Archilochus colubris

In most of the breeding range this is the only hummingbird, so identification is easy. Adult males have a red throat and bronze-green back. Adult females have a grayish white throat, usually green crown, and a bronze-green back. Some older females have up to several red feathers on the throat. Juveniles resemble adult females, but subadult males in autumn may show some red in the the throat. Length is about 3.75 inches (7.5-9 cm).

Breeding habitat includes both heavily wooded and open deciduous, mixed pine-hardwood, or pine forests, forest edge, savannas, wetlands, orchards, parks, wooded yards, and gardens (Cadman et al. 1987, Jackson et al. 1996, Johnston and Odum 1956, Oberholser 1974, Palmer-Ball 1996, Robinson et al. 1996, Weidensaul et al. 2013). Nests are typically near the tip of a downward-sloping branch, 0.5-15 meters above the ground or water and are often sheltered overhead by leaves but open below (Robinson et al. 1996, Weidensaul et al. 2013). During migration, these hummingbirds use habitats similar in structure to those used for breeding. Winter habitat includes brushy second growth, deciduous forest, tropical dry forest, tropical deciduous forest, gallery forest, shade trees in coffee plantations and yards, flowering hedges, and citrus groves (Stiles and Skutch 1989, Mills and Rogers 1992, Robinson et al. 1996, Weidensaul et al. 2013).

DENSITY: Density estimates have been reported as 0.8 pairs/10 hectares in cove forest to 0.9-1.2 pairs/10 hectares in chestnut oak forest in the Great Smoky Mountains (Wilcove 1988), 15-30 pairs/100 hectares in clearcut northern hardwood forest in Nova Scotia (Freedman et al. 1981), and 2 individuals/40.5 hectares in upland forest in Arkansas (James and Beal 1986). Unfortunately, such density estimates are unsatisfactory as males are polygamous and will mate with as many females as possible (R. Sargent, pers. comm.). One male defended a feeding territory (flower garden) encompassing 0.1 ha. Females maintain a territory in the vicinity of the nest (Pitelka 1942). If food sources allow, males may occupy territories as close together as 15 meters (Robinson et al. 1996). Although generally solitary, large numbers sometimes congregate around preferred food sources during fall migration. "Hundreds" were observed amid Jewelweed in September 1906 on Point Pelee, Ontario (Bent 1940) and 50 individuals were observed in a field of jewelweed near Racine, Wisconsin on 20 September 1941 (Robbins 1991).

SITE FIDELITY: Exhibits site fidelity. In Costa Rica, 25% of eight banded birds were recaptured in following years. At another overwintering study site (site info not provided in BNA), 10.6% of 1224 banded birds were recaptured in subsequent years (Robinson et al. 1996). In Pennsylvania, 1.3% of 4208 banded birds were recaptured in subsequent years (up to 3 years post-banding for males and up to 5 years post-banding for females).

POPULATION PARAMETERS: Sex ratios varied from parity for immatures to female-biased for adults. Estimated annual survivorship for this population was estimated to be 29.4% for males and 44.6% for females. Sexual differences in survivorship and female-biased adult sex ratios were thought to be a result of capture bias towards females and higher mortality of males (Mulvihill and Leberman 1992). Known maximum age is 5 years for males and 9 years for females (Robinson et al. 1996).

Egg-laying dates range from late March through early September; earliest clutches are laid in the deep south, the latest in the north. Clutch size is nearly always two, but clutches of one or three eggs have been reported. Eggs are laid 1-3 days apart; incubation begins after the first egg is laid. Incubation, by the female only, lasts 12-17 days. Hatching is asynchronous, 1-3 days apart. Brooding and feeding of young is by the female only. Young fledge in 18-22 days. Individual females often produce two or sometimes three broods per year (Bent 1940; Robinson et al. 1996; Terres 1991; R. Sargent, pers. comm.).