The Stillaguamish Watershed supports one of the largest populations of wintering bald eagles in the lower 48 states. Other watersheds with relatively healthy salmon populations (including the Skagit and Nooksack) also provide winter eagle habitat. The Stillaguamish Tribe and The Nature Conservancy have monitored wintering eagles in the Stillaguamish for the past eight years. Past monitoring efforts suggest that they move within and between river drainages in search of new food supplies. Currently, there are no bald eagle monitoring efforts in place in the Stillaguamish due to a change in protection status for the species.
About the Species
In July of 2007 the Bald Eagle was removed from the federal Endangered Species list. Although the Bald Eagle is no longer listed as a State Threatened species, it remains classified by WDFW as a State Sensitive species. Sensitive species are any wildlife species native to the state that are vulnerable or declining and are likely to become Endangered or Threatened in a significant portion of their range within the state without cooperative management or removal of threats. For that reason, cities and counties may continue to protect eagles under local critical areas.
The Local Population
The majority of the Stillaguamish watershed bald eagle population is seasonal. In the winter, large numbers migrate from as far away as Alaska to eat the dead salmon (primarily chum) carcasses that abound in the Stillaguamish River and its tributaries. The best eagle watching season is from late November to late-January with eagle numbers peaking from Christmas through the second week of January. During high flow events or later in winter after salmon carcasses are no longer available, eagles tend to congregate in the lower watershed and target waterfowl and other birds. Most of the river-related feeding activity is concentrated in the morning. When not actively feeding or searching for food, eagles will perch in nearby trees to conserve energy. Bald eagles will also communally roost overnight in the vicinity of a food source.
As dusk approaches, eagles seek out night roosts to perch and take refuge from inclement weather. Roost areas provide thermal and physical protection as well as serve various social functions. Eagles seem to prefer old, large conifers with large limbs and well-developed stand canopies. Deciduous trees are sometimes used in riparian areas depending on weather conditions. Roosting sites are often located on slopes that face away from prevailing winds. There are 14 known communal winter roosts in the Stillaguamish Watershed.
Maintaining regions of mature forest and protecting salmon runs in the Stillaguamish will provide bald eagles with high quality habitat during the critical winter months.