Australian Warblers: Acanthizidae

Physical characteristics: Yellowheads measure 6 inches (15 centimeters) in length, and weigh 0.7 ounces (20 grams). Their uppersides are olive with a bright yellow head and yellow breast.

Geographic range: Yellowheads can be found on South Island of New Zealand, including Marlborough, Nelson, Westland, western Otago, Southland, and near Dunedin.

Habitat: Yellowheads inhabit forest areas, especially those that are dominated by beech trees.

Diet: Yellowheads forage throughout the day in the shaded canopy, the upper layer of the forest, or upper subcanopy, layer just below the canopy. They are primarily insectivores, insect eaters, picking insects from the foliage, branches, and trunks, and sometimes even dead wood. Yellowheads prefer larvae, the newly hatched, wingless forms of insects. They sometimes eat fruit, flowers, and fungi.

Behavior and reproduction: During the non-breeding season, yellowheads form large flocks, and are joined by other bird species. During the breeding season, yellowheads live in pairs or trios and are distributed over a large home range. Their mechanical-like call is varied, with six to eight notes repeated rapidly.

During the breeding season, yellowheads live in pairs or trios and are distributed over a large home range. (Illustration by Amanda Humphrey. Reproduced by permission.)

The yellowhead engages in cooperative breeding, and is possibly polygamous (puh-LIH-guh-mus), having more than one mate. They breed from October to February. They build cup-shaped nests in holes. Clutch sizes are typically three to four eggs that are pinkish with reddish brown blotches. They are incubated only by the female for a period of eighteen to twenty-one days. The young fledge at twenty-one days. Two or three adults continue to feed them after fledging for up to fifty-five more days.

Yellowheads and people: There is no known significance between people and yellowheads.

Conservation status: Yellowheads have been declared Vulnerable. Their population has declined significantly due to loss of forest, and their habit of avoiding edges, stunted, and regrowth forests. They are not as vulnerable to nest predators as many New Zealand birds because they nest in holes, but the young birds that are newly fledged often face risk from predators. ∎