Kirtland's Warbler

The Kirtland's Warbler (Setophaga kirtlandii), also known as the jack pine bird in Michigan, is a small songbird belonging to the New World warbler family (Parulidae). This species, once on the brink of extinction, has made a remarkable recovery thanks to concerted conservation efforts. The male Kirtland's Warbler is characterized by bluish-grey upper parts with dark streaks on the back, a yellow belly, and dark streaks on the flanks and sides. It has black lores and a distinctive, large, broken white eye ring. Females and juveniles are similar but less boldly marked and browner on the wings and back.

Identification Tips

Adult males are identifiable by their bluish-grey upper parts, yellow bellies, and the broken white eye ring. They frequently bob their tails, a behavior uncommon among northern warblers. The Kirtland's Warbler is the largest of its genus, measuring 14–15 cm in length and weighing 12.3–16 g, with a wingspan of approximately 22 cm. Its song, a loud chip-chip-chip-too-too-weet-weet, can be heard from great distances.

Habitat

The Kirtland's Warbler breeds in young jack pine forests on sandy soil, requiring stands of trees aged 6 to 20 years. These habitats are typically created by wildfire or human intervention through logging and planting. In winter, they are found in low coppice habitats, particularly in areas regrown after agricultural abandonment.

Distribution

The Kirtland's Warbler breeds in the Great Lakes region, including Ontario, Wisconsin, and Michigan, particularly in the northeastern Lower Peninsula. It winters in the West Indies, including the Bahamas, Cuba, and the Turks and Caicos Islands, with some overwintering in the Dominican Republic and Florida.

Behaviour

Yearlings and first-time breeders explore to find new breeding grounds, while ringed males often return to the same nesting locality. The warbler occupies a breeding territory of 2.7 to 3.4 hectares and a larger wintering territory of 6.9 to 8.3 hectares. They construct their nests on the ground, well concealed by vegetation.

Song & Calls

The mating song is a loud chip-chip-chip-too-too-weet-weet, often sung from the top of a dead tree or northern pin oak clump. In winter, the bird makes loud "chip" noises from low in dense bushes.

Breeding

Kirtland's Warblers lay eggs in May to June. The eggs are pinkish white, with brown and pink sprinkles concentrated at the larger end. The nest is usually at the base of a tree, next to a down log or other structure.

Similar Species

The Kirtland's Warbler can be confused with Setophaga coronata but is distinguishable by its nearly uniformly yellow belly, absence of a conspicuous yellow rump or crown, and a larger bill and feet.

Diet and Feeding

In winter, the warbler feeds heavily on berries of Lantana involucrata and other fruits. During the summer, it consumes blueberries and insects such as spittlebugs, aphids, and ants.

Conservation status

The Kirtland's Warbler is currently classified as Near Threatened by the IUCN and Vulnerable by NatureServe. Conservation efforts, including habitat management and cowbird control, have been crucial in the species' recovery from a low of 167 singing males in 1974 to a population of over 2,300 pairs by 2018.

Protected areas

The Kirtland's Warbler is regularly recorded in protected areas such as Abaco National Park in the Bahamas, Algonquin Provincial Park in Ontario, Canada, and Huron-Manistee National Forests in Michigan, USA.