records from California, Michigan, and several locations in northern Mexico. The white-collared swift inhabits a large variety of landscapes. It is most common over montane and submontane evergreen forests, and is also found over lowland evergreen forest, secondary forest, and more open habitats like scrublands. In elevation it ranges from lowlands to . Predation The only documented predation on white-collared swifts was by Virginia opossums, which raid and eat the young in nests, and peregrine falcons, which are known to wait near colony entrances to take birds as they enter or leave. Behavior Movement The white-collared swift is usually considered to be resident throughout its range. However, it has many times been documented beyond its usual northern limit and also makes significant movements to lower elevations to escape bad weather. Feeding Like all swifts, the white-collared is an aerial insectivore. Details of its diet are lacking, but a pair of specimens from southern Mexico had fed almost exclusively on flying ants. It often feeds in flocks of 200 or more that sometimes include other swift species. It has a powerful, fast, and direct flight, and will ascend thermals to great heights. White-collared swifts attain or exceed flying speeds of . Breeding The white-collared swift's nesting season in southern Mexico and Costa Rica includes at least April and May; it has not been documented elsewhere. It nests in colonies within caves, which often contain a stream or are behind a waterfall. It builds its nest on a ledge or other protrusion or in a niche, sometimes behind a waterfall. Nests are flattish circles made from some or all of mud, moss, and insect chitin lined with leaves or fern fronds; the materials used can differ between colonies. In two studies they measured in diameter with depths of . The clutch size is two eggs. The incubation period and time to fledging are not known; nestlings become independent 45 to 55 days after hatch. Vocal and non-vocal sounds The white-collared swift's vocalizations have been described as "nasal twitter of chee chee chee, whiss whiss" and "scratchy but not shrill tseet, tchee, and chirrio notes". Flock members may call in unison. A flock makes "an impressive swooshing rush of air" when rapidly descending, as down a valley. Status The IUCN has assessed the white-collared swift as being of Least Concern. It has an extremely large range and an estimated population of at least