Chimney Swift nesting and roosting sites are often found near bodies of water as these environments host many of the flying insects that swifts forage on. Most populations of Chimney Swift are near or within urban areas, largely because urban roosts (e.g. chimneys, air vents, wells, garages, lighthouses, and silos) are easier to find and much more abundant than natural roosts. Roosts must be sheltered, dark, and have a relatively constant temperature. Roosts may be abandoned when the temperature becomes too hot for the birds.
Natural roosts consist of large hollow trees, tree cavities, and caves. A decline in old growth forest with large trees across North America is a primary reason why roost preference has shifted from natural to urban roosts in modern times, though birds living in rural areas will still make use of natural roosts when available. In Nova Scotia there are 10 records of Swifts nesting in hollow trees instead of chimneys. Only 17 natural nesting areas have been found in Canada.