354 NOTES ON THE 



TACHYCINETA BICOLOR (Vieillot). (614.) 

 TREE SWALLOW. 



This bird loses no time in making its northern migrations as 

 early as there is to be found an appropriate supply of food. It 

 is looked for with so much interest by the poet as well as the 

 naturalist, that its arrival could not long escape notice. Quite 

 early in April, when the sun has driven away the cheerless 

 clouds enough to let his rays begin to warm the recently frozen 

 earth a little, and clusters of tiny forms of insect life begin to 

 occupy the air, the White-bellied Swallows, often accompanied 

 by the Purple Martins appear suddenly upon the scene, in lim- 

 ited numbers, as avaunt couriers of the hosts to come when the 

 question of food supply has been assured. Sometimes, after a 

 few hours spent here, as described in connection with the 

 Purple Martins they leave as suddenly and as completely as 

 they came„ and are not seen for five, ten, or even fifteen days, 

 if the season remains exceptionally backward, yet there have 

 been years when all of the conditions referred to being contin- 

 uously unfavorable, they have come early and remained. The 

 time of average arrival may be set down at about the 12th of 

 April in the southern part of the State, not much time there- 

 after passing before reaching all parts. 



In 1884 they were not in the more southern tier of counties 

 till the 27th of April, while in 1875, according to my notes, they 

 arrived in the latitude of Minneapolis by the 8th, and in 1886 

 on the 7th. 



They build their nests about the 15th of May, in holes in 

 trees, or occasionally in the deserted nests of the Barn Swal- 

 lows, or in a hole of a log or stump. The materials involved in 

 its structure are usually dried fine grasses and feathers, very 

 loosely disposed in the cavity occupied. They lay five eggs, and 

 bring out two broods of young. The eggs are clear, roseate 

 white. 



They retire from the State exceptionally early, not even 

 waiting for the first frost. They are usually gone by the 25th 

 of August. In 1870 Mr. W. L. Tiffany, a very competent ob- 

 server, reported them clean gone, with the Purple Martins on 

 the 23d of that month. 



Their departure on that occasion, was noticed by many ob 

 servers of the habits of the birds, as there was an unusual 

 demonstration of preparation by both species for many hours 

 before the final movement took place. The variation of the 



