Researchers Turn a Concerned Eye to the Mysterious Marbled Murrelet
Surrounded by a sea of redwood trees reaching heights of over 350 feet, it is easy to underestimate the impact one person can have on the towering ecosystem of northern California's Redwood National and State Parks. But the increased human activity in these parks has had its effect, as visitors leave behind more than just footprints on trails and campgrounds.
Food scraps left behind on campgrounds are influencing the behavior of the parks' birds—in this case, adult male Steller's Jays—in ways that have a significant impact on other species.
“Steller's Jays are attracted to campgrounds for foraging opportunities provided by campground visitors,” says Will Goldenberg, a graduate researcher at Humboldt State University and the coauthor of a new paper on the topic, published this month in The Condor. Steller's Jays are generalists; they thrive in a variety of environments and readily take advantage of new resources. When campers consistently leave food waste behind, generalist species like Steller's Jays learn to hang around those sites.
The real victim of this phenomenon is the Marbled Murrelet, a federally threatened seabird whose eggs are a food source for Steller's Jays. The Marbled Murrelet nests in old-growth forest in California, Oregon, and Washington. Due to loss of old-growth forests, many of the remaining California-dwelling murrelets nest in protected state parks, areas with an abundance of campgrounds. Seabirds are also creatures of habit; they return to the same tree and branch each year to lay a single egg.
Goldenberg is among many scientists and conservationists who are working to understand the plight of the Marbled Murrelet—and find ways to help the bird survive.
A Mysterious Seabird
Since the Marbled Murrelet was federally listed as a threatened species in 1992, its population in the continental United States has dropped from 23,000 to 19,000 individuals. In Washington, for instance, murrelet populations have been steadily declining by 4.6 percent each year for the past decade, a trend that could lead to extinction, says Steve Holmer, ABC's Senior Policy Advisor and Director of the Bird Conservation Alliance.
Scientists still don't know very much about the Marbled Murrelet. The birds nest high in the canopy of 200- or 300-year-old trees. Although it was first identified as a seabird in 1789, the murrelet's inland habitat remained a mystery for many years.
Of all known nesting locations of North American birds, the Marbled Murrelet's is one of the last to have been discovered. The first good description of its tree-nesting habits was from Big Basin Redwoods State Park, Calif., in 1974.
The main cause of the Marbled Murrelet's decline is that young murrelets aren't surviving, fledging, and joining the population, says Kim Nelson, a research wildlife ecologist in the Department of Fisheries and Wildlife at Oregon State University. The chicks are vulnerable, and habitat loss and predation severely threaten their survival.
The Marbled Murrelet plays an important role in both the marine and forested ecosystems. They are important members of the marine food web, and they also fertilize trees and moss in the forest. “Their population health is reflective of the entire ecosystem,” says Rick Golightly, Professor Emeritus in the Department of Wildlife at Humboldt State University. “If we cannot maintain habitat for Marbled Murrelets, what will happen to all the other old-growth dwellers?”
Forty years ago, Steller's Jays were less of a threat to Marbled Murrelets. When California still had thick old-growth forest, jays ventured less frequently into murrelet nesting habitat, preferring the forest edges instead. Now, logging practices have fragmented the forest and created a multitude of edges dangerously close to murrelet nesting sites.
“Jays like edges,” Golightly says. “By building all these edges in, you've got more jays.”
Berry bushes along the edges of the forest attract Steller's Jays. So does food on campgrounds, which draws them closer to murrelet nests. Once Steller's Jays discover the nests and eggs, they remember the location and begin to prey more heavily on Marbled Murrelet eggs.
“Jays are very opportunistic. If they see food, and that food is in the form of an egg, that egg is going to be predated,” Golightly says.
Goldenberg's study involved observing the behavior of 20 adult male Steller's Jays that frequented campgrounds and 10 that did not. Researchers baited the jays with peanuts glued to paper plates and lured them into mist nets.
Then, the scientists banded the birds and fitted them with VHF transmitters, which allowed the researchers to locate and record the location of each of the birds twice a day. Using radio telemetry, Goldenberg and his team of six wildlife technicians also tracked the birds to their nocturnal roost sites.
The researchers found that campground jays perched more and foraged less than non-campground jays, and also grouped closer together—suggesting that food on the campgrounds was able to sustain a large population of Steller's Jays. They also observed that the jays regularly commuted between the campgrounds and their nocturnal roosts.
All in all, the data indicated that increased food availability causes jays to congregate around campgrounds where Marbled Murrelets also nest.
“While our study may only provide baseline information on the space use and behavior of Steller's Jays, we hope that it will help form the foundation of research that is needed to save our remaining Marbled Murrelets,” Goldenberg says.
Demise of Old-growth Forests
For over four decades, from the early 1950s until the mid-1990s, federal forests in the Pacific Northwest and Northern California were heavily logged. Between 1983 and 1990, and again in 1995 and 1996, laws were suspended that protected the Marbled Murrlet's old-growth forest habitat.
“During this era, the federal government cut down about 85 percent of the old-growth forest across California, Washington, and Oregon,” ABC's Holmer says.
Then, in 1991, a federal court halted all federal timber sales across the region to prevent the forests from being overcut even further. But the Marbled Murrelet had already lost the majority of its habitat.
Unsustainable logging practices continue to remove and fragment murrelet habitat today. Almost all of the Marbled Murrelet's remaining nesting habitat in California is in national and state parks, which are peppered with campgrounds. “The only place where these birds are left in California is in these parks,” Golightly says.
The Bureau of Land Management recently proposed a plan that would weaken protection for the Marbled Murrelet under the Northwest Forest Plan. ABC has opposed the proposal and is urging the Obama administration and agencies associated with forest management to protect existing habitat for the Marbled Murrelet and create new habitat by continuing to allow old-growth forest to develop under the Northwest Forest Plan.
Solutions for the Marbled Murrelet
So how do conservationists halt the decline of Northern California's Marbled Murrelet population? “We have a technique that appears to be working and is actually fairly cost-effective,” says Pia Gabriel, who did her Ph.D. work at Humboldt State on Steller's Jays.
In 2010, Golightly and Gabriel began to experiment with training Steller's Jays to avoid eating Marbled Murrelet eggs. In a captive setting, they presented captured Steller's Jays with mimic eggs containing emetic, a substance that induced vomiting in predatory jays. The jays that ate the eggs remembered the experience and avoided murrelet eggs after their release.
Golightly and Gabriel's study was published in 2014 in the Journal of Wildlife Management. Scientists are currently testing this method in field trials to determine if it can be used on a broader scale to deter Steller's Jays from eating the eggs of Marbled Murrelets.
Park personnel, meanwhile, are working to educate and involve the public in restoration of the Marbled Murrelet population. Visitors are encouraged to “keep it crumb clean” around campsites, and park management has installed food lockers and disposal units in campsites in the redwood forests. These measures help keep Steller's Jays and other wildlife away from campgrounds and have the potential to help recover the Marbled Murrelet's population.
Success is hard to predict and conservation efforts are expected to continue for many decades to come. But conservationists, researchers, and park personnel forge on in the name of the threatened forest-dwelling seabird.
“To me, the Marbled Murrelet represents the most intriguing aspect of the natural world, which is how little we as humans really know,” Goldenberg says.
“They are still one of the most mysterious birds in North America, and losing them before they become fully understood would be such a shame.”
Want to help Marbled Murrelets? Contact your members of Congress and the Obama administration and urge them to support the Northwest Forest Plan and increase protections for old-growth forests and Marbled Murrelets. Take action now!
Audrey Goldfarb is American Bird Conservancy's writing/communications intern. She is currently an undergraduate at the University of Rochester, where she is pursuing a bachelor's degree in molecular genetics, with minors in journalism and psychology. Audrey grew up in a home visited by many birds, including Wild Turkeys, Eastern Bluebirds, Rose-breasted Grosbeaks, Northern Flickers, and Great Blue Herons.