ACES Birding by Habitat: Airport Open Space 5/16/2024

This special field trip is a highlight every spring when Pitkin County Airport is closed for maintenance and the adjacent Sky Mountain Park opens for the season. We work with the airport and open space program for permission to enter the portion of our route that is normally closed to public access. With 45 species on today’s list, this is one of the most productive birding trips ACES does, owing to the varied habitats and spring migration timing. Some of the species we saw today, such as Lincoln’s, Fox, and White-crowned sparrows, Yellow-rumped warblers, and Cassin’s finches will be moving to their higher elevation breeding ranges soon. We began our loop hike at the airport facility on Owl Creek Road and walked into the Airport Open Space. We enjoyed great bird activity as we walked past wetlands, sagebrush meadows, and mountain shrublands, including a MacGillivray’s warbler and a flock of Brewer’s blackbirds.

Passing through the historic ranch compound with its cabin, house, and outbuildings ruins, we saw House wrens, a Bullock’s oriole, and many American robins. We discussed the history of the Stapleton’s ranch, originating in 1881, through its acquisition by the County Open Space program in 1993. Stands of large cottonwoods and aspen groves edged open grassy meadows where Chipping sparrows and White-crowned sparrows fed on the ground and Ruby-crowned kinglets sang from the canopy. Yellow warblers chased each other in territorial disputes, while a Red-tailed hawk sailed overhead.

Walking up the Radar Road, we spotted a pair of Black-capped chickadees excavating a nesting cavity in a rotten knothole of an aspen tree. Both members of the pair took turns going into the cavity and backing out to toss tiny wood chips to the ground. It was magical to witness this activity and to confirm that Black-capped chickadees can indeed excavate a home if the wood is soft enough. At our high point on the Radar Road, we enjoyed sweeping views of the upper valley and surrounding peaks, noting geological features such as glacial outwash plains, moraines, and shale deposited under an ancient inland sea. We saw the local elk herd on pastureland in the Owl Creek area and discussed their migration and winter range activities that take place on the open space land where we stood. Towhees, Orange-crowned warblers, bluebirds, and Scrub jays sang and moved about in the dry shrublands on the shale flanks of Sky Mountain Park. As we walked back down to cross Owl Creek and conclude our trip, we watched swallows foraging over the aspen groves and sapsuckers within the forest. Everyone contributed excellent sightings and topics of conversation for this rich learning experience. Join us next week for Morning Birding at Rock Bottom Ranch!