“Now, children,” said the Doctor, “write the Hummingbird table before the twilight comes on.”

The Ruby-throated Hummingbird.

Length less than four inches.

Male:  shining golden-green above, with dark purplish wings and tail, the latter forked; glittering ruby-red throat; other under parts grayish, with some white on the breast and greenish on the sides.

Female:  lacks the ruby throat, and has the tail not forked, but some of its feathers white-tipped.

A Summer Citizen of the eastern United States from Florida to Canada.

Though songless, a jewel of a bird, belonging to the guild of Tree Trappers.  Nest a tiny round cup of moss and plant-down stuccoed with lichens; eggs only two, white.

THE CHIMNEY SWIFT

“Now, wouldn’t you like to see the big chimney?” asked Joe.  “The birds go in and out a good deal this time o’ day.  It’s across the road there, where the old house used to be.  The house is all gone, but the chimney is as strong as ever—­I can climb up top and look down at the nests inside.  See! there it is now!” Looking over the fence, they saw a tall stack of worn gray stones, that looked more like a tower than a chimney.  Small blackish birds kept streaming from the top, circling high in the air and darting down again, all twittering as they dropped one after another out of sight, inside the weather-beaten pile.

“Look, children!” said the Doctor.  “These are Chimney Swifts, usually called Chimney Swallows:  and their color is like soot, to match the places they live in.”

“Aren’t they any relations of Swallows?” asked Rap.

“No, my boy; they look like Swallows, but as I think Olive told you once, the Swifts are a family all by themselves.  This one lives in the eastern half of the country in summer, and goes far south for the winter.  When he lives in a wild region, he chooses a hollow tree for his nesting place, as his ancestors always did before there were any houses or chimneys.

[Illustration:  Chimney Swift.]

“The flight of the Swift is so rapid that at times it is almost impossible for the quickest eye to follow him; his wings are very strong, and almost as long as all the rest of his body.  Short and blunt as his tail looks when he flies, each feather ends in a hard sharp point which sticks out beyond the soft part.  They feed on insects which they catch as they dash through the air, and can also break off dry twigs for nest-building without stopping—­sometimes seizing the little sticks in their bills and sometimes in their claws, which are much stronger than those of Swallows.”

“How do they make the sticks stay in the chimney?  What do they set them on, and how do they perch while they are building?” asked Nat, all in one breath.

“Do you remember how the little Brown Creeper propped himself against the tree when he looked for insects?”