"Being disgusted and very angry to find her house invaded, she and her mate have a talk about the matter. Why they do not simply push the strange egg out, we do not know, but instead of that they often fly off for milkweed fibres and silk to make a new nest right on top of the first one, shutting the hateful egg out of sight underneath. Then they begin housekeeping anew, in a two-storied nest like this one, living in the upper story, and keeping the Cowbird's egg locked up in the basement, where no warmth from their bodies can reach it; and so it never hatches. If a second Cowbird's egg is laid, in the new upper story of the nest, the Warblers generally abandon their home in despair, and choose a new nesting place; but sometimes they build a third story over the other two, and thus defeat the evil designs of both their enemies without giving up their home. "This nest of Rap's is a two-storied one, and when I touched the bottom I could feel that there was an egg in the lower story. By and by, when the birds have flown, we will take the nest apart and you can see for yourselves how ingeniously it is made." "To think of all the ways birds have," said Rap; "going to such a heap of trouble for something they could fix with one good push." "What happens when the Cowbird's egg stays in the nest and hatches out? Aren't the other little birds squeezed and uncomfortable?" asked Dodo. "Yes, they are very uncomfortable indeed, and often starve to death; but you must wait to hear about that until we come to the Cowbird himself." "What family does he train with?" asked Nat. "With the Blackbirds and Orioles," said the Doctor. Then the male Yellow Warbler flew out along a branch above their heads, gave his lisping song, that sounded like "sweet, sweet, sweet, sweeter," seized an insect, and went across the garden toward his nest. "I'm going to watch that nest," said Rap, "and if a Cowbird lays in it any more I'll take the wicked old egg away." "Sweet, sweet, sweet," called the Warbler from the bushes. "Maybe he understood you," said Dodo. "I'd believe most anything about birds." The Yellow Warbler (Or SUMMER YELLOWBIRD) Length about five inches. Upper parts rich olive-yellow, brightest on the rump and crown, but dark brown on wings and tail, with the inside half of each tail-feather yellow, and some yellow edgings on the wing-feathers. Under parts bright yellow, in the male streaked with rich brownish-red. A Summer Citizen of the greater part of North America, nesting in orchards and bushes, and going to the tropics in winter. Belongs to the guilds of Tree Trappers and Sky Sweepers. THE YELLOW-RUMPED WARBLER (Or MYRTLEBIRD)