Media & Education
BATS Magazine

June 2010, Volume 8, Issue 6

Bats & Hummingbird Feeders

Southern Arizona residents have noticed for years that their hummingbird feeders were being drained during summer nights, when hummingbirds are supposed to be sleeping. The culprits, only occasionally spotted by their human benefactors, are bats. And that leads to an intriguing citizen-science project.

Almost all of the 46 bat species in the United States eat insects, but three species feed on nectar from flowers of desert cacti and agave, plants that depend on bats for pollination. Two of these pollinators are found in southern Arizona, where they are increasingly adding backyard hummingbird feeders to their foraging routine.

The lesser long-nosed bat is listed as endangered in both the U.S. and Mexico, while the Mexican long-tongued bat is an Arizona species of concern. Both spend their winters in Mexico, then migrate into Arizona for the summer.

Increasing numbers of bats are being reported at hummingbird feeders in and around Tucson and across a broad swatch of southern Arizona. This sounded to wildlife managers and biologists like an excellent research and monitoring opportunity. Since 2006, a growing crew of volunteer monitors has been documenting bats’ use of their backyard hummingbird feeders. Their reports provide important information on when bats arrive and leave the area and, combined with other data, help scientists identify roosts, foraging behavior and migratory corridors.

It also provides critical information for bat-conservation planning, especially in urban areas such as Tucson.

Data collection is managed by Biologist Ted Fleming of the University of Arizona. The citizen-science project is spearheaded by the City of Tucson and the Town of Marana. Partners in this innovative program include Bat Conservation International, the U.S. Fish and Wildlife Service and the Arizona Game and Fish Department.

Volunteers need only monitor their hummingbird feeders two or three times a week through the summer, measuring the level of fluid in the feeder just before dark and again in the morning. Your results can be reported online or on data-sheets submitted in the fall, after the bats have left.
For more information on this program, please visit

For more information on this program, please visit

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