Conservation Projects: How are we learning about Western Bluebirds?

Ecostudies Institute is working to reestablish breeding populations of western bluebirds in the Pacific Northwest using reintroduction, population monitoring, and outreach. In collaboration with numerous US and Canadian partners, our goal is to ensure this iconic species can inspire future generations and serve as an emblem for oak-prairie conservation.

Western bluebirds (Sialia mexicana) are a charismatic, brilliantly blue songbird that can be found in a variety of habitats throughout the western U.S.. On the west side of the Cascades, they are one of the many species that historically relied on mature Garry oak woodlands. Today, they are impacted by habitat fragmentation and the loss of old oak trees with natural cavities.

Western bluebirds are listed as a Species of Greatest Conservation Need in Washington due to their declining population. Ecostudies Institute works closely with many partners in the US and Canada to restore key oak woodland habitat and rebuild western bluebird populations throughout the northwest.

What is a Western Bluebird? Learn more about these oak woodland birds here.

Western bluebird family group in an aviary aboard the "bluebird uber," being transported to Canada for the Vancouver Island translocation project. (Connor Tracey 2024)

Since 2007, Ecostudies has collaborated with many partner organizations on recovery plans for western bluebirds on San Juan Island and Vancouver Island. Adults and family groups with young nestlings are transported from Joint Base Lewis-McChord to their new homes on the islands, where partner biologists observe them closely in large aviaries before releasing them. Monitoring translocated pairs and family groups provides necessary information about stress responses, nest success, and site fidelity that inform ongoing translocation projects and habitat restoration.

Key Findings on the islands: What have we learned so far?

Western bluebirds have demonstrated tolerance to the stress that comes with translocation - being trapped and transported over 100 miles by car - and have adapted to new territories on San Juan Island and Vancouver Island, BC, and several have become year-round residents. Translocation efforts have resulted in the establishment of small breeding populations on San Juan Island and Vancouver Island, and continued translocations are expected to bolster the populations.

Most of the birds on the islands fledged there, indicating that surviving young are successfully returning to their birthplaces.

A female that fledged on San Juan Island dispersed to Vancouver Island, and a female that fledged in South Puget Sound dispersed to San Juan Island. These movements show the connection among populations and highlight the need to focus conservations efforts at the regional scale.

Volunteers working with the Washington Department of Fish & Wildlife branch on Joint Base Lewis-McChord have been critical for building and monitoring a robust nest box network on base. During the breeding season, the boxes are checked regularly by Ecostudies avian technicians to monitor general breeding successes, occupancy, and to determine the family groups that will be transported to either the San Juan islands or Vancouver island. Adults and nestlings are banded in the summer for future identification - returning banded birds can indicate site fidelity and survival in wintering areas.

Key Findings at JBLM: What have we learned so far?

Long-term monitoring on JBLM has shown that western bluebirds respond well to artificial nesting sites in areas where natural cavities are rare. Currently, an estimated 200 pairs of bluebirds breed on base, almost all of which use man-made nest boxes.

Western bluebird nestlings in hand, demonstrating sexual dimorphism. (2022)

Female western bluebird with her brood (JBLM volunteer 2024)

Critical Habitat: What threats are Western Bluebirds facing throughout their range?

While not rare range-wide, western bluebirds are uncommon in western Washington due to the loss of mature Garry oak woodlands, and displacement by European starlings, house sparrows, and other invasive cavity-nesting birds. They were extirpated from the San Juan Islands by the 1960s and Vancouver Island in British Columbia by the 1990s, where Garry oaks were cleared to make way for development and livestock pasture.

Widespread use of pesticides in agriculture has caused a decline in the insect prey that bluebirds rely on. Nestling bluebirds require vast quantities of insects from grasshoppers to caterpillars to develop properly and reduced numbers of high-nutrient insect prey impact survival, especially in years with unseasonable weather events.

The most stable breeding population of western bluebirds in Washington is found on Joint Base Lewis-McChord (JBLM), where a volunteer-run nest box program initiated in 1983 and extensiveoak-prairie restoration have allowed them to thrive. This population serves as a "donor" for translocation efforts on San Juan Island and Vancouver Island, BC.

Want to see more of what we are doing for birds? Follow Ecostudies social media for weekly field photo highlights, project updates, and event announcements!

Looking Forward: What does future conservation of Western Bluebirds look like?

Future reintroductions at San Juan Island and Vancouver Island are necessary to maintain a breeding population of western bluebirds, and continued efforts to restore habitat and mitigate predator- and human-caused disturbances will allow increased resiliency against mortality from all causes. Other efforts such as the construction of more nest boxes, further coordination with partners on the islands through public outreach, and translocating western bluebirds to other areas on the islands to combat the effects of a small population will help increase overall success of populations on San Juan and Vancouver islands.

Restoration of Garry oak woodlands on Joint Base Lewis-McChord continues to expand viable habitat for bluebirds and other oak-prairie species. Prescribed fire frees oak woodlands of competing vegetation, and increases soil nutrients.

Efforts to understand factors contributing to nesting success are ongoing, with new projects expected to expand our understanding of these iconic birds beginning in the spring of 2025.

A western bluebird at a nest box (2014)

Public Involvement: How can I help?

While most of the on-the-ground research of western bluebirds is conducted by biologists at Ecostudies and partner organizations, there are opportunities for the public to contribute toward western bluebird recovery.

  • Citizen Science - Ecostudies uses eBird historical records and observation data allow us to make inferences between past and present management strategies. By submitting observations of western bluebirds to eBird, the public can help biologists understand the bigger picture. To report banded bluebird sightings, Contact Us.
  • Conservation at Home - Support for wild birds can be as simple as learning about your local wildlife, planting native species in your garden, and keeping your cats indoors.
  • Policy - Public policy plays an important role in the conservation of at-risk species, including western bluebirds. You can be a voice for your feathered neighbors by supporting federal and state legislation that limits the use of dangerous pesticides, designates land for protection, and allocates funding for conservation work, like what we do here at Ecostudies.
  • Join the Crew - Ecostudies offers employment opportunities for seasonal work in western bluebird conservation. Learn more about our currently available positions!
  • Donate - Support Ecostudies Institute with donations!