“But much as he loves cool weather for nest-building, he tires of it when the first frost touches the valleys, and snow caps the tops of his favorite mountains; for then his insect food grows scarce.  So he changes his summer habits; leaving the guild of Ground Gleaners, and becoming a Seed Sower, he follows the sun toward the tropics, where, likely enough, he tells the alligators long tales of northern lands and assures the water-moccasin that, big snake as he is, the mountain rattlesnake is quicker at biting.

“This Olive-backed Thrush you may hear more often than see—­he is a will-o’-the-wisp for shyness, whether on his journeys or about home.  But remember three things about him:  his back is evenly olive (if you do not know what this dark-greenish color is, look at the olives you have on the table, or that stand in the tall glass jars in the grocer’s window, for if you wish to study birds you must learn to distinguish this color from brown or the bright green); he has a cream-yellow ring round his eye; and lastly, his black-speckled throat and breast are dull yellowish.”

“Won’t you let us go up to the wonder room now and see all these Thrush cousins in a row?” asked Nat, when the Doctor had finished describing them.

“We will go up to the house and you may take a look at them, but I want you to be also able to name them from what I tell you; for when you see a bird out of doors you will seldom be able to have a stuffed one with which to compare it.

“Now we will make a procession of these cousins,” said the Doctor, as they reached his study.  He then opened a glass case, took out six birds, and stood them on the window-sill.  “See, this is the way they go arm in arm when they walk in the great procession of Bird families: 

  “The Bluebird and the Robin;

  “The Wood Thrush and the Veery;

  “The Hermit and the Olive-back.

“Rap, my boy, look at each one and see if you can remember some of the differences between them.  Now shut your eyes and think.

“What has the Bluebird?”

“A blue back and a red and white breast; it is the flag bird.”

“The Robin?”

“A brick-red breast and dark back.”

“The Wood Thrush?”

“A rusty-brown back, the brightest on the head, and a little greenish on the tail.”

“The Veery?”

“An even light-brown back, the same from head to tail.”

“The Hermit?”

“A greenish-brown back, much redder on the rump and tail, like a chestnut.”

“The Olive-back?”

“An even greenish-brown back, the color of olives all over.”

“And the under parts of the last four—­what general color are they?”

“From white to buff, with different sized and shaped dark markings.  The spots on the Wood Thrush are the roundest and blackest; those on the Veery are the smallest, lightest, and most on the throat; on the Hermit they are longer and run together more like stripes; and those on the Olive-back are most like the Hermit’s.”