FOR a number of years a crested flycatcher has built his nest in a hole in an apple tree in my yard, about twenty feet from a house constructed for the habitation of the wrens. Jenny usually showed no animosity toward her neighbor; but one spring, while nest-building was in progress, she suddenly seemed to have decided that the flycatcher's abode was in too close proximity to her own domicile and deliberately invaded the flycatcher's domains and dumped the materials of his nest on the walk beneath the tree. When the flycatcher returned the air was filled with his protests, while the wren saucily and defiantly answered him from the roof of her own dwelling. The flycatcher immediately proceeded to build anew, but before he had fairly commenced, the pugnacious wren made another raid and despoiled his nest again. This happened a third time; then the flycatcher and his mate took turns in watching and building. While one went out in search of building material the other remained on guard just inside the door. The situation now became exceedingly interesting, and at times ludicrous. Jenny Wren is a born fighter, and can whip most birds twice her size, but she seemed to consider the flycatcher more than a match for her. The first few times after the flycatcher made it his business to stay on guard, the wren would fly boldly to the opening, but would flee just as precipitately on the appearance of the enemy from the inside. After each retreat there was a great deal of threatening, scolding, and parleying, and Jenny several times seemed fairly beside herself with rage, while the flycatcher coolly whistled his challenge on the other side of the line of neutrality. The wren now adopted different strategy. She flew to the tree from a point where the flycatcher could not see her, then hurried along the limb in which the flycatcher lay concealed and circled around the hole, all the time endeavoring to take a peep on the inside without herself being observed, in the vain hope that her enemy might not be at home. Suddenly there would be a flutter of wings and a brown streak through the air, followed by another as the flycatcher, shot like a bullet from the opening in the tree; but the active marauder was safely hidden amid the grapevines, and the baffled flycatcher returned to his picket line, hurling back epithets and telling Jenny that he would surely catch her next time. In this manner the strife continued for several days. Then a truce seemed to have been arranged. Certainly the flycatcher was still on guard, but the wrens went about their work and did not molest the flycatchers except at long intervals. I thought the flycatchers had conquered; but one morning when I came out, there on the walk were three broken, brown-penciled eggs, nest, snakeskin, and all. The flycatcher had put too much trust in the wren's unconcernedness, and came back to find himself once more without a nest. But Jenny seemed to have desired only one more stroke of revenge, and the flycatchers finally succeeded in raising their family in front of the home of Jenny Wren.