Francis H. Allen (MS.) writes the two common songs as "_quee quee quee-e-e´_" and "_que-que-que-que quee-ee´_," and says further, "in June 1907, I heard a bird in Shelburne, Vt., that sang persistently a short song like _k[=u] quee-e-e´_ besides singing occasionally one of the ordinary songs. In May, 1910, at Jaffrey, N. H., I heard a bird sing over and over _qui-qui-qui-qui-qui-qui-qui-qui-quee´_, but most of the birds of the region seemed to sing _zee zee zee-ee_, with a falling inflection, while some sang the ordinary _quee quee quee-e-e´_, with rising inflection. The _quee_ songs have a nasal tone. The call note is a dry _chut_ or _chet_, resembling the _chip_ of the black-throated green but not so thick." Mrs. Nice (1930b) describes four different songs; and Gerald Thayer, in Chapman (1907), gives four main songs, with variations, but the versatility of this singer seems to be well enough shown in the previous descriptions. _Field marks._--The male black-throated blue warbler could hardly be mistaken for anything else; there is no other American warbler that is at all like it. The blue back, the extensive black throat, the white patch near the bases of the primaries, the white under parts, and the white spots on the inner webs of the three outer tail feathers are all diagnostic. Fortunately, the fall plumage is essentially the same. But the female is one of the most difficult of the warblers to recognize, olive-green above and buffy below; the only distinctive marks are the white patches in the wings and tail, similar to those of the male, but smaller, duller, and sometimes obscure. _Fall._--As soon as the molting season is over, late in August, old and young birds begin to drift away from their summer haunts; most of them depart from New England during September or even late August. Birds from New England and farther north pass through the Atlantic Coast States to Florida and the West Indies, while those from the interior migrate slightly southeastward and across the lower Alleghenies to join them. Professor Cooke (1904) writes: Black-throated blue warblers strike the lighthouse at Sombrero Key in greater numbers than any other kind of bird, particularly during the fall migration. * * * In five years' time they struck the light on seventy-seven nights, and as a result 450 dead birds were picked up on the platform under the lantern. Probably a still larger number fell into the sea. Adding to these those that were merely stunned and that remained on the balcony under the light until able to resume their journey, the keeper counted 2,000 birds that struck. There were two nights, however, when the numbers of this species were so great that no attempt was made to count them. The Fowey Rocks lighthouse was struck on thirty different nights. It is certain, therefore, that the black-throated blue warbler passes in enormous numbers along both coasts of southern Florida.