Eagles have returned to the Nooksack in droves; why their future could be at risk

The number of bald eagles seen around Deming in the last 50 years has sextupled, a trend that persists all along the Nooksack River.

Past studies in the area have shown only about 100 bald eagles in an 18-mile stretch of the Nooksack River, but that number has ballooned to nearly 600, according to a just-published study.

The independent study, titled Spatiotemporal Responses of Wintering Bald Eagles to Changes in Salmon Carcass Availability in the Pacific Northwest, was conducted by Ethan Duvall, a graduate student at Cornell University in Ithaca, New York. The study is available through the Northwest Scientific Association. 

Duvall spent two winters trekking along the Nooksack River, beginning the study during his time at Western Washington University. While hiking in the cold months, he counted the bald eagles in the area and monitored what they ate.

Duvall said there were clear connections between the availability of chum salmon remains and the response of bald eagles. One limiting factor is the amount of total salmon available, and in rivers like the Skagit, this could drive eagles to rivers with more stable salmon populations like the Nooksack.

But, this is not the most important factor. Duvall said a more "ubiquitous" concern was climate change and how that affects salmon migration and water flow.

See the study here: https://doi.org/10.3955/046.095.0306