Study: Swallows serve as canaries

Researcher looks for pollutants in birds' nests

Posted: Wednesday, June 07, 2006

At first glance, the motionless bird appeared dead as biologist Deb Rudis used a mirror to peek into the nest of grass and feathers.

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Rudis reached her hand into the nest box - one of 50 recently staked in marshes around Juneau - and lightly touched the tree swallow.

The small bird moved, and Rudis smiled.

It was yet another healthy bird, intent on incubating her clutch of marble-sized eggs.

Rudis will monitor the tree swallows and their fledglings born in the new nest boxes for the next three years.

A U.S. Fish and Wildlife Service contaminants biologist, Rudis hopes to learn more about the tree swallows' nesting survival in Juneau and whether the birds are affected by any pollutants. Rudis will compare the nesting success rates of tree swallows in five locations around Juneau - from ponds near the landfill in Lemon Creek to the banks of the Mendenhall River. So far tree swallows have colonized at least 13 of the boxes - a surprisingly high success rate of about 26 percent, Rudis said, adding she didn't expect a success rate above 10 percent.

The study, launched in May, is the first tree swallow study in Southeast Alaska. Similar studies have been done in other parts of the country, including Rhode Island, Colorado and the Midwest.

Tree swallows are the guinea pig of bird contamination studies across the United States. They are popular among scientists due to their simple diet: They eat aquatic insects right on their home turf.

If nearby stream sediments are polluted, the insects pick up the pollutants and pass it to their predators, the swallows. The swallows can relay contamination to their eggs or feed their fledglings contaminated bugs.

Rudis hopes to find little contamination in Juneau's swallows. But elsewhere in the United States, tree swallows continue to suffer biological harm from lead contamination caused by late 1800s' mining activity and severe hatching problems due to dioxin pollution. Dioxins are commonly produced during the burning of fossil fuels.

For now, Rudis is watching the nest boxes, intent to learn whether their eggs will hatch. She visits each box three to five times a week.

Any eggs that fail to hatch will be studied in a lab for the presence for organic chemicals - ranging from pesticides to banned, fire resistant compounds called polychlorinated biphenyls, or PCBs.

When the chicks can be handled, they also will be banded for long-time monitoring, Rudis said.

Rudis gained permission to install nest boxes in the marshes and ponds in the Lemon Creek area, home to Juneau's landfill and former incinerator, and other locations including the state game refuge.

Many of the nest boxes are visible to anyone driving down Juneau's major highway, Egan Drive.

"I get a lot of ... 'Oh, that's what the boxes are for,' " Rudis said Tuesday.

The spruce and cedar nest boxes were built by Juneau carpenter Ken Kitka, who received some volunteer assistance from residents of the Glacier Manor Half-way House.

Juneau's Boy Scout Troop 11 installed the boxes on wooden stakes as part of a community service project.

Boy Scout Nick Waldo said he clocked five and a half hours on the project, digging 2-foot-deep holes for the nest boxes in the rainy part of May.

"It was pretty much walking in the marshes, when it was raining, and digging holes, but it was fun," Waldo said.

"It sounds like a really interesting study that they are putting together," Waldo added. "I never knew much about tree swallows at all," he said.

Though their name implies otherwise, tree swallows prefer to make their nests in open, marshy areas. They usually make their homes in hollow, old snags.

For those who want to go looking, tree swallows don't just nest in the Mendenhall Wetlands area. They can also be found in the meadows near Kowee Creek, said Bob Armstrong, a Juneau biologist and bird enthusiast.

• Elizabeth Bluemink can be reached at elizabeth.bluemink@juneauempire.com.



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