Common Loon

Nesting common loon

Nesting common loon, photograph taken by the National Wildlife Federation.

Common loons (Gavia immer) are a frequent migrant and wintering species within Washington State. They winter primarily on coastal and inland marine waters, and number in the several thousands. Most common loons breed in Canada and Alaska, but some breed in northern states, including Washington.

Common loons require large wooded lakes with dense populations of fish to provide undisturbed shoreline areas for nesting and sufficient food for both adult and young. Loons nest at the edge of the lake because the position of their legs is superbly adapted for swimming, but makes walking difficult.

In the Cedar River Municipal Watershed, Chester Morse Lake and the adjoining Masonry Pool provide relatively undisturbed habitat for nesting loons. Because rising water can flood and falling water levels can strand stationary nests at the lake edge, city biologists construct small floating nest platforms. The platforms rise and fall as water levels fluctuate within the reservoir, giving the loons a more stable nest environment and a higher chance of reproductive success.

Read more about common loons on the Seattle Public Utilities Cedar River Biodiversity website.


Our goal is to continue to support common loon nesting in the watershed. Specifically we will:

  1. Protect water quality for common loons and their prey
  2. Avoid or minimize disturbance in seasonal nesting and rearing areas
  3. Enhance stream and riparian habitat to benefit fish, a major food source for common loons
  4. Provide alternatives for common loon nesting habitat by continuing to deploy artificial nesting platforms when environmental conditions are favorable


What are we doing for common loon?

Protect All Watershed Habitats
Management of the watershed serves to avoid or minimize adverse effects from major natural or human-caused events such as fire, spills of toxic materials, invasive species, and excessive human disturbance. Protecting Chester Morse Lake and its tributary streams from toxic spills, removing invasive species in its associated riparian areas, and protecting the forests in the upper watershed from fire will maintain high water quality in the lake and its tributaries, providing important benefits for the common loon and its prey species. View more information on habitat protection.

Aquatic and Riparian Habitat Restoration
Stream habitat restoration includes replacing large woody debris (LWD) in streams that flow into Chester Morse Lake. LWD is a critical habitat element for fish that spawn in these streams, and fish are a primary food source for common loons. Riparian habitat enhancement projects include planting conifer trees in areas with few or no conifers, releasing existing conifers in areas where they are being suppressed by dense overstory alder trees, and thinning in dense conifer stands. All of these techniques should accelerate development of the large trees that eventually will provide LWD for the streams. View more information on our aquatic and riparian habitat restoration program

Road Improvements and Decommissioning
Roads contributing sediment to Chester Morse Lake or its tributaries are decommissioned or improved to create better habitat for all aquatic species and improve water quality. These improvements should benefit common loon and their prey. See more information on road improvements and decommissioning


Loon nesting on an artificial nesting platform

Deploying Artificial Loon Nesting Platforms
We deploy artificial loon nesting platforms in each traditional nesting area, if prevailing reservoir levels and seasonal timing are conducive to favorable nesting conditions. Platforms are placed where adjacent topography or vegetation provides protection from the strong wind and large waves that are common on the open lake and that can wash nests from the platforms or change loon nesting behavior.

Research and Monitoring
We are investigating the effect of reservoir management on common loon nest site selection and behavior. Related studies include monitoring the delta plant communities and how they change through time under different management scenarios, and monitoring availability and distribution of loon nesting habitat as scenarios change. View more information on the delta plant community and loon nesting studies.