Ridgetop Migration
Photo of Clark’s Nutcracker by Josh Greenfield
The west side of Yolo County is marked by a series of roughly north-to-south oriented ridges, covered mostly in low brush and bare rock. In the last year or so, it turns out that the tops of the ridges are pathways for migrating birds, both songbirds and raptors. The songbirds can be seen traveling in early morning, some near the ground and some higher up. This is a surprise, because most small birds migrate at night. Since nearly all of these sunrise travelers are warblers and other forest birds, I surmise that, as day breaks, they see an inhospitable landscape, and are searching far and wide for patches of trees.
This notion is boosted by the fact that birds are flying in all directions, not just southward. In any event, as the day warms, the flight of small songbirds ends and in autumn, birds of prey appear, often riding thermals. This fall there have been hundreds of Lewis’s woodpeckers as well.
The ridgetops also turn out to serve as migration routes for birds that are typically quite scarce in our county or anywhere in the Sacramento Valley. Amazingly, recent reports collectively note hundreds of evening grosbeaks, dozens of Clark’s nutcrackers, plus Cassin’s finch, Townsend’s solitaire and black swift. All but the swift normally overwinter in California’s Sierras and Cascades. Since these migrants seem to have abandoned the mountains, and have been showing up in lowland southern California, I speculate that some will eventually find their way to the Sacramento Valley, too. So, watch and listen for them.
Photo of Clark’s Nutcracker Flock on the ridgetop by Josh Greenfield
The ridges are mostly inaccessible to the public, but a few spots can be reached by car. These include the top of Reiff Road in the northwest corner of Yolo County and Mt. Vaca on the Solano-Napa County border, near the south end of the line of ridges. It is reached from Mix Canyon.
If you go, be aware that ridgetop bird-finding takes practice. On a recent visit with Reiff Road veterans, I marveled that my companions could identify small songbirds to species, as they flew by. They also spotted approaching birds, from kinglets to eagles, when they were mere specks in the sky – specks that I couldn’t even see, much less get my binoculars on.
For more information, including recent bird lists and driving directions, visit eBird for the region named “Yolo County” or “Solano County” and look for hotspot names “Reiff Rd. Ridgewatch (YOL co.)” or “Mt. Vaca (SOL Co.)” or “Mt. Vaca”.
–Michael Perrone, Conservation Chair