Distribution: The breeding range of the broad-tailed hummingbird, Selasphorus platycercus, extends discontinuously from eastern Guatemala north through Mexico north in the western United States through east-central California, Arizona, New Mexico, Colorado, west Texas, to Nevada, Utah, Wyoming, southwestern Montana, and northern Wyoming. The broadtail is a common breeder in the eastern and central parts of the Great Basin. The broad-tailed hummingbird spends the winter in mid-elevation portions of west-central Mexico. Casual to accidental occurrence in winter has also been reported in southern California and in the Rio Grande Valley of Texas (A.O.U. 1998, Bent 1953, Curson et al. 1994, Kaufman 1996, Ryser 1985).
In Utah, the broadtail breeds in riparian or adjacent habitats, both in lower valleys and at higher elevations. Although stream-side habitat is preferred, broadtails in Utah have also been recorded as breeding in aspen, ponderosa pine, Engelmann spruce, subalpine fir, and Douglas fir dominant habitats (Behle 1981; Ryser 1985; Calder and Calder 1992). Breeding in Utah has been confirmed from as high as 3,170 m (10,400 ft) to as low as 1,370 m (4,500 ft) (Behle 1981; H. Frost unpublished data).
Ecology: In Utah, the broadtail is typically more common during periods of migration than during the summer (Behle 1981). However, migration routes, departure/arrival dates, etc., in Utah and elsewhere are unknown. Likewise, habitat preferences during migration are also unknown. Weather patterns, photoperiod, and flower availability are likely key factors in triggering and sustaining migratory restlessness during both spring and fall periods.
In spring migration, males reach southern Arizona in late February or early March, northern Arizona in early April, Colorado in late April to late May, Wyoming in mid-May, and the northern limits of the range in Idaho by late May (Calder and Calder 1992). In Utah, most spring arrival dates recorded are for early May. Behle and Perry (1975) report an early spring date of mid-March (18th), which was likely a reflection of unseasonably warm weather. Spring arrival dates are generally associated with blossom appearance in various species of wildflowers.
Habitat preferences during migration are unknown.
Winter habitat in Mexico consists of oak forest with pines and cypress interspersed at elevations of 2,300 - 3,000 m. At higher elevations, fir forests mixed with oaks are preferred. Locally, broadtails become a subordinate species and feed at flowers not preferred by larger and/or resident hummingbirds at an elevation of 1,500 - 2,500 m. In humid pine-oak forests above 2,500 m, various species of non-hummingbird flowers with open, cup-shaped corollas are used for foraging. Sap is used as a nectar substitute, and insect foraging occurs both on the wintering grounds and during breeding periods throughout the range (A.O.U. 1998, Bent 1940, Calder and Calder 1992).
Breeding begins in early May in the southern portions of the broadtail's range and in early June in the north; breeding usually ends by mid-August. Typically one, but possibly two broods are raised each season (Baicich and Harrison 1997; Kaufman 1996; Calder and Calder 1992).
Nesting coincides with availability of flower nectar. After mating, male and female broadtails go their separate ways. The female raises the young completely by herself. Males that are successful at mating are promiscuous, but likely many males fail to mate each year. Males are very aggressive in holding their territories all summer, but high turn-over can occur from year to year (based on results of banding studies). Because males do not participate in the incubation of eggs or rearing of young, they spend all of their energy attempting to attract females throughout the breeding season.
Nests are from as low as 0.9 cm (3 ft) to as high as 9 m (30 ft) above the ground and are often found overhanging a stream. Re-occupancy of nests has been reported with the same female returning in subsequent years, but different females are known to use the same site in succeeding years. The exterior of the nest is often camouflaged with lichens, bark fragments, and moss. The inside of the nest is lined, typically with spider webbing or other soft material, such as the "cotton" like material associated with cottonwood trees.
First egg dates vary from year to year by as much as 15 days, depending on snow-melt and floral phenology. Usual clutch size is 2 eggs. Incubation is accomplished by the female alone and lasts for 14 - 17 days. Young are altricial and dark-skinned and are tended by the female alone. Young leave the nest and take their first flights at approximately 23 days of age (Baicich and Harrison 1997; Kaufman 1996; Calder and Calder 1992, Curson et al. 1994; Bent 1953).
Habitat Requirements: In addition to the habitat preferences listed above, the broad-tailed hummingbird typically requires stream side areas adjacent to open patches of meadows or grasses with good quantities of wild flowers available throughout the breeding season.