By Jim Gain
Learn 100 Common Valley Birds is a photo blog series highlighting the 100 most common Valley bird species.
Post #21 in the Learn 100 Common Valley Birds series. (Species 33/100)
Swainson’s Hawk #33
Swainson’s Hawk (Buteo swainsoni) is a migratory raptor that breeds in North America and winters in South America. In the Central Valley of California, Swainson’s Hawks typically arrive in mid-March and depart by the end of September. During the breeding season, they prefer to nest in tall trees and hunt for prey in open fields and grasslands.
Swainson’s Hawks have three distinctive plumage variations (called morphs); pale morphs, intermediate morphs and dark. Pale morph birds show a dark breast-band, or “bib,” between a lighter belly and throat.
Intermediate morphs show a pale forehead at close range and an evenly colored backside.
The darkest morph adult Swainson’s Hawks lack a sharp contrast between wing-linings and flight-feathers, and their entire breast and belly can be nearly uniform dark brown.
In the Central Valley of California, Swainson’s Hawks primarily feed on small mammals such as voles, gophers, and ground squirrels. During the non-breeding season, they also consume insects, reptiles, and birds. Swainson’s Hawks are known for their soaring flight, often flying at high altitudes in search of prey or during migration. They also perform aerial acrobatics during courtship displays, where they spiral and dive in a display of agility and strength.
In recent years, Swainson’s Hawk populations have faced threats from habitat loss, pesticide exposure, and electrocution from power lines. However, conservation efforts have been successful in protecting breeding and wintering habitats, reducing pesticide use, and installing “raptor-safe” power poles. As a result, Swainson’s Hawk populations have been stable or increasing in some areas of their range.
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