Stillaguamish Tribe aims to prevent heron displacement

Estuary restoration on the Stillaguamish Tribe’s zis a ba property improved habitat for salmon as well as migratory and resident birds, but unfortunately also put an active heronry at risk.

The tribe partnered with the Puget Sound Bird Observatory (PSBO) and a Monroe Corrections Complex work crew to protect the herons from being displaced.

While monitoring the avian response to estuary restoration, PSBO volunteers noticed that saltwater intrusion had compromised the structural integrity of the trees supporting heron nests.

“Many of the existing nests and roosts are disintegrating as the limbs they rely on for support are breaking from the tree,” said Cynthia Easterson, PSBO secretary and volunteer engagement coordinator.

Easterson suggested artificial heron nesting platforms as a temporary solution.

“We decided to combine the platforms with some revegetation work to see if we could provide an alternative nesting area until new saltwater-tolerant trees establish,” said Stillaguamish wildlife biologist Jennifer Sevigny.

“It will be a number of years before they are ready to hold nests,” Sevigny said. “However, the plantings will provide a benefit before they are large enough for nests because they will provide habitat complexity and vegetation density around the artificial platforms that could make them more appealing for herons.”

In March, PSBO volunteers, tribal staff and a work crew from the Monroe Corrections Complex installed five 25-foot poles, buried 6 feet deep for stability, with 10 nest platforms beside the heron rookery. In addition, the Monroe crew provided weed control and planted 2,500 native trees, shrubs and ground cover.

“Logistics for this project were complicated due to high tides and a narrow tidal range throughout the month prior to nesting,” said Stillaguamish wildlife biologist Amanda Summers.  “The poles were towed to the site by boat and hand set.”

The Stillaguamish Tribe restored approximately 100 acres of tidal wetland in 2017, naming it zis a ba for a tribal chief. The area contains habitat for a variety of waterfowl, shorebirds and songbirds, as well as the heronry of up to 26 active nests. Large numbers of herons nest there seasonally while a smaller group roosts there year round.

“PSBO will provide monitoring of the heron colony to assess the use of artificial nest platforms with an eye toward other declining heronry sites, particularly in restoration areas, that may benefit from a similar approach,” Easterson said.

Volunteers, tribal staff and a corrections work crew install artificial heron nest platforms in the zis a ba estuary adjacent to the trees that support about 26 heron nests. Photo: Elaine Chuang, Puget Sound Bird Observatory Board of Directors

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