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 orstump. 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 28d of that menth. 
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 
