By Ellen Horowitz
Few birds have names descriptive of their appearance, but the Yellow-headed Blackbird is one that wears its name boldly. Acquaintance with yellow-heads, as they are commonly called, provides a visual treat, an audio surprise and an introduction to the world of the marsh.
Yellow-headed Blackbirds breed throughout western North America, from British Columbia to southwest Ontario, the Great Lakes through the Great Plains to the west coast and southwestern states. In winter, these Neotropical migrants travel as far as southern Mexico. Found across Montana from April to November, Yellow-headed Blackbirds are highly visible and vocal during the breeding season in May and June.
The flamboyant male with bright yellow head, neck and chest, jet-black body, and white wing patches makes this robin-size bird unmistakable. The smaller, less conspicuous female has dull yellow face, throat and breast, and brown body. Its scientific name, Xanthocephalos xanthocephalos, is Greek for “yellow head, yellow head.”
Unlike the melodies of meadowlarks, a member of the Icterid family to which blackbirds belong, the yellow-head’s song resembles a metallic buzz or the creaking of rusty gate hinges. This sound adds to an unusual orchestra that may include the rattling, whirring, croaking, booming and gurgling notes and voices of other more secretive avian marsh musicians, such as Soras, Virginia Rails and American Bitterns.
Yellow-headed Blackbirds, larger than their red-winged cousins, dominate in areas where both are present. Redwing Blackbirds appear early in spring and exploit all areas of a marsh until the yellow-heads arrive. Territorial interactions between the two are an easily observed bird behavior that is part of the springtime ritual at a marsh. Yellow-headed Blackbirds take over the prime real estate, often located near the center of large wetlands, and oust the redwings to shallower water near the edges.
Nesting colonies of Yellow-headed Blackbirds are found where dense cattails and bulrushes grow in two to four feet of water and where insect life is rich. Some colonies contain as many as 25 to 30 nests within a 15 square foot area. Each adult male stakes his claim within the larger framework of the colony. A polygynous breeder, he mates with several females who nest within his defended territory.
The female weaves long strands of wet vegetation around cattails or other tall aquatic plants to form her nest. As the basket-like structure dries, it pulls the supports taught. The location of a nest ranges from 10 to 30 inches above the water. Deep water protects the nest and its occupants from prowling predators — skunks, raccoons and foxes. Tall, thick vegetation hides them from northern harriers and other birds of prey.
During the breeding season, the diet of yellow-headed blackbirds consists primarily of insects and spiders. The birds glean them from the ground, plants, or hawk them from the air. Seeds, including grain, form a major portion of their diet during the rest of the year. Like all Icterids, the yellow-head has a strong, straight, pointed bill and powerful muscles that control its opening and closing. After inserting its bill into the ground or matted vegetation, the yellow-head spreads its bill, which presses against the surrounding substrate to form a cavity. The behavior, known as “gaping,” allows access to hidden food sources.
Yellow-headed blackbirds feed in freshly plowed lands, cultivated fields and pastures during migration. Although they cause some damage to agricultural crops by pulling up seedlings and eating grain, the insects and weed seeds they consume prove more beneficial than harmful.
During autumn migration, male yellow-heads form separate flocks from females and young. Within portions of their range, they are frequently part of enormous winter flocks that include Red-winged Blackbirds, grackles and cowbirds.
Although they aren’t commonly seen during Christmas Bird Counts in Montana, Yellow-headed Blackbirds have, on rare occasions, been found around Bigfork and Ninepipes National Wildlife Refuge, among a few other places in the state.