Weighing less than a nickel, hummingbirds may be among the most common backyard visitors along the Pacific Coast from Canada to Mexico, but surprisingly little is known about their population dynamics, disease ecology or genetics. That’s where expertise from wildlife veterinarians and involvement of citizen scientists come in.
Since 2010, Dr. Holly Ernest—wildlife veterinarian, geneticist, and a professor in the School of Veterinary Medicine’s Department of Population Health and Reproduction and Veterinary Genetics Laboratory—has run the Hummingbird Health and Genetic Diversity Project. Primary goals of this research are to determine levels of health and disease, evaluate migration ecology, and assess genetic diversity over large expanses of habitats (landscape ecology and genetics). The project focuses on hummingbird species that breed or migrate through California: Anna’s, Costa’s, Allen’s, Rufous, Black-chinned, Calliope, and Broad-tailed hummingbirds.
Ernest is a federally permitted Master bird bander, one of fewer than about 150 in the country specializing in hummingbirds. For field components of the research she coordinates a group of dedicated volunteers including retirees, undergraduate and graduate students, and faculty members to gather data on this poorly understood avian family.
Volunteers gather long before sunrise to set net traps over nectar feeders in a variety of gardens. When a hummingbird comes to feed, the net drops and a trained volunteer is able to carefully remove the tiny bird from the trap and bird banders record measurements like weight, bill and wing length, body fat, disease and molt stage. Because the birds need to eat every 20 to 30 minutes, the veterinarian-bander feeds the birds after recording all the data. Each bird is fitted with an identification band so that if it is recaptured, the new measurements can be compared against previous data. Banders need a federal permit, training—and patience!
“They are so little, but we can learn so much from hummingbirds as indicators of landscape, climate and environmental change based on the way they eat, where they travel and their sensitivity to pesticides,” said Dr. Loreto Godoy*, a PhD candidate in Ernest’s lab who is focusing her research on Anna’s hummingbirds. “Hummers are great pollinators and provide valuable ecosystem services.”
Traditionally, Anna’s hummingbirds have been observed migrating great distances, but Godoy said their distribution since the 1930s has changed a great deal due to adaptability. They’ve followed human changes as more people plant exotic flowers in their gardens and put up feeders.
Thanks to data from banding studies conducted by Ernest and other Master bird banders, as well as contributions from wildlife rehabilitation hospitals, Godoy has recently discovered a previously unidentified avian pox in Anna’s hummingbirds. It isn’t clear yet whether this is a new or pre-existing disease and researchers are just now collecting data through banding studies. She’s working to characterize the risk factors for this particular disease and to determine the impact of avian pox in this species. The research paper by Godoy, Ernest, avian health expert Dr. Lisa Tell, wildlife pathologist Dr. Leslie Woods, and collaborators is in press with the Journal of Wildlife Diseases.
“In other birds, this disease may not always be fatal, but we don’t have a lot of recapture data to assess rates of illness and death for hummingbirds,” Godoy said. “In other species, the pox results in behavior changes that lead to breeding problems, distress calls, and predation because they can’t feed or fly as well.”
Tracking the little fliers is a challenge because they can’t be fitted with a GPS collar like mountain lions and radio transmitters are not quite small enough for practical use in hummingbirds. Ernest, whose lab covers a wide variety of wildlife research projects, says banding provides one of the key tools for gathering the scientific data that will provide novel health and ecology information about hummingbirds.
“Banding is a great way to teach people about wildlife health and research, and brings science close to home,” Ernest said. “We excited about involving the public in wildlife research and also about what we hope to learn as a result of this collaboration.”
This effort relies on partnerships between Ernest’s Hummingbird Project and the UC Nature Reserves, the UC Davis Wildlife Museum, wildlife rehabilitation hospitals, members of the public who allow access to land and gardens, the Hummingbird Monitoring Network, state and federal agencies, Audubon Societies, including Yolo Audubon and Sacramento Audubon, as well as others. Dr. Ernest secured grants from US Fish and Wildlife, the Western Hummingbird Partnership, a UC Davis Academic Senate Grant, and non-profits to support this work.
* Sadly, Loreto Godoy passed away on June 26, 2013. (Story here.) She is fondly remembered by all who knew her.
Trina Wood, Communications