|
Yellow-Headed Blackbird
The yellow-headed blackbirds (Xanthocephalus xanthocephalus),
among our earliest spring migrants, arrive in three waves -- old males,
females, and first-year males. The mature males are a robin-size (ten inch)
marsh blackbird with an orange-yellow head and breast, and reveal a white
wing patch in flight. The yellowheads return year after year to their
special nesting sites, where they congregate in colonies, some of which
are very large.
Reaching the breeding grounds first, the mature males stake out their claims
in tall reeds and tules in swamps or sloughs that are very wet and have
permanent open water. The females arrive a few days later. The males pursue
them around the swamp, bowing their heads and spreading their tails in
courtship display while perched on the reeds.
The smaller females, brownish birds with yellow face, throat, and chest,
build the nest and incubate the eggs without help from their mates, which
assist only in caring for the young after they leave the nest. Nest building
usually begins about the first of May, and continues well into June. This
lengthened nesting time results from predation of eggs and young by mink,
owls, weasels, water snakes, marsh hawks, crows, foxes and muskrats; also
from destruction of nests by severe storms. Only one brood is raised in a
season, in contrast to the red-winged blackbird which incubates two to three
broods, but may raise only a few of the fledglings.
The nest, 8" to 10" high, is made of wet plant materials collected from the
water near by. This is cleverly woven about the reed stems, two or three feet
above the water, and forms a tight basket when dry. It is lined with broad,
dry reed leaves. Thomas S. Roberts writes, "A skillful, industrious bird will
build one of these large, beautifully woven and lined nests, all complete
in two to four days. When it is considered that a single bird has not only
to collect, but skillfully to manipulate all this large mass of material,
it is surprising to see these bulky nests spring up almost over night."
The three to five grayish or greenish-white, blotched eggs hatch in ten days;
within twelve days the young are learning to climb among the reeds. Their
feet are large, with long strong toes, which help them walk on mud or
floating vegetation. After the nesting period ends, young and adults gather
again in flocks and migrate south, often leaving in early September.
The yellowheads feed on aquatic insects, and also fly to nearby fields to
devour great numbers of earthworms, beetles and grubs, ants, grasshoppers,
caterpillars, weevils, weed seeds and waste grain. In spring, because they
may be observed with other blackbird species, they share proportionately
the blame for damage to newly planted farm crops. But this species does play
an important role in controlling grasshoppers and other harmful insects.
The yellow-headed blackbirds are poor singers, producing with much effort a
harsh jumble of notes ending in a rasping buzz. The breeding range is from
central British Columbia, western United States, south to southern California.
They winter in southern Mexico.
-- by Marie L. Atkinson
REFERENCES:
Field Guide to Western Birds -- Roger Tory Peterson
Song and Garden Birds -- National Geographic Society
Yellow-headed Blackbird -- Thomas S. Roberts
|
|