Monday, April 14, 2008


Tiny bird outwits Campbell plan for Roberts Bank expansion

Discovery about birds' food raises concerns about plan for Roberts Bank terminal

Margaret Munro,
Canwest News Service
Published: Monday, April 14, 2008

An international team has discovered why half the world's western sandpipers touch down on a specific tidal flat just south of Vancouver every spring. The secret is in the mud, more specifically in the snot-like "biofilm" coating the mud.

The tiny shorebirds, weighing about 30 grams each, suck a remarkable 20 tonnes of the sticky slime off the mud every day as huge flocks swoop down to refuel during the spring migration, the scientists estimate.

The discovery is big news for birders, who have long assumed sandpipers eat bugs and worms. "Snot feeding," as Environment Canada biologist Bob Elner describes it, adds a whole new dimension to avian life.

It also has big implications for a proposed $1-billion federal port expansion at Roberts Bank in the midst of what is widely considered Canada's most important bird habitat. The plan is to double the size of the existing port directly in front of the mud flat where one to two million sandpipers -- half the world's population -- stop in April and May as they migrate from the tropics to breeding grounds in the Arctic.

It is an open question whether the sandpipers, whose numbers appear to be declining, and the ever-expanding port can co-exist. Understanding the impact of the controversial port expansion on the biofilm will be a "critical part" of the federal environmental assessment, says Elner, a biologist with the Canadian Wildlife Service.

He and his colleagues from Japan, France and Burnaby's Simon Fraser University spent close to six years figuring out why the sandpipers are so partial to the Roberts Bank mud flat. "Everyone thought 'It's just mud, we've got tonnes of the stuff,' " says Elner. "But it's not just mud. It's quite precious mud," he says, pointing to the thick brownish-grey goo that stretches for 6,000 hectares at low tide.

What sets the mud apart is the biofilm laid down as bacteria and diatoms settle out of the sea water, the researchers say. The micro-organisms secrete mucus that binds them to the mud, so they won't wash up with the tide. "It's a mucopolysaccharide, which is the same as snot basically," says Elner.

He says biofilm is common to all aquatic ecosystems but Roberts Bank produces an extraordinary amount because of the tidal currents and nutrients flushing out of the Fraser River.

"It's been known to exist for eons, and regarded as something a few snails fed on, but it's never been thought of as a bird food," says Elner, whose team has shown the energy-rich slime is the main source of nutrition for the giant flocks of sandpipers that descend on Roberts Bank. They suck up the biofilm with their hairy tongues and specialized beaks. {Snip} ...

The researchers' discovery adds a new twist to conservation with the biologists calling for not just protection of the birds, but the biofilm they eat. Threats to biofilm, Elner and his colleagues say in their report, should be assessed when considering future coastal development.

More about sandpipers at Roberts Bank:


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