270 
EXTRACTS FROM THE FOREIGN PERIODICALS. 
ZOOLOGY.^ 
1. On the Migrations of North American Birds, by the Rev. John 
Bachman. —Migratory birds are admirably adapted for rapid and protracted 
flight. Their light hollow feathers, their bones full of air-cells, their large lungs, 
and the force of their wings, enable them to float a long time in the air with 
little exertion. It has been ascertained that the Migratory Pigeon {Columha mi- 
gratoria)^ and many species of AnatidcE, fly at the rate of a mile and a half in a 
minute. [[Some birds, and especially certain of the Hiriindinidm and Falco- 
nidce^ are supposed to fly occasionally at nearly four times this speed.— Ed.]— 
Thus these birds can, in a single day, travel from Charleston to the northern¬ 
most parts of the U. S., at once explaining the fact of Pigeons having been killed 
in the northern states with undigested rice in their gizzards, which they had 
swallowed, the preceding day, in Carolina or Georgia. A Falcon sent out by 
the Duke of Lerne, has returned from Spain to Teneriffe, a distance of 750 
miles, in 16 hours. 
It is certain that many birds of passage fly during the night; they first ascend 
in the air, from whence they send forth their cries, and many, as the Stork, seem 
scarcely to rest on their course from their winter quarters in the south to their 
breeding places, towards the polar regions. 
Birds emigrate either to avoid the cold of winter, or, probably, to obtain food 
more suitable and more abundant.t In fact, among those which remain in the 
snows of the north, some are omnivorous (as Corvus corax^ C. Canadensis^ and 
other Crows), while others feed on the buds or leaves of trees, as the Pine Thick- 
bill, &c. But the insectivorous species, those which frequent marshes and stag¬ 
nant waters, the borders of rivers, &c., all emigrate, and go to seek in the south 
the kind of food they require. Some birds only migrate from the south to the 
north of the Union, and do not proceed further than Carolina; such are the 
various insessorial birds, as Larks, &c. When the winter birds return to the 
northern regions, they are replaced by analogous species from the tropics. Thus 
in America the White-headed Elanus (Elanus hucocephalus)^ the Mississipi Fal¬ 
con, and others, build in the woods abandoned by the northern raptorial birds, 
so that each season brings a succession of different species. 
* As this is the first ornithological extract we have made from the foreign journals in the pre¬ 
sent volume, we feel assured that no apology is necessary for quoting at such length from the very 
interesting paper of Mr. Bachman. The article originally appeared in the American Journal of 
Science; but our quotation is translated from a French periodical.— Ed. 
f These, doubtless, are the circumstances for which birds are caused to migrate; but it must 
be remembered that birds are impelled to change their abodes at certain seasons by a mere blind 
impulse—an innate faculty, which is stimulated at those periods, and without any reason ar 
knowledge on. their part of the cause of these emigrations.— Ed. 
