OLYMPIA - With the recent acquisition of 30 acres of critical great blue heron nesting habitat on Camano Island, conservationists can now focus on learning more about the potential decline of the bird.
Protection of the Davis Slough "heronry" was finalized in October when the Whidbey Camano Land Trust and the Friends of Camano Island Park raised an estimated $250,000 in donations from more than 500 individuals. These funds were in turn matched by an Island County Conservation Futures grant of $255,000 and provided enough money to purchase the property.
The heronry is one of the five-largest concentrations of great blue herons in the state, with an estimated 400 birds and nearly 200 nests scattered throughout the 30-acre parcel.
The property's previous owner had listed the land for sale and was entertaining offers from developers interested in converting the acreage into homesites.
Acquisition of the heronry site comes at a time when biologists with the Washington Department of Fish and Wildlife (WDFW) and the Canadian Wildlife Service are stepping up efforts to monitor the Puget Sound subspecies of great blue herons and develop a plan for protecting the birds.
"There is some evidence that indicates the Puget Sound sub-population of the great blue heron is declining, and we want to gather as much information on possible on food sources, habitat uses and other life history facts," said Ruth Milner, a WDFW wildlife biologist.
The subspecies ranges from southern Puget Sound north into lower British Columbia, and has been designated as a "species of concern" by the federal government in Canada. Herons have protection under the Migratory Bird Treaty Act in both nations.
Great blue herons are a familiar sight along the Puget Sound shoreline and on freshwater wetlands. They are the largest heron in North America, standing more than four feet tall with a six-foot-wide wingspan. The birds feed primarily on small fish and amphibians, but also eat snakes and insects.
Milner said the Davis Slough property is perfectly located for herons.
"This site is on the north end of Camano Island, so it's an easy flight for the herons to get to Port Susan Bay and south Skagit Bay, which are both very large tidal areas that offer a rich and diverse variety of food for the birds," she said.
"The trees that the birds nest in are also relatively well-buffered," Milner said. "Even though it's in an area that's becoming increasingly surrounded by development, the birds can still find refuge at Davis Slough."
Gerry Hayes, a WDFW biologist and a member of a new U.S.-Canadian heron work group, said getting an accurate heron population estimate for the region is proving to be a challenge for several reasons.
"We don't want to disturb nesting sites during critical mating and rearing times, and nests can be obscured by leaves after leaf-out occurs," he said. "The birds also tend to move around quite a bit."
The heron work group is developing a plan to assess great blue heron numbers based on counts made in the estuaries where the birds feed.
"The birds are out on the tidal flats regularly. We want to see if there are relationships between the birds seen in the colonies and birds seen foraging on the nearby flats," he said.
The group has proposed to count the number of birds within several small, medium and large heronries throughout Puget Sound, identify nearby tidal areas, and count the number of birds in those areas.
Biologists will begin their survey work in the early spring, and plan to keep counting birds well into summer.
The health of the great blue heron population in Puget Sound is a reflection of the health of the sound itself, Hayes said.
"Herons are a good indication of trends in different fish species within the marine food chain, contaminants, and of what's happening in the uplands, including disturbance, land-use changes and other factors," he said.