418 BULLETIN 2 03, UNITED STATES NATIONAL MUSEUM 



In the following 27 years, five more specimens, four in Ohio and 

 one in southern Michigan, were taken, all during spring migration. 

 Then on January 9, 1879, Charles B. Cory, collecting a specimen on 

 Andros Island of the Bahamas, discovered the winter home of the 

 species. The location of the breeding ground, although many guesses 

 were made about it, remained unknown until 1903, when E. H. Froth- 

 ingham, of the University of Michigan Museum, and T. G. Gale went 

 trout fishing in Crawford and Oscoda Counties in north-central 

 Michigan. There, on the jack-pine plains, they found numbers of an 

 unfamiliar warbler in full song. They preserved one collected by 

 Gale, and when they returned to Ann Arbor, Norman A. Wood identi- 

 fied it as the still little-known Kirtland's warbler. Wood immedi- 

 ately went north to investigate ; on July 8 he found a nest with two 

 young and one egg and on July 9 a nest with five well-grown young 

 (Wood, 1904). 



Kirtland's warbler proved to be restricted to the fairly dense stands 

 of young jack-pines {Pinus hanksiana) that spring up after forest 

 fires. The exact environmental requirements have not been definitely 

 determined; they include a stand of small trees, predominantly jack- 

 pines (though a considerable number of small oaks and other decidu- 

 ous trees may be scattered among them) and a fairly thick ground 

 cover — usually made up of blueberry {Vaccinmm myrtilloides), 

 aromatic wintergreen {Gaultheria procuTubens), bearberry {Arcto- 

 staphylos uva-ursi), sheep laurel {Kalmia angustifoUa) , sweet fern 

 (Comptonia peregrina), or various combinations of these. The 

 warblers first appear in this cover 9 to 13 years after a fire, when the 

 new pines may be barely 5 feet high. The nesting warblers usually 

 occur in very loose colonies varying from a few pairs to hundreds, 

 but isolated pairs have sometimes been found. As the pines grow, 

 they increasingly shade out the ground cover; after 6 to 12 (rarely 15) 

 years, when the pines have become 12 to 18 feet high, the habitat is 

 no longer used by the warblers. A thick, even stand of pines becomes 

 unattractive to Kirtlands sooner than a thin or uneven stand. 



Courtship. — Up to the present, apparently, nothing about the court- 

 ship of Kirtland's warbler has been published. Verne Dockham, 

 who has watched and recorded the arrival of Kirtlands in Oscoda 

 County for 11 years, believes that the warblers are paired when they 

 arrive on the breeding ground. At least, he reports, he always finds 

 a female with each "first-arrival" male. 



On June 8, 1945 (a very late season), northeast of Red Oak, Oscoda 

 County, I watched a pair on their territory all day. The female spent 

 much of her time on or near the ground, apparently searching for a 

 nest site. (Actual construction of the nest began early in the morn- 

 ing, June 10.) The pair kept close together most of the time, with 



