In City Park, on man-made islands in man-made lakes, tall, old trees offer refuge to large colonies of wading birds. The park provides breeding habitat for approximately 100 black-crowned night herons, roughly 300 double-crested cormorants and several species of milk-white egrets, ethereal as angels.
The bird enthusiasts of Denver Field Ornithologists (DFO) hope to focus their 400-plus members’ binoculars on the breeding, nesting and fledging habits of these birds — not just for the joy of birding, but to collect data for their recently launched citizen-science initiative, the Colonial Waterbirds Nesting Project.
The nesting project is one of two citizen-science initiatives at DFO. The second involves data collection that will contribute to the work of Denver Museum of Nature & Science Curator of Ornithology Garth Spellman, who is mapping the occurrence of eastern and Rocky Mountain forms of warbling vireos and white-breasted nuthatches.
“Since we have a quasi-home at the (Denver Museum of Nature & Science), we think it’s worth monitoring the backyard birds here,” said DFO president Chuck Hundertmark.
Hundertmark recently led one of DFO’s field trips to observe City Park’s colony of night herons on the island in Ferril Lake, due east of the boathouse pavilion. Dozens of the sharp-beaked, ruby-eyed birds stoically sat on nests, incubating eggs. Some cruised in and out with nest-building sticks. Others engaged in territorial behavior or courtship dances.
On the island in nearby Duck Lake, approximately 200 nests crowded trees, and cormorants raised a cacophony. Hundertmark, using his spotting scope, pointed out the double crests that resemble feathery horns, visible only during breeding season.
Cormorants have nested in City Park for 80 or 90 years, said DFO member Pat O’Driscoll in an email. “Somebody once relocated half a dozen fledglings there from the big colony that still exists at Barr Lake,” O’Driscoll said.
The DFO database will chart dynamics of the waterbird colonies and the condition of the sites.
“If the sites begin to fail, we want to follow the birds, faithful returnees year after year, as they relocate to other sites or even start new colonies elsewhere. We also want to document the timing of the nest cycle to see if there is a response to climate change,” O’Driscoll said.
The birding club is recruiting citizen-scientists to help compile data on colonial waterbirds in Washington Park, Belmar Park in Lakewood, the Wheat Ridge Greenbelt, as well as City Park.“In the case of City Park’s Duck Lake, it’s a minor miracle that its tall trees — nearly dead now, possibly from decades of cormorant guano — are still standing under hundreds of three-foot birds and their big nests of sticks,” O’Driscoll said.DFO and other citizen-scientists can use an app called eBird to compile field notes for the waterbird study, Hundertmark said. “There’s no fee or registration, and you don’t need to belong to DFO to help. This is how DFO can harness the collective power of observation and eBird for vital citizen-science. It’s fun and interesting and will enhance knowledge and appreciation of birds.”When people share lists on eBird, “they’ll just type in ‘DFO waterbirds,’ ” O’Driscoll said. At the end of the season, DFO will compile a report on the first year’s worth of data. “We’re piggybacking on the ability of using eBird’s way of compiling and organizing data. It’s just a lot easier than if we sent people out with clipboards.”
Birds of a feather
Birders possess keen powers of observation and curiosity inspired by the natural world. A new DFO board member and the newsletter editor, Sharon Tinianow said, “You’re out in nature. People who know birds usually know wildflowers and trees, mammals, reptiles.”
Tinianow’s favorite birds are chickadees. “They’re acrobatic little critters, such charming birds.”
At her Denver home, Tinianow maintains three birdfeeders and a suet hanger. She noted that birding is an audio-visual activity. “Birding by ear, you don’t have to spot the bird to identify it.”
On the field trip, Hundertmark heard a chipping sparrow, traced the song to a tree and deftly centered the bird in his scope. Birders also heard the avian operas of house finches, calls of northern flickers, trills of red-winged blackbirds.
Hundertmark has almost 800 species on his Life List.
Birds of a feather, as we know, flock together. And birds bring humans together, too. The DFO flock includes 470 members. And wherever birders congregate, other people gather like hummingbirds to nectar. With their command of flight and mysterious migration abilities, birds captivate the imagination.
“Every time I’m out birding, somebody comes up to ask a bird question,” Hundertmark said.
As if on cue, a woman walking her dog stopped to inquire about the large white birds. She mentioned the bald eagle she saw. Later, a rangy man wearing a black cowboy hat wandered over to inquire about the cormorants.
Isaac Ho, a retired chemical engineer and DFO member, focuses more on photography than his Life List. For Ho, bird-watching was a family interest shared with his wife and children.
“By watching birds, you gain a lot of interesting experiences. If you have an awareness of behavior, you can realize there is a lot of humanity in wildlife,” he said. “Nature deserves our respect.”
Ho’s favorite birds are raptors. “I like to photograph them in flight or action,” he said. “Springtime is a perfect time to watch birds.”
The City Park field trip also yielded sightings of mallard and blue-winged teal ducks, violet-green swallows and barn swallows, ring-billed gulls and black-billed magpies, American robins and Canada geese—including goslings yellow and fuzzy as spring pollen.
For fledgling birders, Hundertmark suggested picking up a field guide.
“Get a good bird book and learn how to use it,” he said.