Down between the train tracks along Ruston Way and the shoreline of Commencement Bay in Tacoma stand small, cedar-clad boxes. These tiny dwellings, hoisted about 16 feet above the ground, aren’t suitable for humans. These are new nesting boxes for birds, specifically purple martins.
“We're hoping though, now with the Ruston Way colony, that this will again be a nice home for those birds to come back this summer,” said Zachary Hawn, the conservation program coordinator for Point Defiance Zoo and Aquarium.
Each spring, purple martins migrate from Brazil to the western United States, to breed and nest here over the summer.
The birds are one of the larger swallow varieties. The males have iridescent purple-blue feathers with black wing tips, and the females are gray and blue. Some describe the birds’ very distinct call as reminiscent of R2-D2, the robot sidekick from “Star Wars.”
The birds are cavity-nesters, which means they nest in small openings — like in dying trees or rock crevices. But shoreline development, as well as forestry practices like removing snags where the birds would otherwise nest, mean their natural habitat options have become limited.
That’s where manmade nesting boxes, like the ones on the Tacoma waterfront, come in.
Purple martins in Washington
“These structures here are what is giving them the ability to maintain breeding territories here in the state and on the shores of the Salish Sea,” Hawn said. He was part of the team that set these nesting boxes up earlier this year.
In Tacoma, there are at least two other nesting sites like these for the birds along the shoreline of Commencement Bay.
“The increase in provided cavities, human-made cavities, has been beneficial in being able to supplement what's been lost,” said Christa LeGrande, who works for the Washington State Department of Fish and Wildlife. She monitors birds, including purple martins.
But the state doesn’t know how beneficial the nesting boxes are because they don’t have a recent count of the birds.
That’s why the Washington Department of Fish and Wildlife is planning to do an updated survey of purple martins. The last state assessment, done over 20 years ago, estimated there were between 600 and 700 breeding pairs here. The birds are listed as a species of greatest conservation need.
LeGrande said it's important for the state to have that to answer questions about where the birds are finding habitat and how the state can help them survive, and possibly even thrive.
The department wants to answer questions on whether the numbers are increasing or decreasing, and what structures the birds prefer to nest in. Surveyors will visit locations where purple martins have nesting boxes or have otherwise been observed.
“We may have upwards of 16% of the state's population of birds here nesting on the shorelines of Tacoma,” Hawn said. “ It's good habitat, so we have a lot of water, a lot of open spaces, and also some long-standing colonies. And so it's places the birds know is the right space for them.”
Human involvement
To ensure this good habitat, humans have to be actively involved. These nesting boxes on Ruston Way were installed here after being removed from a different site over a year ago, because the boxes were mounted to derelict, creosote-soaked pilings.
That’s the tricky thing about birds relying on humans for their housing — humans’ habitats change. The nesting boxes have to be managed heavily to prevent other birds, harmful predators or insects from getting in.
“People get old, they lose interest, they die,” Kelly McAllister said. “So things start to fall apart a little bit.”
McAllister is volunteering to help with the state survey. He’s retired now, but McAllister used to work for the Washington Department of Game, tracking breeding and nesting sites for purple martins.
McAllister thinks there is hope in these manmade structures. He said they might be helping the birds establish more in an area and eventually find natural cavities to nest in instead.
“ It's become clear that where you have these nest box programs, you can attract martins,” McAllister said. “And then once you've done that, they start to appear in natural cavities nearby.”
Like the Black River, by Glacial Heritage Preserve, where there’s been a clear cut. McAllister said he’s seen purple martins nesting in the snags and he thinks that’s because of the nearby manmade nesting boxes.
Once the census is done, McAllister said he thinks the results will show that there's been an increase in these birds because there's greater habitat diversity in Washington.
“I expect that this census effort is going to show that there's more pairs than we ever knew about before,” McAllister said.
