as Oaxaca. L. c. basophils is found in southeastern Arizona, southern New Mexico, and in the northwestern Mexican states of Sonora, Chihuahua, and Durango. L. c. phasmorus is positively known only from the Chisos Mountains of southern Texas, where it breeds, but its non-breeding range is not known. Birds in the northern Mexican state of Nuevo León may also be this subspecies rather than the nominate. The blue-throated mountain gem is found in a variety of moist forest landscapes. In the US and northern Mexico, it occurs in riparian forest (often in canyons), pine-oak forest, and mixed coniferous forests. In central and southern Mexico it tends to favor coniferous forests. In Arizona it is found in the "sky island" mountain ranges, seldom below of elevation. Near Mexico City it occurs between and in Oaxaca between . Behavior Movement The two northern subspecies of blue-throated mountaingem, and possibly the northernmost of the nominate subspecies, migrate south in winter, but their exact locations are not known. A few individuals remain through winter at feeding stations in southeastern Arizona. The populations in central and southern Mexico are thought to withdraw to lower elevations in winter but this movement has not been fully defined. Feeding The blue-throated mountaingem forages for nectar at a wide variety of flowering plants. The species fed from vary considerably across the bird's wide north–south and elevational ranges. It is common at sugar-water feeders. It hovers to feed on nectar. In some areas it defends patches of large flowers but not those of smaller ones. In the breeding season (especially early when flowers are scarce) and in winter it also feeds on small arthropods. These are taken by hawking, in sustained flight, and by gleaning from bark and foliage. In winter it also feeds on sap from wells created by the Red-naped sapsucker (Syraphicus nuchalis). Breeding The blue-throated mountaingem's breeding seasons vary throughout its range. It begins in February in Veracruz, Mexico, and continues to September in some parts of its range. The earliest known egg laying in Arizona was in mid-Apr. In the higher elevations in Mexico laying begins in late May or June. Two clutches per season are common and sometimes three have been documented. As with all hummingbirds, the female alone constructs the nest and raises the young. The nest is made from soft plant fibers cemented with spider silk. The exterior is camouflaged with green mosses