Each spring and fall season brings avian surprises to Chico Basin Ranch’s riparian areas; locally known to birders as a perfect migrant trap. Spring often brings an amazing variety of colorful warblers, blown off course in their hormone-driven efforts to get to the best breeding grounds where males will sing incessantly to attract a mate. Fall, however, offers a different type of migration pattern where local weather conditions may cause seasonal variations in bird species and numbers seen. For example, sometimes mountain cone crops fail necessitating a mass exodus by birds and their constant search for winter food. Riparian areas on Chico often provide, at least temporarily, food for these wandering mountain birds. This September, for example, a good variety of Colorado’s mountain breeding birds has spent one or more days on Chico and some individuals may spend the winter here. Some examples include a good number of Mountain Chickadees (photo), a few Cassin’s Finches, a Red Crossbill, large numbers of Pine Siskins, a good mix of Red-breasted and White-breasted nuthatches and one Pygmy Nuthatch, the latter species rarely recorded on the Chico. Other mountain birds of note observed on the Chico in recent weeks include an Evening Grosbeak, mountain races of both Hairy and Downy woodpeckers (photo), two young Cedar Waxwings, a beautiful Brown Creeper (photo), good numbers of Western Tanagers, a few Red-naped Sapsuckers, a high number of the small Ruby-crowned Kinglet (photo) and their tiny relative, Golden-crowned Kinglet (photo), plus many Hermit and Swainson’s thrushes, both species on their way south to winter in northern South America.
Most of these birds are only passing through but some of the Townsend’s Solitaires (photo) will stay to feast on the persistent Russian olive fruits. Each winter many individuals of the Gambel’s race of White-crowned Sparrow will spend the winter at Chico searching for the abundant seeds resulting in a boom cycle for various prairie flowering plants. Joining them will be the Colorado mountain race of Dark-eyed Junco called Gray-headed Junco foraging alongside other northwestern subspecies of this familiar junco. Each fall’s observations are different as are each day’s arrivals, creating for birders the ultimate spot for an avian treasure hunt. Having visited Chico over and over again during the past 12 years, each visit is still a thrill and I still encounter new species here.