where do nighthawks live
The female probably selects the nest site, usually on unsheltered ground, gravel beaches, rocky outcrops, and open forest floors. Nests are typically out in the open, but may also be near logs, boulders, grass clumps, shrubs, or debris. In cities, Common Nighthawks nest on flat gravel roofs.
Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr. Ziolkowski, D. J. and W. A. Link. The North American Breeding Bird Survey, results and analysis 1966-2013 (Version 1.30.15). USGS Patuxtent Wildlife Research Center (2014b). Available from http://www.mbr-pwrc.usgs.gov/bbs/.
As aerial insectivores, the migrants will feed en route,  congregating to hunt in marshes, rivers and on lakeshores. In Manitoba and Ontario, Canada, it is reported that during migration the nighthawks are seen most commonly in the late afternoon, into the evening,   with a burst of sunset feeding activities. 
The genus name Chordeiles is from Ancient Greek khoreia, a dance with music, and deile, “evening”. The specific minor is Latin for “smaller”. 
Elphick, J. 1995. Atlas of Bird Migration . London: Harper-Collins Publishers, Ltd.
In southern parts of the breeding range, breeding pairs may have a second brood. If this happens, the male feeds the young of the first clutch while the female incubates the second clutch. He will also feed the female. (; Poulin, et al., 1996)
10. Nighthawks nest on buildings in urban and suburban areas. Flat roofs covered with tar paper held in place by rocks are ideal.
I pieced together information from ornithology textbooks and old morphology books to learn that where the large and small intestines meet (where our appendix is), gallinaceous birds, nightjars, and some other birds have paired, blind offshoots called caeca. In the Ruffed Grouse, these caeca grow enormous in winter and then shrink in spring. Within the caeca are bacteria that produce an enzyme that breaks down cellulose, enabling grouse to digest the woody tissue in aspen buds, their primary winter diet.
Forages most actively near dusk and dawn, also during the day and at night, perhaps especially on moonlit nights. Forages mostly in flight, scooping up flying insects in its wide, gaping mouth. Will feed around bright lights at night, taking the insects attracted there. May rarely take insects from the ground.
In male’s courtship display flight, his wingbeats become even more stiff and choppy as he circles and hovers high in the air, calling repeatedly; then he goes into a steep dive, with a rushing or “booming” sound made by air passing through wing feathers at bottom of dive. Landing near female, he spreads his tail, rocks back and forth, and calls. Nest site is on ground or bare open soil, often in a sandy place; also on gravel roofs, sometimes on top of a stump or other raised object. No nest built, eggs laid on flat surface.