Point Defiance Zoo & Aquarium has installed new nest boxes to help attract Purple Martins back to Tacoma, hoping to revive a local colony crucial for pest control.
TACOMA, Wash. — Experts are closely monitoring a new set of nest boxes recently installed along Ruston Way that they hope will attract and rebuild a local colony of Purple Martin, North America’s largest swallow.
Staff from Point Defiance Zoo & Aquarium relocated 16 nest boxes to a berm south of Chinese Reconciliation Park this month after the birds’ previous homes were lost.
In fall 2024, boxes and gourds attached to deteriorating wooden pilings in front of Dickman Mill Park were removed when the state dismantled the pilings.
“We’re hoping the offer of waterfront homes will lure some of the experienced birds back to Ruston Way and they’ll set up shop there,” said Zach Hawn, conservation coordinator at Point Defiance Zoo & Aquarium.
Purple martins migrate to Washington from Brazil each spring, typically arriving in early April and departing by late August. The dark purple-and-blue birds historically nested along Tacoma’s shoreline, but their numbers have dwindled significantly in recent decades.
The Washington Department of Fish and Wildlife lists purple martins as a Species of Greatest Conservation Need, a designation indicating human intervention is necessary for the birds to thrive. Conservative estimates place the statewide population at roughly 600 adult birds, with Tacoma potentially home to as much as 16% of that total. By comparison, purple martin populations on the East Coast number in the millions.
Hawn said the decline on the West Coast dates to the 1930s, when large-scale logging removed the old-growth timber that contained the natural cavities the birds used for nesting. The arrival of nonnative species such as house sparrows and starlings around the same time increased competition for the remaining habitat.
“Due to historic forestry practices, as well as waterfront development, their breeding habitat was pretty reduced, which led to a steep decline in their population here in our state,” Hawn said.
The loss of natural nesting sites made the birds almost entirely dependent on human-made housing. Point Defiance Zoo & Aquarium has supported the local population since 2013 through a community monitoring program that trains volunteers to track breeding behavior.
It is unclear exactly how many birds were displaced when the Dickman Mill pilings were removed, but community monitors counted 34 adult birds at that location. Zoo staff added 16 nest boxes at the Point Defiance Boathouse last year to help absorb displaced birds, and population counts at nearby colonies rose in 2024.
“We saw a rise in population at other purple martin colonies in the area last year, so we know the birds are nearby,” said Sam Hain, conservation specialist at Point Defiance Zoo & Aquarium. “This is an important species right here in our backyard that needs help, and we will continue to support them any way we can.”
The birds were spotted locally in early April, and Hawn said the new colony site near Chinese Reconciliation Park could attract them because of its proximity to established colonies at the Port of Tacoma. Purple martins are colonial nesters, meaning the grouped boxes are designed to mimic the social environment they prefer.
Beyond their conservation value, the birds are known for eating insects while in flight, making them a natural form of pest control around waterways. They are also recognized for a distinctive vocalization known as the Dawn Song.
“They kind of sound like sci-fi laser guns or R2-D2,” Hawn said. “Quite an interesting species.”
The Washington Department of Fish and Wildlife is planning a statewide population survey this year. People who spot purple martins can report observations through the agency’s wildlife reporting form at Washington Department of Fish and Wildlife. Volunteers interested in joining the monitoring program can visit Point Defiance Zoo & Aquarium.
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