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Setophaga kirtlandii (Baird, 1852)
Kirtland's Warbler
Federal Protection: Listed Endangered
State Protection: Endangered
Global Rank: G3
State Rank: SNRN
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: High Conservation Concern
Element Occurrences (EOs) in Georgia: 0
Habitat Summary for element in Georgia: Transient; varying habitats during late spring and fall
This small songbird is about 14.5-15.0 cm (5.75-6.00 in) in length and weighs 12-16 grams. Males have dark bluish gray upperparts while females have somewhat lighter gray upperparts, both have dark streaking on their backs. The throat, chest, and abdomen of both sexes are yellow with dark streaking or spotting on the flanks and both have a white vent, white wingbars, and broken white eye-ring which contrasts with the dark eye. Bill and legs are dark gray to black in color.
The Canada warbler (Cardellina canadensis) resembles the Kirtland's warbler, but has yellow on the lores (area of face at base of upper bill), a complete eye-ring, no wingbars, and no streaking on its back. Additionally, the Canada warbler has a "necklace" of dark streaking across its upper chest. The streaking of the male's necklace is black while the female's is gray. There is no streaking along the flank of the lower chest and abdomen of the Canada warbler like there is on the Kirtland's warbler. Adult yellow-rumped warblers (Setophaga coronata) in breeding plumage differ from the Kirtland's in having white underparts with heavy dark streaking, a whitish throat, dark mask with white superciliary stripe, and yellow rump. The male yellow-rump also has a yellow crown in breeding plumage and both sexes have a yellow patch on the flank under the base of each wing. Another warbler similar in appearance is the magnolia warbler (Setophaga magnolia), which in breeding plumage has a yellow throat, breast, abdomen, vent, and rump with black streaking on the upper chest and along the flanks. It has white wing bars, a narrow white line over the eye, and a dark mask on the face. The male's mask is black while the female's is dark gray. There is also a wide white lateral band across the upper surface of the tail about midway between the base and the tip. One behavioral cue that sets the Kirtland's warbler apart from these other gray-backed warblers is a tendency to bob or wag its tail.
The Kirtland's warbler nests in large stands (>30 ha, but normally 120-160 ha or larger) of young jack pine (Pinus banksiana) that are 6-22 years old (about 1.5-6.0 m tall) and surrounded by extensive areas of pine forest. During migration it is most often seen in low broadleaf scrub in somewhat open locations. In winter it uses dense (Caribbean) island scrub and the understory vegetation of pine forests.
Centipedes, caterpillars, sawfly adults and larvae, grasshopper nymphs, moths, deerflies, horseflies, crickets, blueberries, and pine sap in summer; berries and insects in winter.
Spring migration occurs between late April and mid-May when the Kirtland’s warbler leaves its wintering grounds in the Bahama Islands, Turks and Caicos, and possibly Cuba. Until recently, many researchers thought migration flights between breeding and wintering sites were likely done in a single hop. This, coupled with this bird's rarity, seemed like a feasible explanation for the dearth of records outside of its breeding and wintering grounds (e.g., only 12 records of this bird exist for Georgia, with only 6 during the last 50 years). However, recent research using birds fitted with light-level geolocators led to the discovery that Kirtland’s warblers exhibit a loop migration pattern with one to several stopover sites along the way. In spring, the birds cross from the western Bahamas to peninsular Florida where many make a stopover that lasts an average of nearly 5 days. A second stopover (that also lasts almost 5 days) occurs in north Florida, southeastern Georgia, or southwestern South Carolina. The last stopover occurs near the western shore of Lake Erie in northern Ohio or southern Ontario. It lasts an average of just over 2 days. From here most birds fly to northern Lower Michigan, but some travel to the Upper Peninsula of Michigan, Wisconsin, and Ontario. The entire spring migration takes about 16 days to complete.
Males arrive on the breeding grounds a few days ahead of females. Pairing usually occurs within a week and nest building may start a few days later, but can be suspended by cold, wet weather for as long as two weeks. The female constructs the nest on the ground from sedges, pine needles, and small twigs, and lines it with rootlets, deer hair, moss, and grassy fibers. It is usually well concealed by a low, overhanging branch of a pine tree, grasses, or low shrubs. Three to five eggs are laid within 5-6 days. Incubation takes 13-15 days and is done by the female, with the male carrying food to her on the nest. Fledging occurs about 9-10 days after hatching, and independence from the parents usually occurs in about a month. Foraging consists of gleaning insects and other invertebrates from pine needles, leaves of deciduous trees, and ground vegetation, and occasionally these birds will hover to catch flying insects or snatch insects from the ends of pine branches. They also eat blueberries when available. Feeding is concentrated near the ground and midlevel of small pines.
Birds start fall migration anywhere from late August through early October. Most move in an eastward direction from the breeding grounds to areas in southeastern Ontario, northwestern Pennsylvania, and western New York, where they likely spend time feeding. From there they head due south to the coast of the Carolinas where they spend more time refueling before flying out over the ocean to the western Bahamas. Average migration duration in fall is about 18 days. This species is almost always solitary on the wintering grounds.
Light-level geolocator technology has given us the first definitive evidence that Kirtland’s warblers regularly travel through Georgia during migration. Unfortunately, this technology does not provide precise location information. In 2017, the Cornell Lab of Ornithology initiated a Kirtland’s warbler migration blitz using volunteer surveyors. This effort used specific protocols to try to document migrating Kirtland’s warblers in Florida, Georgia, and South Carolina. Unfortunately, no Kirtland’s warblers were detected in Georgia during this survey effort. At present there appears to be no way to effectively survey this species in Georgia during migration. With nanotag technology quickly advancing it might be possible to track Kirtland’s warblers from breeding to wintering grounds in the near future. Thoroughly documenting the locations, dates, and conditions of any new occurrences in the state would be useful.
The majority of the breeding range of the Kirtland's warbler is restricted to the northern portion of Michigan's Lower Peninsula with a few smaller populations or nesting pairs located in Michigan’s Upper Peninsula, Wisconsin, and southern Ontario. This species winters in the Bahamas, with small numbers wintering in the Turks and Caicos islands, and possibly a few wintering in Cuba.
Habitat loss on the breeding and wintering grounds and brown-headed cowbird (Molothrus ater) parasitism are the greatest threats to the Kirtland's warbler. Until very recently modern fire control had led to a reduction in the amount of forest burned each year, thereby reducing the amount of fire-dependent jack pine breeding habitat that regenerated. Currently the wintering habitat in the Bahamas seems to be secure, but future development could have a substantial negative impact on the scrub and pine forests used by this species. Natural disasters such as hurricanes or tropical storms could significantly reduce wintering habitat through direct destruction and through the impacts of saltwater intrusion. Brown-headed cowbirds are thought to have been a major factor in the decline of the Kirtland's warbler during the 20th century, particularly in the 1970s and 1980s. The cowbird, a brood parasite, lays one or more of its eggs in the warbler's nest, leaving the egg and offspring to be reared by the warbler. The warbler is incapable of distinguishing the cowbird eggs or chick(s) from its own young, and the young cowbirds are larger and able to out-compete the young warblers when they hatch. Young warblers often die of starvation or are forced out of the nest by the young cowbirds.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Natural system modifications | Invasive & other problematic species, genes & diseases | Biological resource use |
| Specific Threat | Fire & fire suppression | Invasive non-native/alien species/diseases | Logging & wood harvesting |
There are no sites where this species has occurred regularly in recent decades. Most records are from the immediate coast including four sightings on Cumberland Island, and one sighting each at St. Simons Island, Jekyll Island, Savannah, and St. Marys.
Surveys of singing males showed significant declines in numbers from 1961 when there were 502, to 1974 when only 167 were found. Yearly surveys throughout the 1970s and 1980s recorded from 167 to 243 singing males. By the early 1990s numbers abruptly increased, a trend that has continued to the present with the number of singing males reaching 2,365 in 2015. Much of this increase can be attributed to increases in habitat management activities for this species such as planting of jack pine and prescribed burning and continued trapping of brown-headed cowbirds at breeding sites. This management will continue into the foreseeable future. Better knowledge of the migratory pathway, critical stopover areas, and winter habitats will also help long-term conservation of this species.
Bocetti, C. I., D. M. Donner, and H. F. Mayfield. (2014). Kirtland's Warbler (Setophaga kirtlandii), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Cooper, N. W., M. T. Hallworth, and P. P. Marra. 2017. Light-level geolocation reveals wintering distribution, migration routes, and primary stopover locations of an endangered long-distance migratory songbird. Journal of Avian Biology 48:209-219.
Mayfield, H. F. 1960. The Kirtland's warbler. Cranbrook Institute of Science, Bloomfield Hills, Mich. 242pp.
Radabaugh, B. E. 1974. Kirtland's warbler in its Bahama wintering ground. Wilson Bulletin 86:374-383.
Sykes, P. W. Jr. 1989. Kirtland's warbler on the wintering grounds in the Bahamas Archipelago: A preliminary report. Page 28 in Proceedings of the Kirtland's warbler symposium. U.S.D.A. Forest Service, Lansing, Mich.
Sykes, P. W. Jr., and M. H. Clench. 1998. Winter habitat of Kirtland's warbler: an endangered nearctic/neotropical migrant. Wilson Bulletin 110:244-261.
Walkinshaw, L. H. 1983. Kirtland's warbler: The natural history of an endangered species. Cranbrook Institute of Science, Bloomfield Hills, Mich. 207pp.
U.S. Fish and Wildlife Service. 2019. Kirtland's Warbler (Setophaga kirtlandii) Fact Sheet. http://www.fws.gov/midwest/endangered/birds/Kirtland/kiwafctsht.html
U.S. Fish and Wildlife Service. 2019. Midwest Region Endangered Species. Kirtland's Warbler Census Results: 1951, 1961, 1971 thru 2015 (Last updated: May 29, 2019). https://www.fws.gov/midwest/endangered/birds/Kirtland/Kwpop.html
Todd M. Schneider
T. Schneider, 1999: original account
T. Schneider, July 2010: modified and edited text
K. Owers, July 2010: updated status and ranks, added picture
T. Schneider, November 2019: modified and edited text
