NORTHERN BLACK-THROATED BLUE WARBLER 225 



strike the Sombrero Key lighthouse in Florida around the middle of 

 April, although there are two or three exceptionally early records in 

 March. As the average dates of arrival in New England and New 

 Brunswick are only about a month later, it would seem that the migra- 

 tion is fairly rapid. But the dates of earliest arrival do not tell the 

 whole story, for Frederick C. Lincoln (1939) observed this species in 

 the mountains of Haiti in the middle of May, showing that there are 

 always many late migrants. 



Professor Cooke's records show that this species arrives at Ashe- 

 ville, N. C, a few days earlier than at Ealeigh, N. C, suggesting that 

 this is one of the few species that appear in the mountains earlier 

 than on the plains. 



There is a northward migration west of the Alleghenies correspond- 

 ing almost exactly in time with that along the Atlantic slope. Cooke 

 says that "in southern Louisiana and southern Mississippi the black- 

 throated blue warbler is almost unknown." He gives only very few 

 records for any point south of Indiana, and some of these may have 

 come across the Gulf of Mexico. The inference is that the bulk of the 

 birds that migrate northward through the central States may have 

 crossed the lower Alleghenies into these valleys. According to his 

 records, it takes the birds only about 10 days to migrate from Brook- 

 ville, Ind., to points in Ontario. 



On its migration the black-throated blue warbler shows a preference 

 for the lower shrubbery in various kinds of woodlands, but it may also 

 be seen almost anywhere in such suitable cover in our parks and 

 gardens or about human dwellings. Milton B. Trautman (1940) says 

 that, in Ohio, these and the Canada warblers "were close associates 

 in migration and frequented the same habitat niches." 



In its summer home this warbler is even more of a woodland bird, 

 frequenting heavy deciduous woods where there is more or less thick 

 undergrowth of mountain-laurel, rhododendron, creeping yew, de- 

 ciduous bushes, small saplings, or tiny conifers. My most intimate 

 acquaintance with the black-throated blue warbler was made while 

 visiting at Asquam Lake, N. H., with Mr. and Mrs. Richard B. Hard- 

 ing. From their camp the land slopes downward to the shore of the 

 lake and is heavily wooded with tall white oaks, swamp white oaks, 

 red oaks, beeches, maples, paper birches, and other deciduous trees; 

 there are also some white pines and hemlocks scattered through the 

 forest, and a heavy undergrowth of mountain-laurel, striped maple, 

 witch-hazel, and other shrubbery. The black-throated blue warblers 

 and the veeries were the commonest breeding birds in this area. 



Gerald Thayer wrote to Dr. Chapman (1907) that about Monad- 

 nock, N. H., this is "a bird of the ampler deciduous undergrowth in 

 deep, moist woods — mixed virgin timber or very old second growth. 



