DINOSAUR RIDGE — As traffic flies by on C-470 below, dozens of hawks hurriedly head north, part of the avian spring migration documented by a string of local volunteers armed with binoculars, charts and enthusiasm.
“There, there on the horizon,” HawkWatch volunteer Roger Rouch announces. Then, being a bit more directive — “just above the tree branch, below the lake,” he says — a speck is spotted in the distance against a partly cloudy, hazy sky.
Binoculars are brought to bear, and a jolt of adrenaline hits the birder as the approaching hawk comes into focus.
“They’re on a mission,” Rouch says of the hawks’ determined northern route.
Looking mostly for migrating hawks, Rouch and other volunteers also document other birds.
Hawks are the focus, however, because topography, weather patterns and the birds’ migratory paths make the Front Range of Colorado a hawk highway. Dinosaur Ridge, part of the Dakota Hogback and renowned for its dinosaur fossil beds, is among North America’s premier spots to view hawks.
“Raptors are pretty cool birds,” Rouch said with a smile. “They’re a symbol of freedom and strength.”
On Wednesday, Rouch counted 40 birds, including 29 American kestrels, in about a six-hour span. American kestrels — also known as the sparrow hawk, although the bird is actually a falcon — are the most common falcon in North America.
Rouch also counted four turkey vultures, two Cooper’s hawks and three red-tailed hawks.
Some hawks soared directly above the HawkWatch perch, set atop Dakota Ridge, south of Interstate 70 and north of Alameda Parkway, giving Rouch a bird’s-eye view and allowing for easy, positive identification. Other birds, because of distance, backgrounds, speed and angles, can be more difficult to identify.
The Dakota Ridge HawkWatch volunteer season runs from March 1 through May 7, and volunteers traditionally count between 1,000 to 1,500 birds in the roughly two-month span.
Greg Thomas, a retired Denver-area geologist who volunteered with the program in the early 1990s, hiked to the HawkWatch spot Wednesday with his wife, Stephanie, to view birds and reminisce.
Thomas recalled seeing “kettles of kestrels,” up to 50 at a time, fly by, as well as a hawk carrying a snake in its talons.
Noise from the C-470 highway, nearby Thunder Valley Motocross Park and a law enforcement shooting range drift up to the ridge top. Solterra, a housing development to the south, is pushing toward the hogback.
“It carries a lot more traffic now,” Thomas said of the highway. “Obviously there is a lot more development out here now.”
Formed in the early 1990s, HawkWatch has about 30 volunteers and is run by the Rocky Mountain Bird Observatory, a nonprofit organization headquartered at Barr Lake.
RMBO works with governments and private property owners in an attempt to conserve habitats. HawkWatch has stored data from Dinosaur Ridge dating to 2001, and in the future such data may be used to aid migration studies.
“The big thing with development and bird migration is loss of stopover habitat,” said Jeff Birek, a biologist with RMBO. “Any disturbance could cause them to have avoidance behaviors or activities.”
Migrating birds that no longer have a familiar stopover site expend precious energy scrambling to replace it, Birek said.
“To have habitat, a place where they can go and eat enough food to move onto the next site, it is critically important,” Birek said. “We need to make sure there is connected habitat that birds can move through.”
Kieran Nicholson: 303-954-1822, knicholson@denverpost.com or twitter.com/kierannicholson
