58 NOETH AMfiUlCAN WARBLEES. 



from Coban,« Guatemala (4,300 feet altitude); and the only record of 

 its capture in South America is that of an adult male taken in the 

 Santa Marta district at Las Nubes,' Colombia (5,000 feet). The win- 

 ter home of the black-throated blue warbler is better defined than 

 that of any other coitnmon warbler, and allows a very exact determina- 

 tion of the square miles of territory occupied by it at this season. 

 Cuba, Haiti, and Jamaica, with a combined area of 74,000 square 

 miles, are doubtless occupied during the winter by the great majority 

 of the individuals of the species. The remaining birds do not prob- 

 ably cover enough territory to bring the'total to 80,000 square miles. 

 This is a small area compared with that occupied during the breeding 

 season, and is about equal to that part of the summer range of the 

 bird which extends along the Atlantic slope in the United States. 



Spring migration. — Outside the lighthouse records, there are almost 

 no spring records of the black-throated blue warbler in Florida, but 

 a full set of data from North Carolina allows a calculation of the 

 approximate time when the species crosses from Cuba to Florida. 

 The average of the earliest spring arrivals noted for eleven years at 

 Raleig-h, N. C, is April 27, with extremes of April 23, 1892, and May 

 2, 1893, in normal migration; in 1888 and 1894 stragglers were seen 

 somewhat earlier. At Asheville, N. C, 2,000 feet above sea level, 

 the average for four years was April 22, with extremes of April 19, 

 1893 and April 26, 1890. The species is one of the few that appear 

 in the mountains earlier than on the plains, and the case seems to sus- 

 tain the theory that the individuals of a species that breed farthest 

 south are the first to migrate in the spiing; hence the inference that 

 the arrivals noted at Asheville were those of birds about to breed in 

 the vicinity, while those at Raleigh were of birds proceeding to more 

 northern breeding grounds. 



It is about 800 miles nearly due north from Sombrero Key, Florida, 

 to Asheville, N. C. Few species of birds migrate in the spring faster 

 than 25 miles per day. At this rate it would require a whole month 

 for the journey of a bird from southern Florida to North Carolina. 

 With the North Carolina dates in mind, we should therefore expect 

 the black-throated blue warblers to be striking the Sombrero Key 

 light in the latter part of March. But as a matter of fact the birds 

 appear there scarcely earlier than in North Carolina. A single bird 

 struck the lighthouse March 9, 1886, and three others March 21, 

 1886. With these exceptions, the earliest dates are April 15, 1885, 

 April 11, 1886, April 19, 1887, and April 14, 1888. This absence of 

 earlier records is not due to lack of weather conditions favorable for 

 striking, for in the spring of 1887, between March 3 and April 13, the 



aSalvin, Ibis, p. 205, 1866; Sharpe, Cat. Birds Brit. Mus., X, p. "651, 1885. 

 !> Allen, Bull. Am. Mus. Nat. Hist, XIII, p. 177, 1900; Auk, XVII, 367, 1900. 



