Seabirds make choices, revealing Puget Sound’s health

Dec. 15–DABOB BAY — Sunlight glinted off the water, as the 24-foot research boat headed out of Dabob Bay on a cold November day. Dressed for winter, two expert observers scanned the Hood Canal waters for seabirds, one looking left, the other right.

“Double-crested cormorant, one, flying at 112,” called out Corey VanStratt, his voice heard clearly over headphones worn by each member of this research team for the Washington Department of Fish and Wildlife.

“Common loon flushed at 100,” said Kathy Gunther a moment later.

“Four double-crested cormorants flushed, four on the water, at 503,” Gunther quickly added.

All the while, Amy Baker, another expert observer for the agency, used a computer to keep track of their observations, listing species, behavior and distance (in meters).

Then came a payoff observation — one of several that cold day — when Gunther reported, “Marbled murrelet, two on water, plumage class 6, 60 meters out.”

Finding marbled murrelets was rewarding for the research team, because the Navy-funded project is designed to figure out where the birds go in winter — a time when they are dressed in their striking black-and-white plumage.

Marbled murrelets were listed as “threatened” under the Endangered Species Act in 1992. Since 2001, their numbers have dropped by more than 4 percent per year in Washington state, according to results from spring and summer boat surveys.

For nearly 200 years, the nesting habits of this robin-sized seabird remained one of the great mysteries of ornithology. Today, the marbled murrelet is known to be an odd bird, not well suited to long-term survival in today’s changing world.

In the spring, the female lays a single egg on a moss-covered branch in a large, old-growth tree. She and her mate take turns tending the nest and flying as much as 50 miles to the sea to catch fish for their lone chick. The adults typically make this trip at dawn and dusk for about a month, until their chick is ready to fly.

Why these birds have evolved such strange behavior remains a mystery, although old-growth trees used to be found next to the water. Other members of the auk family, to which they belong, generally live in colonies, often in burrows, and not in trees at all.

The seabirds of Puget Sound — more than 70 common species — are truly a diverse group. They come in all sizes, from marbled murrelets to great blue herons. Some live in Puget Sound all year round; some fly to the northern Arctic for breeding; and others just stop over in the spring and fall on their long migration between Canada and Mexico.

The wintering population of seabirds in Puget Sound grows to about four times the summer population, reaching a peak of perhaps 500,000 birds, based on a rough extrapolation from ongoing surveys.

Situated at the top of Puget Sound’s complex food web, marine birds form a rich tapestry of nature. Because they can fly from one place to another, birds are making choices all the time about where to go, especially in winter when they’re not tied to a nest.

“Marine birds serve as pretty good indicators for the health of Puget Sound,” said Jerry Joyce, co-chairman of a task force on birds that developed new “vitals signs” indicators for the Puget Sound Partnership. “They’re almost a direct measure of the health of the food web.”

KNOWING THE BIRDS

Because they are able to make choices, seabirds might be viewed as scouts for the health of the ecosystem. If all the birds that came and went could be tracked by humans, their presence or absence would tell us that something is going right — or wrong — with the quality of habitat in a specific area. But, despite several new and ongoing surveys, keeping track of birds remains a real challenge.

“We actually know remarkably little about the status and trends of many species,” said Peter Hodum, a seabird researcher at the University of Puget Sound. “That is slowly changing. But, aside from monitoring, there’s still not a lot being done on the ecology. As a taxonomic group, broadly speaking, they are still not well studied or understood in the Salish Sea region.”

Even for birds that live year-round in Puget Sound, questions are numerous. For example, steep declines have been seen in the number of tufted puffins, once common throughout Puget Sound, according to studies by Hodum and Scott Pearson, a bird specialist with the state Department of Fish and Wildlife. Tufted puffins are now being suggested for “threatened” or “endangered” status under federal and state laws.

On Tatoosh Island in the northwestern corner of the state, the researchers were able to get closer to the problems facing puffins. They showed that nesting burrows were highly occupied by puffin parents, yet the rate of hatching was low and the number of offspring living long enough to fly was lower still.

At the same time, rhinoceros auklets, a burrowing species related to puffins, showed high levels of hatching and fledging success, and their populations are on the increase.

“Why is one doing well and one doing poorly?” Hodum asked. “Something is driving this on a very big scale.”

Lots of ideas are floating around, he said. Tufted puffins are known to be disturbed easily. Factors might include increasing numbers of predators — including protected bald eagles and peregrine falcons.

Unlike tufted puffins, Hodum said, “rhinoceros auklets come back to the colonies at night rather than during the day. Also, by nature, they are less vulnerable to disturbance and predation.”

Perhaps the rhinoceros auklets have switched to a more abundant prey or to a variety of prey species, whereas the tufted puffins are holding out for fish species in decline.

On Protection Island, which contains one of the largest rhinoceros auklet colonies in the world, the number of active burrows has doubled in recent years. Located near Port Townsend, Protection Island is managed as a refuge by the U.S. Fish and Wildlife Service.

MIGRATION FACTORS

Birds that nest in Canada or Alaska and spend their winters in Puget Sound have their own stories to tell. Because they have a choice, large numbers of wintering birds would suggest that things are going well.

“During non-nesting seasons, the birds can go to where the food is,” said Pearson of Fish and Wildlife. “If we have a lot of herring in Puget Sound this year, we might get a bunch of Canadian birds coming down.”

But low numbers of birds cannot be so easily blamed on poor conditions in Puget Sound, he noted. Scoters, for example, breed in the high Arctic, more than 2,000 miles away. If the birds don’t show up in Puget Sound, one must first find out how the birds fared through the summer and whether reproduction was high. Then one can try to figure out where they went.

“I try to think at a broader scale,” Pearson said. “What is happening in other places?”

For the birds to fly great distances, they must find food when they arrive in Puget Sound, a place once extraordinarily rich in herring and other forage fish. If the birds are willing to fly even farther than Puget Sound, then something must be wrong.

That could be the story with western grebes, an elegant black-and-white bird, which migrates to Canadian lakes in summer. Once common in Puget Sound during the winter, western grebes appear to have declined by 95 percent since the 1970s. At the same time, populations have increased by 300 percent along the California coast, where previous numbers were small.

Overall, it appears the total population of western grebes in this region declined by about 50 percent over 35 years, and some researchers believe human disturbance in their nesting areas could be part of the problem.

For whatever reason, the birds are making a choice, one that has not been fully successful, given their overall population decline. We know that Puget Sound herring stocks are down from historical levels, while Pacific sardines have shown a dramatic increase off the California coast. Researchers are working to connect the dots between these various issues.

MARBLED MURRELET

Because the marbled murrelet generally lays one egg on a large, moss-covered branch, the little seabird provides one more reason to protect old-growth forests. In fact, efforts to save the marbled murrelet from extinction have placed the bird at the center of ongoing legal battles over timber harvesting in Washington state.

In some ways, the murrelet has even replaced the spotted owl as the species frequently named in lawsuits when trying to protect old growth from clear-cuts. That’s because the murrelets are directly dependent on large trees in forested areas, whereas owls depend on old-growth forests for their food.

The summer boat surveys by the Washington Department of Fish and Wildlife are funded by the U.S. Fish and Wildlife Service, which wants to know whether logging restrictions and other protections are aiding the murrelet on the Olympic Peninsula. The boat follows a defined course each time it goes out, so results can be compared.

Likewise, the Navy has contributed to the murrelet surveys, which also compile data about all seabird and marine mammal encounters. Because the marbled murrelet is a threatened species, the Navy must reassure other federal agencies that its military operations will not endanger the long-term recovery of the species.

Cindi Kunz, wildlife biologist for Naval Facilities Engineering Command, said she can’t help but be fascinated by the marbled murrelet, given its mysterious past. In the late 1700s, early explorers first identified the species swimming on the water. But nobody found a nest until 1974, when a professional tree pruner nearly stepped on a baby bird with webbed feet while cutting limbs nearly 150 feet up a Douglas fir tree. The discovery, by tree climber Hoyt Foster, came about in California’s Basin Redwoods State Park.

“I love that bird,” Kunz said recently as she recalled the history of the murrelet. She noted that the Navy is proud to protect a stand of old-growth trees at its 4,700-acre Jim Creek Radio Station northwest of Marysville in Snohomish County. It’s one of the last old-growth stands in that area. The station is close enough to Puget Sound to provide nesting habitat for the marbled murrelet, and biologists have observed the birds flying to and from the area.

Last year, the Navy honored Kunz with an award for natural resources protection after she coordinated a panel of experts who were asked to establish a sound level for pile-driving that would not harm marbled murrelets during construction projects. It was a complex problem, requiring the expertise of underwater acoustic experts from government agencies and universities.

“It was through her leadership of the panel that Kunz advanced the understanding of the marbled murrelets’ biology (and) physiology and enhanced the U.S. Fish and Wildlife Services’ ability to manage and conserve the species,” according to the Navy commendation.

In 2010, the marbled murrelet population throughout Puget Sound was estimated at 4,393 birds. For the Washington coast, the estimate was 1,286 birds. For both areas, the population appeared to be declining more than 7 percent.

Populations of other seabirds have been estimated from aerial surveys by the Puget Sound Ecosystem Monitoring Program, as well as volunteer efforts, including the Puget Sound Seabird Survey, or PSSS.

PSSS, coordinated by Seattle Audubon, involves nearly 100 experienced amateur and professional birders who work in teams and volunteer their time. In all, they identify birds at up to 84 sites throughout the main basin of Puget Sound. Last summer, another 26 sites were added along the Strait of Juan de Fuca and across Whidbey Island. The surveys occur on the first Saturday of each month.

“You would not be able to get 100 scientists surveying 80 sites one day each month for eight months (a year),” said Toby Ross, science manager for Seattle Audubon who coordinates the survey. “It would cost a huge amount of money.”

Because of the abilities of the participants and the scientific methodology they use, results of the volunteer bird counts can be used to help estimate overall bird populations, according to Pearson of Fish and Wildlife.

“This is incredibly well-designed for what people call ‘citizen science,'” he said. “I believe it will provide a very valuable piece of information.”

Results from seven years of observations are expected early next year.

ECOSYSTEM INDICATORS

Meanwhile, how to interpret and respond to the limited, but growing, findings about bird populations is under consideration by scientists advising the Puget Sound Partnership.

“These systems are very complex and our attempts at understanding them are, at best, incomplete,” said Hodum of the University of Puget Sound. “How do we do conservation planning and take meaningful action in the face of uncertainty?”

Puget Sound Partnership already is taking steps to protect and restore shorelines, including eelgrass beds, and to improve water quality, but people want to see results, said Nathalie Hamel, monitoring program analyst for the partnership.

“The public demands it,” she said. “We are investing a lot of money into recovering Puget Sound, and the first question that comes up is, ‘Is it making a difference?'”

As restoration continues, it becomes more important than ever to measure the changes and begin to understand how helping one species helps a variety of others.

“I’m hopeful,” Hamel said. “I think we are getting recognition from our leaders that this data-gathering is important and that without it we cannot show … the outcome of our recovery efforts.”

Hamel co-chaired a scientific panel that proposed new ecosystem indicators to measure the changing conditions of Puget Sound seabirds. The group steered away from a single population-based indicator — such as used for herring, salmon and orcas — and chose instead a group of indicators to measure abundance, breeding and diet.

Specifically, the indicators are focused on summer densities of rhinoceros auklets, pigeon guillemots and marbled murrelets, along with winter densities of scoters. Researchers also will assess the amount of fish fed to the chicks of rhinoceros auklets and pigeon guillemots, while measuring the burrow occupancy rate and reproductive success of those two species.

No numerical targets were proposed for the indicators, but trends for each one are to be reported next year.