Study Finds Substantial Declines in Local Marine Bird Species
by Holly Donovan and John L. Bower
Holly Donovan is a 2004 graduate of Huxley College of the Environment at Western Washington University. Shes a watershed master alumnus with Skagit Conservation District and her field experiences include a salmon spawning survey, amphibian survey and water quality testing.
John Bower teaches field biology, natural history, evolution, environmental issues and folk music performance at Fairhaven College at Western Washi-ngton University. His past research includes acoustic communication and population ecology of bowhead whales, recording a census of wintering bald eagle populations along the Nooksack River, categorizing marbled murrelet vocalizations and studying acoustic interactions in songbirds.
Look at the avifauna of Whatcom County both in order to expand the knowledge of the county and contribute to the understanding of how the world works.1
Terence R. Wahl
On a snowy January morning, a northwestern crow stands in a Drayton Harbor tideland pecking at the head of a dead ruddy duck. The snow and cold, unusual for our region, makes the harbor more reminiscent of the Maine coastline than northwestern Washington. Our three-person marine bird census team shivers in the cold, as we begin our attempt to count every one of the thousands of birds in the harbor. Weve made this trip seventeen times since March of 2003 and will have done it six more times between now and June 2005 before our work is complete.
We, and others involved in the project, have made many similar census trips all along the shoreline from Tsawwassen, British Columbia and Point Roberts to the north, to Whidbey Island in the south, to San Juan Island in the west. In addition, weve counted marine birds while aboard Washington state and British Columbia ferries enroute to Vancouver Island as well as the Keystone ferry from Whidbey Island to Port Townsend. These counts, primarily conducted by Western Washington University undergraduates, are a part of a study directed by Dr. John Bower, an ornithologist at WWUs Fairhaven College.
Funded by Washington Sea Grant, the study repeats key elements of marine bird census work conducted in the late 1970s as part of Marine Ecosystems Analysis Puget Sound Project (MESA). The MESA study, directed by Bellinghams Terry Wahl and Steven Spiech, was the first comprehensive census of marine birds in northwestern Washington. The objective of our study is to compare our census data with the 1970s MESA census data to provide insight into changes in local marine bird abundance over the past 25 years. Results from the first year of our study have shown disturbing declines for many species in this area.
Drayton Harbor Supports Fewer Birds Than 1979
On this snowy morning, our route will take us to 12 sites, starting at the whale sculpture observation deck on Marine Drive in Blaine, looking north across Semiahmoo Bay to White Rock, British Columbia. As team members call out the numbers of birds seen, it becomes clear why the National Audubon Society has designated the Drayton Harbor area a worldwide Important Bird Area (IBA). The shoreline is filled to capacity with hundreds of dabbling ducks, including over 500 American wigeon and 300 northern pintail. Farther offshore, we count 225 white-winged scoters, 100 scaup, and smaller numbers of about a dozen other species of ducks, loons, grebes and cormorants, all actively diving for food.
After 20 minutes of counting, we pack up our scopes, jump in the car, crank the heater and make the short drive to our second site, the public dock at the mouth of Drayton Harbor. There we count hundreds more birds, including loons, grebes and five duck species in this high traffic corridor. We then methodically work our way around the perimeter of the harbor, warming our fingers with short blasts of heat between stops as we count from the town of Blaine, along Harbor Rd., to Semiahmoo spit. At our final stop, there is a crust of sparkling ice on the harbor, pushing the birds further offshore, making identification difficult.
In the car ride back to Bellingham, we add up the numbers to discover that we counted 3,606 birds over our five-hour census trip. That seems like a lot of birds, but back in the lab we find that in early January, 1979, MESA researchers censusing the same sites counted 6,406 birds, nearly twice as many birds as we saw. This type of result has been more the rule than the exception in our study. The first year of our work indicates that overall marine bird numbers along the northwestern Washington shoreline may be decreased by as much as 45 percent since the late 1970s.
Marine Birds Are Indicator Species
There are many reasons to be concerned with such changes in local marine bird abundance. One of the most important reasons is that marine birds are excellent indicator species that can help us identify changes in marine, as well as freshwater, ecosystem health. Marine birds require species-specific breeding and migratory habitat that provide food and shelter necessary for maintaining a healthy population.2
Degraded breeding habitat can lead to nest abandonment, low recruitment rates and ultimately population declines.3 Degraded migratory habitat can lead to decreased winter survival, and decreased ability to build fat reserves to continue and complete migration back to breeding grounds.4 Widespread declines in marine bird numbers very likely mean that the varied habitats used by different species are being degraded.
Unfortunately, many factors can lead to degraded marine bird habitat. Shoreline development can destroy nesting areas and impair water quality. Point source pollution such as industrial chemical releases and oil spills, and runoff from farming activity, and many non-point pollution sources such as pesticides used on lawns, gardens and golf courses, fluids leaking from vehicles, and improper disposal of hazardous material all contribute to reduced water quality and the ingestion of toxins.5
Physical disturbance by motorboats, jetskis, and kayaks, as well as people and dogs walking along beaches can decrease feeding efficiency and disturb species that nest near shorelines.6 Dredging and unstable water levels due to drought, flooding, irrigation and power projects can also affect bird populations.6 Environmental degradation that reduces the abundance of prey fish can reduce the food available to marine birds. Global climate change can also result in major changes in prey fish abundance.7
These factors act together to degrade breeding habitat and habitat used by marine birds during the non-breeding season, increasing energy demands, ultimately increasing mortality and decreasing reproductive success, resulting in population declines.2
The results from the first year of our two-year study certainly show reasons to be concerned about marine birds and the ecosystems they use. According to our preliminary data, 25 of the 35 species that were most common in the late 1970s have shown declines of more than 20 percent since that time. The seven most common species, brant goose, western grebe, surf scoter, American wigeon, greater scaup, glaucous-winged gull and Pacific loon have collectively dropped by 67 percent, including an 80 percent decline for brant, 81 percent for western grebe, and 38 percent for surf scoter.
Widespread Declines and a Few Increases
Against this backdrop of widespread declines, there are only a handful of species that appear to have increased in abundance, including double-crested cormorant (+75 percent), common loon (+71 percent), pigeon guillemot (+124 percent) and bald eagle (+189 percent).
The reasons for the decline of any particular species are complex, and are as varied as the diverse life histories of the many marine bird species that visit or breed in northwestern Washington. For some species, such as the western grebe, changes in their inland breeding areas such as loss of habitat, unstable water levels, and boat and jetski traffic on normally calm lakes, coupled with changes in forage fish populations and pollution in their wintering grounds, likely cause the declines.6 For other species, such as the surf scoter, declines are likely to be associated with the collapse of the herring spawn in local marine waters, where disruptions in spawning habitat, such as eelgrass meadows, may be affecting forage fish populations.8
Locally, negative changes in eelgrass meadows are a major threat to the nearshore foodwebs that so many marine species of various taxa are dependent upon for their survival. Eelgrass meadows in the lower intertidal and shallow subtidal zones are highly productive, converting much of the sunlight reaching them into plant material. All that primary production combined with the physical structure of the eelgrass supports the highest invertebrate biomass of the three intertidal zones.9
The large tidal exchanges found in this regions bays and harbors cause extreme shifts in habitat parameters such as fluctuations in pH, salinity and temperature as well as conditions of anoxia and desiccation that can drastically affect distribution and abundance of prey food sources.9 Concentrated and continuous eelgrass meadows provide these tidal zone organisms with protection from these fluctuations.
The rich biomass of prey species the eelgrass meadows support has, in turn, provided a smorgasbord for marine birds for thousands of years. Daily and seasonal tidal cycles determine feeding schedules. Diving birds such as grebes and scoters hunt in the eelgrass meadows for forage fish and mollusks during high tide, while brant geese graze on eelgrass leaves and forage fish spawn. During low tide, dabblers such as American wigeon and northern pintail gain access to gastropods and eelgrass leaves, seeds and rhizomes, while green-winged teals forage for amphipods.9
The return of Pacific herring, that spawn on the eelgrass, attracts a particularly high concentration of marine birds who feed on the spawn-covered eelgrass and the adult herring themselves.9 This annual event in the 1970s led to congregations of between 16,000 and 22,000 surf scoters at Point Whitehorn, Cherry Point and Lummi Bay.1 The herring spawn led to concentrations of many other species as well, such as migrant western grebes, which rely on Pacific herring as a primary food source,10 and brant geese, which graze on spawn covered eelgrass, to acquire protein to build energy reserves required to migrate to arctic breeding grounds.4
Cherry Point Herring Population Has Declined 94 Percent
There are 20 herring spawning grounds throughout northwestern Washington waters. The Cherry Point herring spawning area includes nearshore and intertidal habitat from northern Bellingham Bay to Point Roberts.10 Cherry Point is unique in that it is not only historically the largest herring spawning ground in the state, but the only spring spawning event.10
Unfortunately, according to the Washington Department of Fish and Wildlife, the Cherry Point Pacific herring population has declined 94 percent over the past two decades.10 Over the past three decades, the Cherry Point Pacific herring spawning shoreline has decreased by 80 percent, with spawning now only occurring from Cherry Point to southern Birch Bay.11 The local herring population is now classified as critical and may be in danger of extinction, due to dangerously low recruitment rates. The Northwest Ecosystem Alliance, based in Bellingham, has submitted a petition to the Department of the Interior for classification of threatened or endangered status under the Endangered Species Act.11
Although many factors may affect herring stocks, the major cause for this dramatic decline appears to be the loss of spawning habitat due to industrial pollution and development.11 According to the Whatcom County Marine Resources Committee, native eelgrass (Z. marina) has decreased 33 percent along our shoreline.12
Causes of the decline in eelgrass meadows include shoreline development where construction and poor drainage plans degrade water quality, shoreline modifications such as piers that shade eelgrass preventing photosynthesis, point source and non-point source pollution affecting water quality, and dredging where eelgrass habitat is completely removed.12 In addition, nonnative eelgrass (Z. japonica) has invaded native eelgrass meadows, possibly negatively affecting propagation of native eelgrass.13
The loss of native eelgrass and the suspicion that Pacific herring may not successfully spawn on nonnative eelgrass has likely contributed to the collapse of herring spawn populations at sites such as Cherry Point.13 One thing we know for certain, according to past studies and in agreement with our current study, is that marine birds that are dependent upon Pacific herring and Pacific herring spawn have experienced the greatest declines in our local waters.8
Potential Causes for Problems
As our census teams continue to count marine bird species along the northwestern Washington shoreline and ferry routes, it is becoming clear that our study is likely to support the conclusion that the abundance of many locally occurring species of marine birds has declined dramatically over the last 25 years. There are still many questions about why they have declined.
One clear cause of local decreases is the degradation of local marine ecosystems, but there are other potential causes for the problems we are seeing: Are there negative influences affecting their breeding grounds in British Columbia, the Alaskan and Canadian boreal forest and arctic tundra? Which species are susceptible to fishing bycatch or other human-caused changes in fish populations? Are persistent bioaccumulative toxins affecting breeding success? How do global warming and the recent increase in the frequency of El Nino events affect populations? Where do we begin to answer any one of those questions?
In the second installment of this article, we begin locally, by taking a closer look at Drayton Harbor in Blaine. We compare the changes in marine birds found there with the changes found in other parts of our study area. We ask what changes have happened in marine bird abundance in the harbor, and discuss changes in the marine environment that may have impacted the birds there.
We look to environmental changes in nearby bays and harbors and ask if those changes are displacing birds, adding pressure on Drayton Harbors ecosystem and affecting its ability to sustain migrating and resident marine birds. We also look forward, asking whether future human-induced changes to Drayton Harbor are likely to affect its ability to continue to be an Important Bird Area. §
Next Month Part Two
A closer look at Blaines Drayton Harbor.
1 Wahl, T.R. 1995. Birds of Whatcom County Status and Distribution. Bellingham, Washington.
2 Goss-Custard, J. D., Caldow R. W. G., Clarke, R. T., Durell, S. E. A., West, J. Urfi & A. D. 1995. Consequences of Habitat Loss and Change to Populations of Wintering Migratory Birds: Predicting the Local and Global Effects From Studies of Individuals. Ibis 137: S56-S66. Available: http://www.clarklabs.org/10applic/idr96cd/scheiff/Idrisicd.htm
(April 22, 2004).
4 Martin, T.E., Nygren, N.K., Dawe, and G. Jamieson. 1996. Effects of Disturbances on Spring Staging Brant (Branta bernicia nigricans) in the Parksville Qualicum Beach Area of South-east Vancouver Island, B. C. Unpublished Report, Canadian Wildlife Service, Pacific and Yukon Region. Available: http://www.ecoinfo.org/env_ind/region/brantgeese/brantgeese_e.cfm
(April 22, 2004).
5 Sibley D. 2001. The Sibley Guide to Bird Life and Behavior. The National Audubon Society Chanticleer Press, Inc., New York. 127-31 pp. 160-164 pp.
6 Storer R. W. and Nuechterlein G. L. 1992. Life Histories for the 21st Century, Western Grebe and Clarks Grebe. The Birds of North America, No. 26, The American Ornithologists Union. The Academy of Natural Sciences of Philadelphia.
7 Smith, R.C., D. Ainley, K. Baker, E. Domack, and S. Emslie, 1999. Marine ecosystem sensitivity to climate change. Bioscience. 49: 393-404.
8 Nysewander, D.R. and J.R. Evenson. 1998. Status and trends for selected diving duck species examined by the marine bird component, Puget Sound Ambient Monitoring Program (PSAMP), Washington Department of Fish and Wildlife. Puget Sound research Conference, Seattle, WA.
9 Baldwin, J.R. and Lovvern, J.R. 1994. Expansion of seagrass habitat by the exotic Zostera japonica and its use by dabbling ducks and brant in Boundary Bay, British Columbia. Marine Ecology Progress Series 103:119-27.
13 Penttila, D., personal communication cited in West, J., 1997 Protection and Restoration of Marine Life in the Inland Waters of Washington State, Puget Sound/Georgia Basin Environmental Report Series: Number 6. Available: http://www.psat.wa.gov/Publications/west_protect_restor.pdf
(May 31, 2004).
We could not have written this article without the involvement of many people, mostly Western Washington University undergraduates, in the WWU marine bird research project. Participants have been important in designing the study, collecting data through hundreds of hours of censusing, helping with analysis of the data, and for helping to interpret results. Participants who have made sustained contributions include: Marc Auten, Brian Cary, Jamie Cary, Caanan Cowles, Mary Beth DeHamer, Rainy Diehl, Kevin Dixey, Cassidy Grattan, Johanna Hobart-Crane, Alex Karpoff, Lydia Miller, Nicole Mills, Hannah Paden, Adam Peck-Richardson, Don Poe, Sandlin Preecs, Becky Rowland, Suzanne Sanborn, Marci Staub, Mark VanderVen and Geri Walker. We thank Terry Wahl for advice and for commenting on the text. Our research is funded by Washington Sea Grant # R/ES-50 and by Western Washington University Bureau for Faculty Research.
Marine Bird Abundance Changes
This table shows percent increases (+) and decreases (-) in the Southern Strait of Georgia from the MESA Study (1978-79) to the WWU study (2003-04). Species are listed in taxonomic order.
Percent Species Change
|great blue heron||+113