Calypte costae

Howell and Webb (1995) merged Calypte in Archilochus (AOU 1983).

Fairly large range in southwestern North America; large population size; trend uncertain but overall probably relatively stable; locally threatened by habitat loss and alteration from human activities and exotic plants, but most of habitat remains intact.

Breeding range extends from central California (north to Monterey, Stanislaus, and Inyo counties), southern Nevada, and southwestern Utah south to southern Baja California (including the Channel Islands off California, and islands off the coast of Baja California), Sonora (including Tiburon and San Esteban islands), southern Arizona, and (probably) southwestern New Mexico; there is an isolated breeding attempt (eggs laid, nest destroyed) for southern Oregon (AOU 1998). Winter range extends from southern California and southern Arizona south to Sinaloa and Nayarit, casually north to southwestern British Columbia, Oregon, and central Nevada, and east to central and southern Texas (Hays and Kleberg counties) (AOU 1998).

The number of distinct occurrences or subpopulations has not been determined using standardized criteria, but this species is represented by a large number of observation/collection sites (e.g., see GBIF database, eBird) and locations (as defined by IUCN).

The California coastal scrub habitat used by this species has been nearly eliminated in the United States (but much remains in Baja Califronia), and the species' desert scrub habitat faces local threats from urban, residential, and agricultural development and from flood control (Baltosser and Scott 1996). On the other hand, desert scrub habitat is extensive and remains largely intact. In southern California, the species has shown some adaptability to agricultural and urban development (e.g., use of feeders and exotic plants), sometimes breeding in orchards and breeding and wintering in coastal suburbs (see Baltosser and Scott 1996). Urban habitats appear to be not commonly used in regions dominated by desert scrub (see Baltosser and Scott 1996).

The most serious threat may be clearing of desert scrub, thorn forest, and tropical deciduous forest for planting South African buffelgrass (Cenchrus ciliaris [Pennisetum ciliare]) for cattle forage, primarily in Sonora. This drought-resistant grass is fire-prone, and by fueling repeated fires, can eliminate native plants that are not fire-adapted (especially cacti and trees) (see Baltosser and Scott 1996 for further documentation).

In Baja California and Sonora, cattle-grazing in desert, thorn scrub, and Cape deciduous forest is often intensive, and livestock grazing commonly occurs in desert scrub habitats on public lands in Arizona and California. Indirect effects of livestock grazing on hummingbirds are unknown. Some nectar plants (e.g., palo adán and ocotillo) resist grazing when mature, but shrub seedlings and herbs may be affected. However, traditional grazing in native habitat is a minor problem compared to buffelgrass conversion (Baltosser and Scott 1996).

In California chaparral, Costa’s Hummingbird apparently thrives in recently burned areas and probably benefits from a frequent-fire regime. In contrast, frequent fires are unnatural in desert scrub, and thus burning is of concern because many tree species used for nesting are not fire-adapted (Baltosser and Scott 1996).