Chordeiles popetue. 1879. Maine (Lake Umbagog). May 24. One booming over the lake this evening. " 25. Abundant this evening, the males booming in all directions. June 22. Watched a male closely this evening. He worked his way skyward by jerky, moth-like flights until an elevation of several hundred feet had been reached when he set his wings and dove earthward. When within about forty feet of the ground--the distance varying somewhat on different occasions--the tips of his wings were suddenly turned forward and at the same time the remarkable ripping "boom" was heard. The connection at this alteration in the angle at which the wings were held and the production of the sound was too obvious to admit of any doubt that the latter was caused by the wings, instead of being vocal. He invariably came down over the same spot though from various starting points, and I was not surprised when, a little later, the female rose from the ground at the termination of one of his plunges and skimmed off close over the ground, the male following her closely. June 23 I visited the spot about noonday and started the female. She pretended lameness, and tried all her arts to lead me away from the place, so that I felt sure that she had either eggs or young, but on the scorched and blackened ground I could not find them. 1880. May 20. Numbers. June 4. Dozens flying about this evening, mostly in pairs. The males would mount hundreds of feet in the air and then dive down after the flying female overtaking and brushing past them within a few inches, at the same time "booming". 1881. May 14. One booming this evening. " 16. Had a good chance this evening to compare the note of the Nighthawk with that of the Woodcock. They are wonderfully alike but the Woodcock's cry is feebler and cannot be heard more than fifty to a hundred yards. " 29. Nighthawks came around the house in great numbers this evening sealing through the dooryard close to the ground, and alighting in Mr.Abbott's garden as they always do at this season.