Fall Flight (Northwest and Northern California)
Wind plays a major role in bird migration. In the fall, wind circulation patterns around highs and lows impact the movement of migratory birds. The ideal time for flying often occurs the day after a cold front passes – north winds, dropping temperatures, rising air pressure and clearing skies are good migration conditions.
Soaring birds like hawks, osprey and eagles depend heavily on wind for migration. According to scientists, the second day after a cold front passage is the best time to observe hawk migration in the fall, when there are northwest to west winds that produce updrafts. Soaring birds glide along updrafts, which conserves energy. If soaring birds flapped their wings constantly during migration, they would exhaust their fat stores long before reaching their destination.
Viewer Tip: In the Northwestern United States and Northern California, you may notice hawks and waterfowl drop into your yard to rest and find food at this time of year. You can encourage both migrant and resident birds, like evening grosbeaks and cedar waxwings, to visit your yard by offering different types of foods – seed, nuts, berries or suet – and different kinds of feeders.
If you enjoy watching the birds in your yard, consider sharing your observations. Join the Cornell Lab of Ornithology’s Project Feeder Watch to help scientists track the movement and distribution of birds. It’s as simple as periodically counting the bird species you see in your yard from November through April. Visit http://www.birds.cornell.edu/pfw to sign up for 2010-2011 season.
(Sources: Lincoln, Frederick C., Steven R. Peterson, and John L. Zimmerman. 1998. Migration of birds. U.S. Department of the Interior, U.S. Fish and Wildlife Service, Washington, D.C. Circular 16. Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/othrdata/migratio/migratio.htm; eNature.com, “Regional Birder,” http://www.enature.com/birding/index.asp; National Audubon Society. “Audubon At Home: An Invitation to a Healthy Yard.” http://www.audubonathome.org/yard/index.html)