60 NORTH AMEErCAK WARBLERS. 



Fall migration. — The black-throated blue warbler has one of the 

 simplest of fall migration routes. The individuals breeding in New 

 England and to the northward follow the Coast States to Florida and 

 cross to the West Indies, while those from the interior migrate south 

 and slightl}^ southeast to join the eastern birds. First migrants are 

 noted on the average at Chicago, September 1, the earliest date being 

 August 25, 1898. Near Philadelphia the average for six j^ears is Sep- 

 tember 13, and the earliest date September 8, 1898. The earliest 

 migrant at Washington was noted August 21, 1887. Kecords of aver- 

 age date of last birds seen are: Ottawa, September 29; Chicago, Octo- 

 ber 1; Renovo, Pa., October 6, and Frenchcreek, W. Va., October 9. 

 Some latest records are: Ottawa, October 7, 1900; Chicago, October 

 10, 1897; Petitcodiac, New Brunswick, September 5, 1886; Montreal, 

 September 24, 1887; Lewiston, Me., October 3, 1897; Renovo, Pa., 

 October 11, 1897; Washington, October 11, 1888; Frenchcreek, 

 W. Va., and Asheville, N. C, October 15, 1890. The first of the spe- 

 cies to reach southern Florida usualh^ arrive earh^ in September, 

 though few individuals are noted before the middle of the month, fol- 

 lowing which the}^ come in clouds. At the lighthouses large flights 

 are observed every few da3^s from September 13 to November 18. 

 Omitting an accidental occurrence on July 28, the extremes of fall 

 migration at the lighthouses are from September 3 to November 30, 

 or nearl}^ a third of the entire year. In 1888 black-throated blue 

 warblers were quite common from August 5 to November 10 at St. 

 Lucie, on the east coast of Florida. At Raleigh, N. C, most of the 

 fall migrants are seen between October 4 and October 19; and, omit- 

 ting a single stray bird noted November 19, 1885, the extreme dates 

 are September 11 and October 21. Thus the first birds appear at 

 Raleigh just about the time the heaviest flights are passing Sombrero 

 Key. 



Black-throated blue warblers strike the lighthouse at Sombrero 

 Key in greater nimibers than any other kind of bird, particularly dur- 

 ing the fall migration. Although thev were observed to strike the 

 light in spring on twenty-five different nights in the course of five 

 years, the total of their numbers (122) was not large. But in the 

 fall their aggregate is ver}" great. In five years' time the}" 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 mereh^ 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, w^hen the numbers of this species were so 

 great that no attempt was made to count them. The Fowe}' Rocks 

 lighthouse was struck on thirty different nights. It is certain, there- 

 fore, that the black-throated blue warbler passes in enormous numbers 



