It runs in the blood; thus, a cat and a tiger are blood relations; the little coon and the great black bear are nearly akin.

A tall broad-shouldered man, with black hair and a full beard, may have a cousin who is short and thin, with yellow hair and no beard.

You see nothing strange in this, because it is something to which you are accustomed.

But with bird families it takes the trained eye of the student to see the likeness there really is between all birds who have had the same ancestors, though it may be hidden under many differences in their size, shape, color, voice, and habits.
"The Robin, like the Bluebird, is found in almost all parts of North America.

In the far Southern States, like Florida, where they take refuge from winter storms, Robins begin to sing in chorus while the weather in the Middle and Northern States is still so cold that it would freeze the music before any one could hear it, even if the birds had courage to sing.