NPS/Jean Palumbo, Southern Colorado Plateau Network

Sarah Haas, wildlife biologist for Bryce Canyon National Park, observes while Adam Hutchins, Dixie National Forest wildlife technician, bands a hummingbird.

Hummingbirds have one of the highest metabolic rates of any animal (Hargrove 2005). When you consider their small size and the long migrations of many species, hummingbirds quite possibly could serve as an early indicator of the cascading effects of a warming climate in the western United States. When the timing of flowering for nectar-producing plants does not coincide with their daily energy needs, hummingbird populations may decline. And since hummingbirds are pollinators, a decline in their numbers could cause a decline in fruit production for the plants they pollinate (Allen-Wardell 1998). This, in turn, may adversely affect populations of organisms that feed on fruit, such as other bird and animal species, including invertebrates and microbes.

“It’s all about phenology,” says Larry Norris, NPS southwest research coordinator for the Desert Southwest Cooperative Ecosystem Studies Unit (CESU). “When do the plants that hummingbirds feed on bloom? When do the midges and gnats that they eat hatch?” To discover how phenology—the timing of periodic biological phenomena—affects hummingbirds, the CESU provided funding in 2003 that was critical in establishing the Hummingbird Monitoring Network (HMN), which is run by executive director Susan Wethington and headquartered in Patagonia, Arizona. This helped to start up monitoring sites in Arizona’s Chiricahua National Monument, Coronado National Memorial, and Tumacacori National Historical Park, and marked the beginning of hummingbird monitoring on the Colorado Plateau.