April, and start on their southward journey
during late September and early October.

"After mating they either choose separate nesting places, or keep
together in colonies. In early autumn they gather in great flocks along
the borders of rivers, ponds, and lakes, often also on sea beaches,
where they fly to and fro, as if strengthening their wings for the long
flight they intend to take. It has been recently discovered by the Wise
Men that these birds, who had been supposed to eat nothing but insects,
feed at this time upon the same bayberries of which the Yellow-rumped
Warbler is so fond; and that is one reason why they stay by the sandy
wastes where these bushes grow. But no doubt Rap could have told us
that, if we had asked him about it. Another reason for lingering near
water is, that winged insects fly about wet places later in the season
than they do in dry ones."

"But you have left out the Chimney Swallow," said Nat; "and there are
plenty of them all about everywhere." "I have not left him out. Have
you forgotten that he does not belong to the Swallow family? Though he
looks like a Swallow and flies like one, the Wise Men know that he is
not a song bird, and have put him where he belongs--with the Birds that
Croak and Call, next to the Hummingbird and Nighthawk. They call him the
Chimney Swift, because he flies so fast, and you must always give him
his right name.

"If you write very carefully in your little books the description of our
four common Swallows, you will not find it difficult to name them when
you see them. We will begin with the largest--the Purple Martin."

"Why is it called 'Martin'?" asked Rap. "Did somebody named Martin find
it, as Mr. Wilson found the Thrush they named after him?"

"No, my boy, the name comes from a Latin word, meaning 'warlike' or
'martial,' because in the Old World certain Swallows there called
Martins were considered good fighters, and very brave in driving away
Hawks and other cannibal birds. Don't you remember that Mars was the God
of War in classic mythology, and haven't you heard soldiers complimented
on their fine _martial_ appearance?"

The Purple Martin

Length seven and a half inches.

Upper parts shining blue-black, not quite so glossy on the wings and
forked tail.

Under parts the same as the upper in the male, but grayish-white in the
female and young ones.

Song rich and musical, of two or three flute-like notes. Nest made of a
few leaves or straw