the flash floods that ripped out bridges and swept away homes—so long as the rapidly rising water came during the daytime. As for migrants, many of those that would've stopped along the affected riparian habitats likely shifted to other areas. "Migrants tend to be pretty flexible in their choices of where to stop while migrating," said Kaufman.

Some, however, were trapped. Ted Floyd, editor of Birding, the magazine of the American Birding Association, kept a keen eye out for avian activity in Boulder County. "Practically everything has been grounded," he said on Monday. "There's really no movement of birds to speak of. You go outside and hear Wilson's warblers chittering away in the bushes."

Another migrant was more daring. "Barn swallows are everywhere, flying low to ground," said Floyd. "They're harrassing other birds to try to flush insects. At a marsh by my house I saw them chasing a pied-billed grebe, trying to knock off insects."

While some of the birds might not survive, Floyd doesn't expect that the wet spell will hurt their populations in the long run. "Deforestation in Canada or use of insecticides in North America has a much more harmful effect on barn swallows or Wilson's warblers than a nasty storm in the Rockies," he says.

Most avian mortality comes after a flood. "Birds survive the initial displacement, but then they're at a disadvantage because they're on unfamiliar ground, more vulnerable to predators, perhaps unable to find food readily," said Kaufman.

"We aren't worried that one population is going to blink out," said Alison Holloran, director of science for Audubon Rockies. "We'll certainly lose a few individual birds, of that I am sure. But nature is incredibly resilient."

Many of the areas affected are in the flood plains of the South Platte and the Poudre rivers, but they haven't experienced flooding in decades or more because of dams and other water diversions. Historically, flooding would have created seasonal wetlands and scoured large areas, creating a diversity of habitat in riparian stretches important for migrating waterfowl, shorebirds, and neotropical birds. "This event gives us a chance to reflect on what do we need to do to restore and protect our habitats around rivers," says Holloran.

Recent events exacerbated the flooding, which were triggered by widespread torrential rains. In all, at least five inches of rain pounded down on 17 counties in just a few days. The storm brought Boulder's annual precipitation up to more than 30 inches—more than half falling since September 9—eclipsing the previous record of 29.93 inches set in 1995. Much of the state has been plagued with persistent drought, and the dry conditions, coupled with recent forest fires, made it harder for the ground to absorb the water.

That's something that a new partnership aims to address. In July, the federal government announced a pilot project in the Upper Colorado Headwaters and Big Thompson watershed in Northern Colorado that will reduce the risks of wildfire to the water supply by restoring forest and watershed health.

"Doing nothing brings peril not only to the habitat we have left and the wildlife that depend on it, but to humans as well," says Holloran. "We have to restore and protect our watersheds."

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