In 2015, I became a “patch birder,” focusing my outings near my central Denver apartment. Usually, this meant visiting Cheesman Park and Denver Botanic Gardens next door. In part, I did this to spend less time in my car and more time in the field. But I also did so because at that time, Cheesman and the Gardens were “underbirded,” a term meant to describe locations with relatively few checklists on eBird.
At the start of 2015, fewer than 90 species had been reported to eBird from the two locations. This gave me the opportunity for one of the undisputed thrills of birding: To “discover” species in the middle of an urban center where many had yet to be recorded — in this case, central Denver.
So that spring, I visited both locations regularly — and I was rewarded with “discovery” after discovery. In April and May alone, I added 16 species to the joint Gardens/Cheesman hotspot list on eBird. In fall and winter, I added another 11. With fresh attention to this rather overlooked location, more other birders joined in. By the end of 2015, the hotspot list had grown by one-third, to more than 120 birds. In the years since, birders have boosted the eBird checklist to 150 species.
Among these additions were many “good” birds for urban Denver: Red Crossbill, Common Poorwill, Brown Thrasher and Sage Thrasher. Philadelphia Vireo, a rarity, visited in September 2015, giving good looks to me and Chris Rurik, who identified it. In May 2017, another local birder found Virginia’s and Black-throated Gray warblers, and in April 2018, both Long-eared Owl and Loggerhead Shrike on the same day! Suddenly, a tepid, back-burner destination on Denver’s eBird map was hot.
I learned a couple of valuable lessons birding Cheesman and the Gardens in 2015: eBird is an imperfect guide to the reality of birds in our region, and there is a long history of birding in Colorado still awaiting discovery.
So many of us rely on eBird to lead us to lifers, rarities and “good” birds — and yet, here in central Denver, hidden from eBirders for years, were at least 150 common, uncommon, and rare species.
Digging into the history can help us understand how our present-day finds are often encounters with birds that have long visited our state and its people . . . people like William H. Bergtold, whose century-old footsteps I would soon find myself retracing in Cheesman Park.
Born in 1865, Bergtold lived and birded in central Denver more than a century ago. He came to Colorado, as I had, from the Northeast; we both grew up in upstate New York. For a time, he even worked for my current employer, the University of Denver, teaching in DU’s medical school at the end of the 19th century.
An 1899 note in the journal Science reported that Bergtold was the first president of what may have been the first bird-related organization in the state, the Colorado Ornithological Association. Over the first three decades of the 20th century, he published numerous reports, articles, and books on Colorado’s birds. Those writings led me to Bergtold. Yes, while looking for Cheesman’s birds, I found one of the park’s first birders.
Bergtold wrote one of the state’s first books for birding, A Guide to Colorado’s Birds. Through his articles, he did something further — he told stories of the times. In a 1921 article about the “English Sparrow” (now House Sparrow) and the rise of motor vehicles, Bergtold speculated that the transition to automobiles from horses in urban centers might reduce the population of a despised non-native bird. Not only would fewer horses mean fewer horse droppings (road apples?!) for starving sparrows to comb for morsels, it would “probably also (make) the species’ street life so hazardous and fatal as to drive it largely out of the business area” of downtown Denver.
Many of Bergtold’s reports focused on birds in Denver and surrounding cities. He publicized other birders’ accounts of uncommon and rare birds. Noteworthy was a pair of Northern Cardinals that apparently nested in Littleton for several years. Reading Bergtold’s reports today, I can’t help but marvel at the city of a century ago — its natural and human-made landscapes, the birds that populated them, and the people who watched those birds.
“The Birds of Denver: An Annotated List,” Bergtold’s 1917 essay in The Wilson Bulletin, is riveting for what it tells us about bird diversity in Cheesman Park and around the city. Some species we take for granted today were far less numerous in Bergtold’s time — and others that were common here in his day are scarcer now.
Writing about the American Crow, Bergtold noticed one “flying over Eleventh Avenue and Corona Street, December 7, 1913.” Another Crow was “seen in Cheesman Park, May 1, 1917.” Where he once noticed a single bird, I have watched hundreds of crows fill the park, which seems to be a staging ground for overnight roosting in late autumn and winter. Spotted Towhee, a rather ubiquitous backyard sparrow these days, was even scarcer. On Jan. 1, 1913, Bergtold wrote, “One detected in Montclair,” a Denver neighborhood 3 miles east of Cheesman. Black-capped Chickadees (in those days called Long-tailed Chickadees) hadn’t even begun nesting in Denver but instead were “regular winter visitors,” he said.
His reports also reflect what the city has lost to human alteration of once-natural landscapes. Pine Siskin was once a common spring nester in Denver, the bulk arriving “early in March, and many linger till June . . . probably going to higher altitudes to nest a second time.” Bergtold tells us Black-headed Grosbeak and Bullock’s Oriole were common breeders throughout the city a century ago. Although less common, Lazuli Bunting and Northern Mockingbird both were regular summer breeders in the city, too. Although Colorado Breeding Bird Atlas II lists them all as breeders in Denver County, none seems as common in the city as Bergtold suggests they once were.
One bird I’m particularly fond of roosts in the midst of these losses and gains. According to Bergtold, Common Poorwill was an infrequent migrant through Cheesman Park — and it still is today.
Having stalked through Cheesman a century after Bergtold, I like to think there was a connection between the poorwills we both encountered. I imagine that through decades and generations of humans and birds — then, now, and after us — the poorwills come and go, only occasionally resting in places like Cheesman where birders decide to look.
To read more about Bergtold, consider these articles:
- “The English Sparrow (Passer domesticus) and the Motor Vehicle” W.H. Bergtold in The Auk (1921), at https://www.jstor.org/stable/4073887
- “The Birds of Denver: An Annotated List” Bergtold, in The Wilson Bulletin (1917), available at https://www.jstor.org/stable/4154774
- “In Memoriam: William Harry Bergtold,” Albert Kenrick Fisher, in The Auk (1937), at https://sora.unm.edu/sites/default/files/journals/auk/v054n01/p0001-p0011.pdf
This essay first appeared in the October 2022 newsletter of Denver Field Ornithologists, The Lark Bunting.
Featured photo of Cheesman Park in Denver by flickr user Ken Lund.