Tiny Costa’s Hummingbird—named for early hummingbird collector Louis Costa—is among the smallest of U.S. breeding birds. Found in hot, dry habitats like the Sonoran and Mojave deserts, the species is an important pollinator of desert plants and cacti, particularly red penstemon.
The birds migrate and nest in February or March, when desert flowers are most abundant and heat has not yet peaked. They wander if resources become scarce or temperatures climb too high. But unlike Rufous, Ruby-throated, and Calliope Hummingbirds, Costa’s are short-distance migrants, moving only as far south as northern Mexico in winter.
(Video © Don DesJardin, 2014)
Hummingbirds have high energy needs and unlike most other birds, lack insulating down feathers. To survive cold temperatures, the birds can enter a state of torpor, lowering internal thermostats to reduce body temperature and slow heart rate. In the case of Costa’s Hummingbird, this can mean reducing the heart rate from a normal daytime rate of 500-900 beats per minute down to 50.
Urbanization, agriculture, and competition from Anna’s Hummingbird are edging Costa’s from some of its former habitat, especially coastal areas and desert scrub. Introduction of non-native buffelgrass, or African foxtail grass, is another problem. Planted for erosion control and to feed cattle, this plant outcompetes the native flora needed by the birds.
Costa’s Hummingbirds will visit hummingbird feeders and backyards with desert-friendly landscaping that includes native flowers.