Kirtland’s Warbler
Kirtland's Warbler
Setophaga kirtlandii
At a Glance
One of our rarest songbirds, Kirtland's is a relatively large warbler that forages slowly, close to the ground, wagging its tail up and down. It nests only in stands of young jack pines in central Michigan, a habitat that grows up only briefly after fires, and its nests have been heavily parasitized in recent decades by Brown-headed Cowbirds. Controlled burning to create more habitat, and control of cowbird numbers, have helped the warbler somewhat, but it is not necessarily out of danger yet.
All bird guide text and rangemaps adapted from Lives of North American Birds by Kenn Kaufman© 1996, used by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Category
Perching Birds, Wood Warblers
IUCN Status
Near Threatened
Habitat
Forests and Woodlands, Shrublands, Savannas, and Thickets
Region
Florida, Great Lakes
Behavior
Direct Flight, Flitter
Population
4.800
Range & Identification
Migration & Range Maps
Arrives on nesting grounds mostly in mid-May, and gradually departs during August and September, migrating to the Bahamas. Very seldom seen in migration, probably because of the needle-in-a-haystack challenge of finding such a rare bird.
Description
6" (15 cm). Blue-gray above, yellow below, with black streaks along sides, narrow white crescents above and below eye. Wags its tail up and down while perched. This rare bird should be identified with caution; compare to Palm and Prairie Warblers, also Magnolia, Pine, and Canada Warblers.
Size
About the size of a Robin, About the size of a Sparrow
Color
Black, Blue, Gray, White, Yellow
Wing Shape
Rounded
Tail Shape
Notched, Square-tipped
Songs and Calls
Low pitched, loud, bubbling, and rising at the end.
Call Pattern
Flat, Undulating
Call Type
Chirp/Chip, Whistle
Habitat
Young jack pine; winters in dense understory of pines. Breeds only in large stands of young jack pines from 5-25' tall. Jack pine grows on sandy soils, and regenerates only after fires. In migration, seen in thickets and deciduous trees. During winter, rarely seen, found only in dense undergrowth of pine forests of the Bahamas.
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Behavior
Eggs
4, sometimes 3-6. Buff or pinkish-white with brown spots at larger end. Incubation is by female only, 13-15 days; males feed females on nest during incubation. Up to 70% of nests are parasitized by Brown-headed Cowbirds in areas where there is no control of cowbirds by humans.
Young
Fed by both parents. Young leave nest at age of 9 days, do not fly well at first. Parents continue to feed young up to 6 weeks. Usually 1 brood, rarely 2.
Feeding Behavior
Forages for insects near the ground and in lower parts of pines and oaks. Will hop on ground to probe for insects. Gleans insects from pine needles and other vegetation, and occasionally takes items while hovering. Solitary in its foraging in winter.
Diet
Mostly small insects, some berries. In summer, eats many insects, including sawfly adults and larvae, grasshopper nymphs, moths, and flies. Adults also feed on pine sap and blueberries. May feed soft berries to young. In winter in the Bahamas, feeds on insects and small fruits.
Nesting
Males arrive on breeding grounds in mid-May, a few days before the females, and establish large territories. Tend to be loosely colonial (lone pairs are rare), and males tend to return to the same colony in which they previously nested. Males sometimes have more than one mate. Nest: Placed on ground in sandy soil close to pine. Nest (built by female) is open cup made of grass, sedge, pine needles, oak leaves, lined with rootlets, hair, moss, and fibers.
Climate Vulnerability
Conservation Status
Endangered. Always known as a scarce bird with a limited range, Kirtland's Warbler apparently began to decline seriously in the 1960s; census numbers dropped from 502 singing males in 1961 to only 201 in 1971. Through most of the 1970s and 1980s, the annual counts hovered around 200 males, twice dropping as low as 167. Since 1990 the numbers have gradually increased. The tally of singing males topped 1,000 for the first time in 2001, increased to 1,700 by 2007, and hit 2,000 in 2012. Although these are still dangerously low numbers for a songbird, the trend is encouraging. Conservationists are helping the bird by providing more habitat (controlled burning creates the stands of young jack pines needed by the warbler) and by controlling the numbers of parasitic cowbirds in the nesting areas.