Will the data provided by the hummingbird network really contribute to conservation? It's probably too early to tell for sure, but already there are hints at the value of this effort. "In September 2010, the Arizona Daily Star published an article on hummingbirds," says Wethington. "The reporter had interviewed people who were monitoring hummingbirds in the area, particularly in the Huachuca and Santa Rita mountains, and they were saying that hummingbird populations were crashing. But when that reporter got to me, our data was able to tell us that, yes, in 2010 the numbers of birds at feeders were low. We could also see from our data that this was likely part of the cycle of variability in hummingbird populations, because hummingbird numbers were low in 2005, and then rebounded from 2006 to 2009." Still, Wethington has no idea whether hummingbird populations will rebound this time. It'll take many years of collecting data, and many more monitoring sites, some of them likely covering much larger areas.
In the meantime, other scientists are beginning to tap into the network. Holly Ernest, a tall woman with short dark hair and a bright smile, is a professor in wildlife population health and ecological genetics at University of California at Davis. In Ernest's Wildlife and Ecological Genetics Lab, she and her graduate students apply DNA analysis and conservation ecology to the study of wild birds and mammals. Ernest became interested in hummingbirds in 2006, when she volunteered at a banding station at the McLaughlin Natural Reserve near Clear Lake, Calif. "I was just going to do it as a volunteer, to get out of the office and to learn a new skill," Ernest says. "And then, once I started, I saw all kinds of research questions that hadn't been addressed, and I was really excited, especially because some of the questions applied to my own work."
One of her lab's main interests is wildlife disease. Ernest noticed crusty, wart-like nodules appearing on the feet and legs and around the eyes and the base of the bill of one species in particular -- the Anna's hummingbird. She wondered if the birds had a disease called avian pox, or whether it was something else. She began collecting specimens of the crusts, which often fall off afflicted birds when they're handled, and in 2010, enlisted HMN volunteers to send crusts and feathers to her lab. Now, the researchers are developing the laboratory tools to analyze the samples.
Ernest's lab is also studying population genetics, using genetic material to identify individuals and populations. HMN citizen scientists, following the protocol developed by Ernest, provide her lab with feathers from which DNA is extracted. The information gleaned will help the researchers understand the structure and genetic diversity of entire populations and species of hummingbirds.
Feathers collected by volunteers are also being used by another scientist, Jonathan Moran, an assistant professor in the School of Environment and Sustainability at Royal Roads University in British Columbia. He's measuring the amount of deuterium -- a naturally occurring stable hydrogen isotope -- in the feathers to help track down the nesting and wintering areas of rufous hummingbirds. Deuterium concentrations are found in a predictable gradient across the globe associated with latitude. Plants take up the isotope from precipitation, and then hummingbirds absorb it from the nectar they imbibe and the insects that they eat. When the birds grow new feathers after hatching or molting, the feathers reflect the deuterium concentration of the foods the birds ate and thus the latitude at which those feathers grew. So, because hummingbirds molt in the winter, the feathers collected on their northbound migration will, theoretically, reveal the latitude of their wintering grounds at the southern end of their range. Moran discovered that male and female rufous hummingbirds appear to winter in the mountains around Guadalajara, Mexico, but in different areas. More research is needed to pinpoint exact locations, he says, but the results suggest that protecting rufous hummingbirds in their wintering grounds means identifying the places that harbor each sex.
The hummingbird network has expanded over time and now monitors some sites managed by federal agencies. In the spring of 2009, Lisa Young, a biologist for the Dixie National Forest in Utah, noticed that an unusual number of hummingbirds were coming through the rugged plateaus and deep canyons of the Grand Staircase-Escalante National Monument. She contacted Wethington; they worked with Sarah Haas and Terry Tolbert, one of the monument's wildlife biologists, to add three new sites to the hummingbird network -- one in a riparian area inside the national monument at 5,400 feet above sea level; another in the desert scrub at the Escalante Visitor Center, at 6,000 feet; and a third at 8,000 feet in Bryce Canyon's ponderosa pine forest. Interagency cooperation has provided benefits beyond the institutional support. "We're able to spread out the effort and look at different areas," says Haas. "Then we can look for patterns over a much larger region."
Hummingbird researchers are especially intrigued by landscape patterns, particularly the locations of the nectar plants the birds rely on. Biologists collect and identify the pollen of flowering plants in monitoring areas. By comparing pollen samples taken from the heads and beaks of hummingbirds with the pollen of various plants, they can identify the species on which the hummingbirds rely.
Young and her group also hope that hummingbirds can shed some light on how climate change might affect ecological systems. How, for example, will a warming climate affect the flowering time of nectar plants? How will that affect hummingbird migration and survival, and what can it tell us about other species with similar habitat needs? Ultimately, the information gathered could help public-land managers make more informed decisions. Hummingbirds rely on dense growths of shrubs, saplings and flowering plants, which typically emerge after wildfires. Post-burn logging or tree planting can reduce the diversity of this early successional vegetation. With knowledge gained from hummingbird monitoring, land managers may decide to forgo post-burn logging in important habitat, or at least include nectar-bearing plants in their restoration seed mix.
Recently, efforts to develop hummingbird conservation programs have gained momentum. In April 2009, scientists, land managers and nonprofit organizations, led by the U.S. Forest Service and the hummingbird network, convened in Tucson, Ariz., to discuss the conservation needs of North American hummingbirds. The meeting led to the formation of the Western Hummingbird Partnership. The organization has two main goals: to discover what hummingbirds need to successfully reproduce and survive, and to communicate those findings so that habitats can be managed in ways that support thriving hummingbird communities. Member organizations now include HMN, the U.S. Forest Service's Wings Across America program, Klamath Bird Observatory, Point Reyes Bird Observatory Conservation Science, Rocky Mountain Bird Observatory, and several universities in Canada and Mexico.
The Western Hummingbird Partnership works to coordinate its members' conservation and research activities, so that results are shared and work isn't needlessly duplicated. "What we recognized was that, although many people were conducting their breeding bird survey routes ... or some other form of monitoring at the local level, the data wasn't being compiled or assessed uniquely for hummingbirds," says Cheryl Carrothers, a co-founder and wildlife program leader for the Forest Service in Alaska. "That information was just falling through the cracks." Early projects conducted by the partnership include studies of the distribution and abundance of nectar plants on pre- and post-fire landscapes and the effects of wildfire on hummingbird communities.