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Murrelets in Monument Ridge Wind Farm?

It was a cold and blustery morning at the top of Monument Ridge. EPIC staff were in the field to investigate a proposed wind project, between 45-70 turbines churning out 135 megawatts of power, and their potential impacts to the marbled murrelet. The murrelet, a seabird that lays its eggs on oldgrowth branches, is threatened with extinction because most of its habitat has been logged. Although this project would not cut any murrelet nest trees, the project could still endanger the bird by killing birds as they commute between their inland nest sites and the ocean, where they feed.

Murrelets in the project area are thought to come from nest sites in Humboldt Redwoods State Park and other pockets of residual oldgrowth in the Eel River watershed. Though murrelets often follow river valleys toward the ocean, sometimes they will jump over ridges for a distance-saving detour. Here, the concern is that murrelets from Humboldt Redwoods State Park may follow the Eel River for a time before jumping over Monument Ridge to connect with the Bear River, a more-direct flight path to the ocean.

Terra Gen, the project developer, has recognized the threat, and in response, has begun to study how murrelets use the project site—are there particular areas of high murrelet use, how high are they flying, and how many are making the trip across Monument Ridge. This information, according to Terra Gen, will inform placement of wind turbines to avoid and minimize impacts to the seabird. Using radars adapted from oceangoing vessels, Terra Gen has been scanning the skies for signs of the bird. EPIC was there to check out their survey efforts first hand.

Our first stop was at a trailer perched on Monument Ridge Road, near a low saddle where biologists  suspected that murrelets might jump between the Bear and Eel Rivers. On the trailer were two open array radar units—spinning bars that emit a radiowave that travels at the speed of light until they hit an object and are reflected back to the radar unit, which receives the radiowaves and locates the object. One of the radar arrays was parallel to the ground, in a way that you might see on the mast of a ship in Humboldt Bay. This radar was to pick up where the birds were flying—did they preferentially choose particular areas or were their flight paths random? The second radar array was mounted perpendicular to the ground, sending off radio waves to pick up how high the murrelets flew as they crested the ridge.

The radar is so sensitive that skilled technicians can tell the difference in the birds that they pick up based on the shape of their radar signature and the speed of movement—murrelets, for example, need to constantly pump their wings in flight and produce a fairly large “blip” on the screen and move incredibly fast, up to 100mph.

Though we were there before the break of dawn, survey station monitors were there earlier. Just prior to our arrival the survey station recorded a potential murrelet: a blueish blip on the screen traveling through the project area. Before the sighting is confirmed as a murrelet, the survey team will send its data back to headquarters to look at the flight speed and radar register of the bird.

Our tour took us to other bird survey sites throughout the project, each spaced to provide a cumulative complete look at the ridgeline, to bat survey sites, and to meteorological stations. By the time we left, the cold morning cleared to a sunny September day.

EPIC was pleased to see the science being conducted for the project, although seeing that blip on a September morning was concerning. Murrelets cross the project area ridges to some degree, something that we know based on survey information for a past wind proposal that partly overlapped  the proposed Terra Gen project area. We will soon learn the degree to which they use this site. The best case scenario is that their use of the project area is low but consistent and predictable, which can enable Terra Gen to better avoid or minimize impacts. If murrelets consistently use a particular area of the project for travel, impacts may be avoided or minimized through strategic placement of wind turbines. Or if murrelets consistently move through the project at certain times of day, impacts may be minimized through shutting down spinning turbines at strategic times. The worst case scenario is that murrelets may use the site almost randomly but very frequently, which would make efforts to minimize impacts far more difficult.

Time will tell. The full results of the survey will not be ready for two years, the standard survey protocol time, although preliminary results from the first survey year should be available earlier.


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