Category: Status Reports
Published: October 2007
Author(s): Derek W. Stinson, James W. Watson and Kelly R. McAllister
The early summer population of bald eagles when white settlers first arrived in Washington may have been around 8,800 based on presumed habitat condition. Persecution, the cutting of forests, commercial exploitation of salmon runs, and finally the use of DDT reduced the state's population to only 104 known breeding pairs by 1980. Loss of wetlands, contamination of estuaries, and declines in water quality also probably have reduced the carrying capacity for eagles. The erection of >1,000 dams and the introduction of warm water fishes, however, may have added nesting and wintering sites and produced changes in local distribution and abundance of eagles. The population has recovered dramatically with the ban on DDT use after 1972 and increased protection for eagles and eagle habitat. In the past 25 years, the population of nesting bald eagles grew about 9% per year as eagles reoccupied habitat. In 2005, there were 840 occupied nests, and there are some indications that the population may have reached carrying capacity in parts of western Washington. The population may still be increasing in northeastern Washington and along some western Washington rivers. Though the nesting habitat may be near saturation around Puget Sound and other marine coasts, the total late spring/early summer population is expected to continue to grow with an increase in the pool of non-breeding adults until all available food resources are exploited. If there is no decline in the number of nest sites, productivity, or survival, the population may stabilize around 6,000 eagles.
The number of bald eagles detected during winter surveys in eastern Washington doubled between 1975 and 1984. Comprehensive, statewide surveys of wintering eagles from 1982-89 counted 1,000-3,000 eagles in the state. The increasing trends in those surveys and in resident breeding birds predicted a population of 3,200 winter visitors and a total winter population of about 4,500 bald eagles in Washington in the year 2000; this assumed that winter carrying capacity limits have not been reached. Statewide winter counts have not been conducted since 1989, and the carrying capacity is unknown. The number of resident breeders, and trends in localized winter counts suggest that Washington hosts perhaps 3,500 - 4,000 bald eagles each winter. Up to 80% of the eagles seen in mid-winter in Washington consists of migrants, largely from the Canadian provinces and Alaska. Wintering eagles will most benefit from protection of salmon runs and communal roosts, and managing human disturbance at eagle concentration areas.
In the lowlands around Puget Sound, bald eagles nest in small patches of residual large trees and second growth forest. The large trees along shorelines used by eagles are a diminishing resource, as more and more shoreline is dedicated to residential development. Only 1% of the Puget Sound Douglas-fir Zone is found on lands dedicated to the conservation of biodiversity. Conservation of bald eagle nesting habitat is difficult because 80% of the land within Â½ mile of shores is privately owned, and contains desirable view property. Two thirds of the aggregate land within eagle territories and two thirds of eagle nests are on private lands. The state bald eagle protection rule (WAC 232-12-292) requires a management plan for development, forest practices, or potentially disturbing activities on state and private lands near eagle nests and roosts. Over 2,900 management plans have been signed by Washington landowners since 1986. There are indications that some eagles in Washington, and other states, have become fairly tolerant of human activity near nests. Most eagles, particularly those in rural areas, remain rather sensitive to disturbance during nesting.
The U.S. Fish and Wildlife Service removed the bald eagle from the federal list of threatened and endangered species in 2007. Bald eagles and their nests are still protected by the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act. The Bald and Golden Eagle Protection Act also prohibits disturbance or molesting of eagles. Despite state and federal protection, a large percentage of fatalities of adult bald eagles have human related causes, including shooting, poisoning, vehicle collisions, and electrocution, and a black market trade in eagle feathers and parts still exists.
Although the breeding population of bald eagles in Washington has increased dramatically in the past 30 years, most nests are on private lands and only about 10% of eagle nests are on lands dedicated to conservation. Land near shores is highly desirable for residential development and the human population of Washington is expected to increase by 2 million to 7.7 million in the next 20 years, and double to 11 million by 2050. Forest near shores continues to diminish, and the needs of eagles and desires of humans are often in conflict. Without protections of nesting and roosting habitat, the bald eagle could again decline and require re-listing as threatened or endangered in the state.
Although problems still persist, the dramatic increase in bald eagles in Washington suggests that they no longer fit the definition of a threatened species. For these reasons we recommend that the bald eagle be down-listed to sensitive in the State of Washington.