Yellow-headed blackbirds are recurrent visitors to San Bernardino County, primarily in the coolest months of the year. Though they are occasionally seen throughout the county’s interior, they are most likely to show up in areas along the Colorado River.
A medium-sized blackbird, the yellow-headed blackbird is known by its scientific name Xanthocephalus xanthocephalus, and is the only member of the genus Xanthocephalus.
The adult male is mainly black with a yellow head and breast; they have a white wing patch sometimes only visible in flight. The adult female is mainly brown with a dull yellow throat and breast. Both genders resemble the respective genders of the smaller yellow-hooded blackbird of South America. Adults have a pointed bill.
The breeding habitat of the yellow-headed blackbird is cattail (Typha species) marshes in North America, mainly west of the Great Lakes. They nest in colonies, often sharing their habitat closely with the red-winged blackbird (Agelaius phoeniceus). The nest is built by the female on a spot selected by the male, and consists of a bulky, deep cup woven of aquatic plants, lined with dry grass or with fine, dry marsh plants, and lashed to other marsh vegetation.
During the breeding and nesting season the males are very territorial and spend much of their time perched on reed stalks, displaying themselves, and chasing off intruders and defending the nest against rivals by singing. One male may have as many as five mates.
Females generally lay four pale gray to pale green eggs, blotched and dotted with brown or gray spots, sometimes as few as three and occasionally five. Incubation is done by the female alone, for eleven to thirteen days. Both parents feed nestlings. The young leave the nest after about nine to twelve days, but remain among dense marsh plants until they are ready to fly, about three weeks after hatching. Couples have one brood per year, possibly two.
These birds migrate in the winter to the southwestern United States and Mexico. They often migrate in huge flocks with other species of birds. The only regions of the United States where these blackbirds are permanent residents are the San Joaquin Valley and the Lower Colorado River Valley of Arizona and California.
In extremely rare cases, these birds have been seen in Western Europe, though it is not known for certain that they have flown that far or were escapees from human activity.
These birds forage in marshes, in fields or on the ground; they sometimes catch insects in flight. They mainly eat seeds and insects, feeding heavily on insects in summer, especially beetles, caterpillars, and grasshoppers, also ants, wasps, and others, plus a few spiders and snails. Young are fed mostly insects. Probably two-thirds of their diet consists of seeds, including grass and weed seeds plus waste grain. They may follow farm machinery in fields to feed on insects and grubs turned up by plows. Outside the nesting period, they will feed in flocks, often with related species.
Impressive to see, but not to hear, the yellow-headed blackbird’s song resembles the grating of a rusty hinge, a hoarse, harsh scraping. When not nesting, they gather in flocks in open fields, often with other blackbirds. At some favored points in the southwest in winter, they may be seen in flocks of thousands.
From Wikipedia and the Audubon Field Guide.