Selasphorus rufus

Breeding habitat includes coniferous forest, second growth, thickets, and brushy hillsides, with foraging extending into adjacent scrubby areas and meadows with abundant nectar flowers (AOU 1998); habitat is chiefly secondary succession communities and forest openings (Calder 1993, Healy and Calder 2006). On national forest lands in northern Idaho and western Montana, this species was most commonly detected on clearcut and seed-tree harvest units and in post-fire habitats; also riparian shrub, cedar-hemlock, and spruce-fir habitats (Hutto 1995). It had a higher probability of detection in cut rather than uncut forests (Hutto and Young 1999).

Rufous hummingbirds also are associated with old-growth coniferous forest stands (e.g., Carey et al. 1991, Gilbert and Allwine 1991, Manuwal 1991, Hejl and Paige 1993), where suitable food resources develop in tree-fall gaps and other natural openings and edges (Carey et al. 1991, Gilbert and Allwine 1991, Manuwal 1991, Hejl and Paige 1993). In western Oregon, rufous hummingbirds nested in 16-120 year-old second-growth and older than 120 year-old mature forest (Meslow and Wight 1975). In northern Idaho cedar-hemlock, they were significantly more abundant in selectively harvested and old-growth stands than in old-growth stands recently fragmented by clearcuts (Hejl and Paige 1993). In Oregon Cascades Douglas-fir forests, rufous hummingbirds were positively associated with stand age where old-growth stands included numerous small openings, and they were found in stands with large to very large western hemlocks (Gilbert and Allwine 1991). In two Washington Cascades studies, occurrence in old-growth (200-700 years old) was double or nearly double that in young (40-80 years) or mature (80-190 years) forest stands (Carey et al. 1991; Manuwal 1991). Old-growth stands showed greater spatial diversity and midstory cover, and lower canopy cover (Carey et al. 1991). Abundance was higher in mesic and dry old-growth Douglas-fir stands than in wet stands (Manuwal 1991).

Nests are placed in trees, shrubs, or vines, about 1-15 meters (usually less than 5 meters) above ground (e.g., in blackberry bush, huckleberry bush, overhanging vine, alder, drooping branch of conifer, among roots of fallen tree, crown of deciduous tree; Johnsgard 1983). Baltosser (1989) observed that areas with both greater quantities and more predictable nectar supplies supported more hummingbird nests; this pattern may also apply to rufous hummingbird.

Habitat in migration and winter includes open situations where flowers are present (AOU 1998). During southward migration, this species uses mountain meadows and disturbed habitats with Castilleja spp, Aquilegia formosa, Epilobium angustifolium, Delphinium spp. Penstemon barbatus, Monarda menthaefolia, Linaria vulgaris, and Cleome serrulata (Calder 1993). In Mexico, it occurs in pine woods with abundant flowers and flowering shrubs; in open country with scattered trees and shrubs; suburban gardens, parks, vacant lots (Edwards 1972). Nonbreeding habitat also includes oak forests interspersed with pine and juniper between 2,300-3,000 meters; higher oak-fir forests; shrubby secondary succession habitats; arid thorn forest; brush at farm and roadside edges with Salvia spp.; scrublands and disturbed oak woodland (Calder 1993).

This hummingbird actively defends feeding and nesting territory both inter- and intraspecifically (Cody 1968; Baltosser 1989; Calder 1993). Banding returns show the species has strong fidelity to breeding sites, wintering sites, and migration routes (Calder and Jones 1989; Calder 1993); it has been shown to have strong spatial memory for nectar sites (Hurly 1996). Rufous hummingbirds establish and defend territories around nectar sources on breeding sites, migration stopovers, and wintering sites. Migrating birds can gain an average mass of 0.23 g per day, and conserve energy by going into torpor at night (Hixon and Carpenter 1988). Feeding territory size depends on flower density and fluctuates with the rate of weight gain possible from nectar availability and the cost of territorial defense (Kodric-Brown and Brown 1978; Gass 1979; Carpenter et al. 1983). Feeding territory sizes range from 32 to 3,300 square meters (Gass 1979; Kodric-Brown and Brown 1978). Calder (1993) notes that banded birds have been recaptured at feeders 2 kilometers apart in summer.

Breeding densities reported range from 0.17 to 2.6 nests per hectare (Horvath 1964 cited in Calder 1993). In Oregon Coast Range Douglas-fir forests, densities reported at 0.16 birds per hectare in young stands, 0.13 birds per hectare mature stands, and 0.33 birds per hectare in old-growth stands (Carey et al. 1991). Average relative abundances reported on BBS routes range from 0.83 to 4.94 birds per 25-mile survey route (Sauer et al. 1997). In winter, 95 individuals captured in 12 nets over two days in a pine-oak post-fire succession habitat in Sierra de Manantlan Biosphere Reserve, Jalisco, Mexico (Calder 1993).

Baltosser (1983, cited in Miller and Gass 1985) reported high egg and nestling predation (25 percent to 58 percent) in four species of hummingbirds; however, nest predation is apparently unstudied in rufous hummingbirds. Predation on adult hummingbirds is not likely to play a large role in adult mortality (Miller and Gass 1985; Calder 1993).

Some observers suggest that artificial feeders may increase populations above natural levels by providing food beyond flowering seasons (see Calder 1993) or encouraging birds to delay migration past availability of natural foods. Feeders may also subject birds to predation, disease, or collision with windows. However none of these factors are fully studied or quantified (Calder 1993).

Clutch size is two. Young are capable of first flight about 20 days after hatching (Terres 1980). Bent (1940) reported of instance of as many as 20 nests only a few yards apart in second-growth. Individuals may re-use a nest in subsequent years (Bent 1940, Calder 1993).