Kirtland's warbler (Setophaga kirtlandii), also known in Michigan by the common name jack pine bird, or the jack pine warbler, is a small songbird of the New World warbler family (Parulidae). Nearly extinct just 50 years ago, populations have recovered due to conservation efforts. It requires large areas, greater than 160 acres (65 hectares), of dense young jack pine for its breeding habitat. This habitat was historically created by wildfire, but today is created through the harvest of mature jack pine (Pinus banksiana), and planting of jack pine seedlings.
The population of the species spends the spring and summer in their breeding range in the Great Lakes region of Canada (Ontario) and the United States (Wisconsin and Michigan, especially in the northeastern Lower Peninsula), and winters in the West Indies.
Taxonomy
This species was first recorded by Europeans relatively late for a bird from eastern North America. The first specimen was shot at sea somewhere between the Abaco Islands of The Bahamas and Cuba in mid-October 1841 by the ornithologist Samuel Cabot III. However, the specimen was unrecognized as a new species in the private collection of Cabot's father, Boston merchant Samuel Cabot Jr., until it made its way to the Museum of the Smithsonian Institution in the 1860s.
Ten years later the holotype, a juvenile male, was shot on Jared Potter Kirtland's farm near Cleveland, Ohio, in mid-May 1851. It was used to formally describe the species as Sylvicola kirtlandii by Spencer Fullerton Baird in 1852. Baird first attributed the collection to Charles Pease (Kirtland's son-in-law) in his 1852 description, but by 1858 he had changed his story and was attributing it to Kirtland.
In 1858 Baird moved the species, still then only known from his single specimen, to the genus Dendroica, where it remained until the 2010s, when it was reclassified into Setophaga.
By 1865 only four individuals were known to have been collected. Baird lists the male specimen from the Cabot collection, the holotype, a first female specimen shot in 1860 near Cleveland and preserved by R. K. Winslow, and a fourth (which Winslow mentioned had also been killed near Cleveland but had not been preserved). Local naturalist Philo Romayne Hoy also mentioned having possibly seen the species once near the village of Racine, Ohio, in the 1850s.
Etymology
Baird decided to name the bird after Jared Potter Kirtland: "a gentleman to whom, more than any one living, we are indebted for a knowledge of the Natural History of the Mississippi Valley". The generic epithet Setophaga is from the genitive case of Ancient Greek σής, transliterated as sḗs, meaning "moth", and , meaning "eating".
Description
Male Kirtland's warblers have bluish-grey upper body parts, with dark streaks on the back, yellow bellies, and dark streaks on the flanks and sides. It has black lores (cheeks) and a distinctive, large and conspicuous broken white eye ring, which it only shares with Setophaga coronata. Females and juveniles are similar, but are browner on the wings and back and are not as boldly or brightly marked. It frequently bobs its tail up and down, which is uncommon in northern warblers. At and , it is the largest of the numerous warblers formerly classified in the genus Dendroica and is now the largest of the 35 or so species in the currently-accepted Setophaga genus. The Kirtland warbler has a wingspan of . Its mating song is a loud chip-chip-chip-too-too-weet-weet often sung from the top of a snag (dead tree) or northern pin oak (Quercus ellipsoidalis) clump. This song can be heard over 400m away in good conditions. In its overwintering grounds it does not sing but makes loud "chip" noises from low in dense bushes.
The eggs are a "delicate" pinkish white when fresh, fading to a dull white after a time. There are a few scattered sprinkles in various shades of brown and pink, these sprinkles and blotches concentrated at the top or form a sort of wreath at the larger end. The egg is not very glossy. It is 18 by 14mm in size. The shell is very thin.
Similar species
Baird compared and found it most similar to Setophaga coronata, finding it best distinguishable by having a nearly uniformly yellow belly, no conspicuous yellow rump or crown, less black in the feathers of the crown, and a considerably larger and stouter bill and feet. Henninger mentions he finds it to have a certain resemblance to S. magnolia. In The Bahamas it may be misidentified with S. dominica flavescens.