BARN SWALLOW. 395 
of April. Their northern migration extends to the sources of 
the Mississippi, the Rocky Mountains, and the fur countries, 
where, distant from the habitations of man, they inhabit caves, 
particularly those in the limestone rocks. They retire from 
Massachusetts about the 18th of September, and are observed 
in the same month and in October passing over the penin- 
sula of Florida on their way to tropical America, where they 
probably pass the winter. I have seen a straggling pair in 
this vicinity even on the 15th of October. The fleetness with 
which they move, and the peculiarity of their insect fare, are 
circumstances which would impel a prompt transition to more 
favorable climates. Accidental fits of torpidity, like those 
which occasionally and transiently take place with the Hum- 
ming Bird, have undoubtedly happened to Swallows, without 
proving anything against the general migrating instinct of the 
species, which as long back as the time of Anacreon has been 
generally observed. 
Early in May they begin to build against a beam or rafter, 
usually in the barn. The external and rounding shell is made 
of pellets of mud tempered with fine hay and rendered more 
adhesive by the glutinous saliva of the bird; within is laid a 
bed of fine hay, and the lining is made of loosely arranged 
feathers. ‘They have usually two broods in the season, and the 
last leave the nest about the first week in August. Twenty or 
thirty nests may sometimes be seen in the same barn, and two 
or three in a cluster, where each pursues his busy avocation in 
the most perfect harmony. When the young are fledged, the 
parents, by their actions and twitterings, entice them out of 
the nest, to exercise their wings within the barn, where they sit 
in rows amid the timbers of the roof, or huddle closely to- 
gether in cool or rainy weather for mutual warmth. At length 
they venture out with their parents, and, incapable of constant 
exercise, may now be seen on trees, bushes, or fence-rails, near 
some pond or creek convenient to their food; and their diet 
is disgorged from the stomachs or crops of their attentive 
parents. When able to provide for themselves, they are still 
often fed on the wing, without either party alighting ; so aérial 
