Migratory Raptors
By Luke Matthews
Many people are familiar with the fact that millions of waterfowl and shorebirds migrate through the Sacramento Valley every winter; however, there are a number raptor species that also migrate in the winter and often go unnoticed. While Red-tailed Hawks, Red-shouldered Hawks, and American Kestrels dominate the skies throughout the year, there are a variety of hawk and falcon species that visit the Central Valley only in winter, such as Ferruginous Hawk, Rough-legged Hawk, Sharp-shinned Hawk, Merlin, and Prairie Falcon.
Most of these raptors follow the well-known patterns associated with migratory waterfowl of breeding in northern Canada and Alaska then traveling south to winter. In contrast, Ferruginous Hawks travel northeast and breed primarily in the Great Basin and Prairie Pot Hole regions, while Prairie Falcons can be found throughout the state year-round but are only found in the Central Valley during the winter.
These migratory raptors feed on a wide range of prey items. Merlins, a small falcon species, and Sharp-shinned Hawks are both highly skilled aerial predators that almost exclusively eat small birds, however, Merlins are swift enough to occasionally hunt large flying insects and bats. Prairie Falcons typically eat ground squirrels during the breeding season but in California they also frequently target doves, meadowlarks, and other birds. Rough-legged Hawks have a specialized diet of lemmings and voles on their breeding grounds but in winter will hunt a variety of small mammals and birds found in open grasslands, pastures, and farm fields. Of all these winter species, Ferruginous Hawks have the strictest diet, which consists almost exclusively of jackrabbits, cottontails, and ground squirrels.
The next time you are out in rice country to see the millions of migratory waterbirds don’t forget to scan the power lines, fence lines, and nearby trees for some of these amazing migratory raptors. If you are lucky you might witness the speed and acrobatics of a Merlin chasing a flock of shorebirds or the comical site of a Ferruginous Hawk running and hopping through a field in pursuit of a small scurrying mammal.
*Photos courtesy of Ryan Bourbour
Luke Matthews is the Wildlife Programs Manager for the California Rice Commission
