Color illustrations appear in Mayfield (1960) 

 and the various field guides. 



RANGE 



Kirtland's warbler breeds in the northern 

 Lower Peninsula of Michigan and winters in the 

 Bahama Islands (Mayfield 1960). Strays have re- 

 cently (1977, 1978) been observed near Peta- 

 wawa, Ontario, Kazabazua, Quebec, and Black 

 River Falls, Wisconsin (Ryel 1978b). Lane (1975) 

 observed a male and female near Veracruz, Mexi- 

 co in 1974. The strays are not believed to be evi- 

 dence of additional populations (H. Mayfield, 

 pers. comm.). 



RANGE MAP 



The known distribution of the Kirtland's 

 warbler is depicted on the following map (KWRT 

 1976). 



STATES/COUNTIES 



Breeding 



Michigan Alcona*, Alpena*, Clare*, Crawford, 

 Iosco, Kalkaska, Montmorency*, 

 Ogemaw, Oscoda, Otsego*, Presque 

 Isle*, Roscommon, Wexford. 



*historical breeding localities in which the warb- 

 ler has not been recorded since the 1972 breeding 

 survey (Ryel 1978a). 



HABITAT 



This warbler has very specific breeding habitat 

 requirements, including stands of jack pine {Pinus 

 banksiana) 2 to 6 m high (8 to 21 years old) inter- 

 spersed with many small openings, mmimal 

 ground cover, and little or no hardwoods.The 

 stands are usually on Grayling sands which drain 

 very rapidly. Jack pine stands supporting breeding 

 Kirtland's warblers are usually 30 ha or more in 

 area. Historically, fire maintained the habitat by 

 killing mature jack pines and opening up the 

 forest for natural regeneration. The warbler then 

 used these immature stands until they beccmie too 

 old. 



The preferred wintering habitat on the Baha- 

 ma Islands is not known, but Radabaugh (1974) 



suggests use of low, broad-leafed scrub, the pre- 

 vailing form of vegetation. 



FOOD AND FORAGING BEHAVIOR 



A variety of insects are taken from the ground, 

 air, or pine foliage. Kirtland's warblers often 

 hover at the ends of branches as they pluck in- 

 sects out of the pine needle clusters. They also 

 eat berries. 



SHELTER REQUIREMENTS 



Not known. 



NESTING OR BEDDING 



The ground nest is built of sedges and grasses, 

 rounded in shape with an inside diameter of 50 to 

 60 mm. Although a cover is not built, the place- 

 ment of the nest under a grass tussock provides a 

 canopy and often a tunnel entrance. 



RITUAL REQUIREMENTS 



Males call from perches or from the ground. 



OTHER CRITICAL ENVIRONMENTAL 

 REQUIREMENTS 



A breeding pair requires about 12 ha of young 

 jack pine habitat for their territory (KWRT 1976). 



POPULATION NUMBERS AND TRENDS 



In 1951, there were an estimated 432 singing 

 males; in 1961, 502; and in 1971, 201. In the 7 

 years since then (1972-78), there have been 200, 

 216, 167, 179, 200, 218, and 196 singing males 

 counted on the breeding ground (Mayfield 1975, 

 Ryel 1978b). In 1974 and 1978, there were unex- 

 plained declines in singing males (Ryel 1978b). 

 Mayfield (1953) stated that females and males are 

 about equal in numbers; thus, the 1978 total for 

 the species could be estimated at 400 individuals. 



REPRODUCTION 



They generally lay five eggs, which hatch in 

 mid-June. Prior to cowbird control, nesting suc- 

 cess averaged 1.4 fledglings per pair. After the 

 cowbirds were trapped, the success rate rose to 

 4 fledglings per pair. 



