At the base of Waterton Canyon, southwest of Denver, groves of cottonwood trees and a rich understory of shrubs and junipers line the South Platte River. I often visit this area, especially during the warmer months, since it attracts a wide variety of Front Range songbirds; in addition, dippers may be found in the river and golden eagles often soar along the edge of the foothills.
This morning, I was surprised to encounter an eastern phoebe, a species that I have not previously observed in Colorado. Back in Missouri (and across the eastern and central U.S.), this bird is common and is among the earliest summer residents to arrive in the spring. While its cousin, Say's phoebe is a common summer resident along the base of the foothills (favoring open shrublands), only sporadic sightings of eastern phoebes have been reported in recent years.
Like northern cardinals and white-throated sparrows, eastern phoebes seem to be expanding their range into Colorado. In such cases, human alteration of natural habitat generally plays a role and eastern phoebes, like cliff and barn swallows, often nest beneath bridges and the eaves of barns, cabins or sheds. Clearly, the Front Range urban corridor (especially along the South Platte River and its major tributaries) has proved to be appealing to this hardy insectivore.
