Drayton Harbor as Critical Marine Bird Habitat: Is the Harbor Ecologically Stable?

Holly Donovan is a 2004 graduate of Huxley College of the Environment at Western Washington University, where she interned with Dr. John Bower. She’s 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 Washington 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.

Part Two

Editor’s Note: Part one appeared in the December 2004 issue, page 4.

Conducting a marine bird census requires sharp identification skills, a good set of raingear and patience in the lab where the data crunching occurs. Together with the help of over 20 Western Washington University students, we have analyzed our first year census data to compare the numbers of birds we are finding in northwestern Washington’s bays, harbors, passes and straits to those found by researchers counting birds in the same places during the 1978-1979 MESA study.

The story that is unfolding is troubling (see part one in the previous issue). Our data indicates an overall decline of 45 percent in marine birds, including declines of more than 20 percent in 25 of our most common 35 species. Some species are showing alarming decreases of 50 percent or more.

Furthermore, the declines we are seeing largely parallel the declines seen by Puget Sound Ambient Monitoring Program (PSAMP) researchers, in the only other major study of recent local marine bird abundance changes. In this part of our two-part series, we focus on the changes we are seeing in one local body of water—Drayton Harbor. The National Audubon Society has designated the Drayton Harbor area as a worldwide “Important Bird Area” (IBA), and the recent growth in the human population around the harbor makes it a good example of the types of pressures marine ecosystems are experiencing in the Pacific Northwest. It also provides insight into ways we can positively affect the marine environment through habitat enhancement and restoration.

The story told by our first year of work in Drayton Harbor is similar to what we have seen for our entire study area along the northwestern shoreline from Tsawwassen, British Columbia and Point Roberts to Whidbey Island. In Drayton Harbor we have also seen large declines, but only 14 of the 35 most common species have declined by more than 20 percent. According to our first year data, the total number of birds in Drayton Harbor has declined by only about 10 percent since the 1970s. The MESA researchers found, on average, 6,058 birds in Drayton Harbor, whereas in our first year we counted an average of 5,477 birds.

At first glance, this appears to indicate that Drayton Harbor’s marine ecosystem is a productive ecological food web, supplying each trophic level its energy requirements. However, upon closer inspection, we see a more complex picture. For instance, the western grebe, red-necked grebe and American wigeon have declined 57 percent, 75 percent and 72 percent respectively in Drayton Harbor, rates which are similar to their decline in the rest of our study area.

On the other hand, some species for which we are seeing study-wide declines have increased, remained stable or suffered smaller decreases in Drayton Harbor, including surf scoter (–45 percent study-wide versus +57 percent in Drayton Harbor), brant goose (–84 percent vs. –4 percent), and greater scaup (–74 percent vs. –16 percent). Finally, some of the species that have increased in the harbor are species for which there is little local population concern such as glaucous-winged gull (+91 percent in the harbor), bufflehead (+48 percent) and double-crested cormorant (+243 percent).

Since marine birds are excellent environmental indicators (see part one) it makes sense to ask: what are the birds telling us about habitat health in Drayton Harbor? How has the Drayton Harbor ecosystem changed over the last 25 years? Can Drayton Harbor continue to support the many species of waterbirds depending on its ecosystem?

Marine birds depend upon site-specific habitat for non-breeding and breeding requirements, which can make them important indicator species that can help researchers to understand shifts in habitat function. The fact that a number of species are faring better in Drayton Harbor than in other parts of our study area indicates that Drayton Harbor may be more ecologically stable than many other local bodies of water.

The Drayton Harbor area, including the adjacent Semiahmoo Bay, is an essential stopover in the Pacific flyway and a vitally important link in the marine ecosystem of the southern Strait of Georgia. This area provides forage habitat for many migratory marine birds, such as the surf scoter, western grebe, greater scaup, bufflehead, northern pintail, American wigeon and brant goose.

These birds are especially dependent upon Drayton Harbor’s eelgrass meadow habitat. Eelgrass meadows support species from many taxonomic groups; including forage fish that are essential prey for many marine bird species (see part one). Some of the marine bird species showing the greatest declines in abundance are species that are most dependent upon forage fish as their primary food source.1

Washington Department of Natural Resources (WADNR) surveys estimated approximately 200 km to 450 km2 of eelgrass coverage throughout Puget Sound and the Strait of Juan de Fuca with Padilla Bay supporting 20 percent of total eelgrass concentration. Eelgrass abundance in Washington state has declined 33 percent.3 Previously continuous eelgrass meadows have been fragmented and some critical forage fish spawning areas have experienced alarming eelgrass declines, such as Westcott Bay in San Juan County.2 In Whatcom County, WADNR shorezone inventory data shows 55 percent of 147 miles of shoreline containing eelgrass.4

In Drayton Harbor, rapid shoreline inventory volunteers coordinated and trained by the Whatcom County Marine Resources Committee, RE Sources and People for Puget Sound surveyed habitat types along 11,700 feet of shoreline. Surveyors found that 55 percent of the Drayton Harbor shoreline contained continuous eelgrass habitat, while 40 percent showed patchy eelgrass, and only 1 percent of shoreline contained no eelgrass.3

While historical data for eelgrass coverage in the harbor is lacking, the high percentage of shoreline currently showing eelgrass supports the assertion that Drayton Harbor’s eelgrass habitat has largely been maintained. Future nearshore habitat surveys will assist scientists to continue to monitor this critical component of Drayton Harbor’s ecosystem health and can also help guide future restoration and habitat enhancement efforts.

Marine birds appear to have benefited from one eelgrass enhancement project that has added 15 acres of eelgrass meadow to the harbor. During the summer of 1998, Pacific International Engineering Environmental Services (PI Engineering) dredged 300,000 cubic yards of mudflat as part of the expansion of the Blaine Marina. The dredged sediments were deposited about one mile offshore from Dakota and California Creeks, essentially creating a new 15-acre subtidal mudflat.5

During the winter of 1998 and 1999, native eelgrass (Zostera marina) was planted in this new mudflat. According to Art Choate from the Port of Bellingham, recent monitoring has shown that the transplanted eelgrass is growing and there is evidence that native eelgrass has also colonized from adjacent eelgrass meadows. Choate also indicated that recent monitoring has not detected encroachment of nonnative eelgrass or alga species. According to PI Engineering, this new eelgrass meadow is supporting benthic and epibenthic invertebrate populations.5 The apparent sustainability of established eelgrass meadows and this newly created habitat are likely responsible for the relatively high numbers of marine bird migrants identified during our Drayton Harbor census work.

We have focused on how marine habitat can affect marine bird populations, but birds can also degrade habitat. For instance, double-crested cormorants can displace other species by competing for nests and breeding habitat. They can also cause significant damage to vegetation within their nesting and roosting sites as guano deposition can kill vegetation, and bark stripping for nest building can kill trees. This can affect the survival of other species, including rare plant species.6

In Drayton Harbor, birds have been suspected of contributing to the harbor’s long-standing water quality problems. For years, Drayton Harbor water samples have contained high levels of fecal coliform. Fecal coliform itself is not a primary health concern; however, high colony counts of fecal coliform may indicate the presence of pathogenic microorganisms in the water that may pose a health risk to humans and other members of the biological community.7

Suspected sources of fecal coliform found in Drayton Harbor have included agriculture and urban runoff, failing septic systems, boat ballast, fish processing waste, and force main and sewage leakage. Despite admirable efforts taken to understand, find and eradicate sources of fecal coliform, high fecal coliform counts in parts of the harbor have continued, especially within the commercial core of Marine Drive.8

Raised eyebrows have recently been looking toward the breakwater covered with nesting gulls and cormorants. Double-crested cormorants are attracted to the southwest corner of the breakwater for nesting and to the many roosting and resting sites the harbor offers. Our data has shown that double-crested cormorants have increased 243 percent in Drayton Harbor since the 1970s, and thus could be contributing to increased fecal coliform in this area.

Glaucous-winged gulls have shown a decrease throughout our study area, but have increased 91 percent in Drayton Harbor. Both the gulls and the cormorants tend to congregate along the breakwater near where the highest fecal coliform counts have been measured. Another possible fecal coliform source is the many harbor seals that sun themselves and feed near the mouth of the harbor. It is possible that these species may be contributing to Drayton Harbor’s fecal coliform dilemma.

However, Geoff Menzies, Chairman of the Drayton Harbor Shellfish Protection District Advisory Committee, reports that dye studies have shown that, while high fecal coliform concentrations may occur very close to the breakwater, they are not likely to result in high counts in other parts of the harbor. At this point, there is no direct evidence linking either the birds or the seals to the problem.

Our data suggests that while many species of marine birds have shown decreases in abundance in Drayton Harbor over the last 25 years, the losses have been less extreme than in other parts of our study area. There are many reasons contributing to these changes. We still do not know how much of an impact factors such as fishing bycatch, climate change and persistent toxins in breeding and wintering grounds are affecting local marine bird abundance.

However, one factor contributing to these declines does seem clear: changes in our watersheds, due to the increase in the human population, are degrading local marine habitats. In Washington state, 30 percent of 3,067 miles of shoreline have been modified4 with inevitable consequences for marine ecosystems.

In Whatcom County, where 34 percent of 147 miles of shoreline has already been modified,4 shoreline development is a constant environmental concern. Current plans by Trillium Corporation to build a 72-unit condominium development on Semiahmoo Spit provide an excellent example of the types of issues faced locally. If this proposed development occurs, it will almost surely negatively impact the marine environment and will likely result in continued irreversible decreases in marine birds in this important bird area, in much the same way that other shoreline development has in the past.

Semiahmoo Spit is a unique habitat in Whatcom County, featuring an unusual terrestrial biological community and providing excellent habitat for waterbirds and shorebirds. Our data shows a 45 percent decrease in overall marine bird abundance west of the spit over the last 25 years, an area that includes the original development of the Semiahmoo Resort.

Past studies in other areas have demonstrated that alterations to the migratory habitats used by birds can result in increased energy demands, ultimately increasing mortality and decreasing reproduction efforts.9 The activity of approximately 150 new residents on the spit cannot help but negatively impact the birds near Semiahmoo Spit. Simply walking on the beach disrupts foraging and forces waterbirds and shorebirds to repeatedly relocate, resulting in lost energy and increased stress. Walking dogs on the beach compounds the problem. Birds regularly disturbed in this way may have a difficult time maintaining fat reserves required for winter survival and spring migration.10

In addition, pollution and discharged fluids resulting from hundreds of vehicle trips by new residents, as well as runoff from the new impervious surfaces, will contribute to degrade water quality in Drayton Harbor, ultimately affecting marine habitats and the birds that rely upon them.

Brant geese illustrate the importance of Semiahmoo Spit as important marine bird habitat. Brant utilize our region as a staging area during the fall and spring migration. Brant are dependent upon gravel and grit as an important aid in the digestion of plant fiber. The gravel bar at the northern tip of Semiahmoo Spit was dredged and replaced by a marina in 1980, removing the site where brant traditionally gathered grit.11

Continued development on the spit may further reduce the ability of brant to forage successfully in Drayton Harbor. Although brant abundance has remained stable in Drayton Harbor, the species has decreased a staggering 84 percent across our study area. Since Drayton Harbor provides important foraging habitat for brant, we should be particularly careful not to disturb this sensitive habitat that brant rely upon.

Further development of Semiahmoo Spit will almost certainly degrade nearshore marine habitats and negatively impact waterbird and shorebird abundance along the spit for brant and other species. Given this, citizens and city planners would be wise to oppose shoreline development in such sensitive shoreline habitat.

As our human population bulges, anthropogenic stressors on our watersheds increase, resulting in altered and lost habitat. As habitats degrade and diminish, seemingly productive habitats become less efficient as more pressure to provide energy is required. Eventually, as the carrying capacity of a habitat becomes overloaded, increased pressure may overcome and leave a habitat dysfunctional, forcing birds elsewhere to find forage and shelter.12

The changes in marine bird abundance documented in our study are a call to researchers and conservationists to focus on changes occurring along our shoreline. By understanding the causes of changes in marine bird abundance in breeding and non-breeding habitats, we can look into the future and take actions to preserve critical habitat needed to sustain species that inhabit them. Such an effort would help stabilize bird populations, and would also benefit other species that use the same habitats.

As marine bird species become more displaced, care and effort must be taken to ensure places of refuge where food, shelter and protection are provided. Conservation efforts targeting water quality, shoreline protection and eelgrass habitat restoration will help provide the required seasonal prey availability to sustain historic marine bird populations.

In class discussions for the students involved in the census, the critical question comes up over and over, do the residents of northwestern Washington have the will to minimize their impact on marine ecosystem health, or even perhaps make steps towards restoring marine ecosystems to their previously functional state? Can members of the community take the initiative to become good stewards of their own shorelines and make a difference? The answer is not yet clear, but one thing seems obvious: the birds are in trouble, and are depending on us to choose the right answer. §

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, spending hundreds of hours collecting data, 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 throughout our study. Our research is funded by Washington Sea Grant #R/ES-50 and by Western Washington University Bureau for Faculty Research.