Editor’s note: This article first appeared online Jan. 30, 2019
In 1999, the first year of the annual Christmas Bird Count (CBC), Vashon Audubon volunteers counted 1,619 Western grebes floating in Quartermaster Harbor.
There were no Western grebes found in Quartermaster Harbor during the most recent CBC held on Dec. 31, 2018.
Western grebes are graceful, gregarious and charismatic marine birds. They are pursuit divers that plunge into dense schools of forage fish to spear herring, sardines and smelt with their long, yellow bills. Large rafts of grebes spend the winter months in protected saltwater harbors and bays. They summer inland, on freshwater lakes, where they lay their eggs on floating nests and carry newborns on their backs. Western grebes mate for life and are celebrated for a synchronized courtship dance that climaxes in a mad dash across the top of the water called rushing. It’s a must-see on YouTube.
Though impressive, the numbers of Western grebes counted in 1999 was significantly lower than previous decades. According to Ed Swan’s book, The Birds of Vashon Island, during the early to mid-1990s up to “8 to 10 percent of the state’s wintering (Western grebe) population stayed in Quartermaster Harbor,” and it was common to count several thousand birds at a time.
The presence of so many of these remarkable birds in the 1980s inspired master birder Dan Willsie to conduct a 12-year study on grebes in Quartermaster Harbor.
“Grebes only fly at night,” he said. “I would go out early in the morning, and it was magical to see thousands of birds filling the harbor as it got light.”
Willsie says he frequently counted more than 4,000 birds per day feeding on schools of silvery Pacific herring in outer Quartermaster Harbor. Willsie’s study convinced the National Audubon Society to designate Quartermaster Harbor an Important Bird Area in 2000, the same year it became part of the Maury Island Aquatic Reserve. Unfortunately, by the time of these designations, our local Western grebes had already begun to disappear.
The 2001 CBC recorded only 248 Western grebes in Quartermaster Harbor. Through most of the rest of the decade, populations fluctuated from year to year but never again rose above 1,000. There was another significant drop in 2009, when only 17 Western grebes appeared on the Quartermaster Harbor CBC.
Recently, they have become even rarer — annual counts in the past five years have tended to be in the low double or single digits. Avid bird photographer Jim Diers has lived on Vashon Island for 10 years and has never photographed a Western grebe.
The Quartermaster Harbor decline is stark, but it’s not just a Vashon phenomenon. “The decline of Western grebes in the Puget Sound region has been dramatic and difficult to witness,” says master birder Sue Trevathan who compiled the Vashon Audubon CBC records from 1999 to 2013.
Master Birder Ezra Parker, who inherited that responsibility notes, “It’s the most dramatic change we’ve seen in any bird population in our records.”
Declines in marine bird populations are often triggered by a drop-off in their food source, in this case, forage fish such as Pacific herring, surf smelt and sand lance. Dr. Tessa Francis, Vashon’s resident forage fish expert and the lead ecosystem ecologist at the Puget Sound Institute confirms a drop in Pacific herring in local waters: “Many sub-stocks of Pacific herring, the most dominant forage fish species, are declining in Puget Sound, including the Quartermaster sub-stock, [which] has been depleted for many years.”
Some other possible causes include pollution, nutrient availability and changes in water temperature. Each one of these factors can affect the delicate food web that ultimately supports marine birds, salmon and orcas.
A 2013 Canadian study analyzing Audubon Christmas Bird Count data from 1975 to 2010 along the entire West Coast may reveal the fate of our Western grebes. It estimates that the entire Western grebe population has declined approximately 50 percent in the past several decades. But while the number of birds in the Salish Sea may have decreased as much as 95 percent, populations have increased more than 300 percent along the California coast, where Pacific sardine stocks have been more reliable and robust in recent years.
Francis explains, “Our Salish Seabirds may be shifting their distribution to take advantage of more abundant prey.”
It’s a phenomenon scientists call regime shift. In other words, it seems our Western grebes didn’t completely disappear, they just moved to a place with better food.
Field Notes Calendar
Saturday, Feb. 2
Land Trust Native Plant Sale
Pick up your pre-ordered plants and shop from a limited selection of bare-root plants and trees.
9 a.m. to 1 p.m. at the Land Trust Building
Saturday, Feb. 9
Vashon Audubon Field Trip
Come birding on the island. Drop in, free and no experience necessary. Bring binoculars and scopes if you have them and wear walking shoes or boots. Children must be accompanied by an adult. Carpools encouraged and can be arranged at Ober Park.
9 to 11 a.m. Meet at Ober Park Park & Ride.
Wednesday, Feb. 13
Forage Fish Survey
Join BeachNET as we conduct forage fish research on island beaches at low tide. These important fish are critical to the recovery of Puget Sound marine birds, salmon and orcas. Surveys last about two hours. No experience necessary. Email firstname.lastname@example.org for meeting locations and more information, or go to vashonnaturecenter.org/beachnet
Thursday, Feb. 28
Land Trust Book Club
“The Secret Knowledge of Water: Discovering the Essence of the American Desert” by Craig Childs. Join us to discuss how Childs’ obsessive quest to find water in American deserts becomes a highly personal odyssey.
6:30 p.m. at the Land Trust Building,10014 SW Bank Road
As barn owl nesting season approaches, watch to see if the owls choose our nest box again. Go to vashonnaturecenter.org/owlcam.
Thursday, March 14
Vashon Audubon Talk, Birds and Climate Change
Teri Anderson, Chapter Network Manager of Audubon Washington addresses some of the impacts of climate change on bird populations.
7 p.m. at the Land Trust Building
Saturday, March 16
KCD Native Plant Sale Pick-up
10 a.m. to 3 p.m. at the Renton Community Center, 1715 Maple Valley Hwy, Renton.