Bald Eagle perched in cottonwood tree above Fernhill Wetlands on 27 November 2003. Photo by Greg Gillson. Click for larger view.
Written by Greg Gillson on February 14, 2004.
The number of nesting pairs of Bald Eagles in Oregon dropped steadily in the 20th century through the 1970's, to a low of about 56 nesting pairs state-wide. The prime causes were habitat loss (cutting of nest trees), persecution (shooting, trapping, poisoning), and the application of DDT on forested lands to curb insect infestations from 1945 to 1974. Since the late 1970's the Oregon breeding population has doubled every decade. There were 393 known nesting pairs in Oregon in 2001. The population is expected to keep increasing for several years yet.
Wildlife Biologists are understandably cautious about making known to the public the location of nests of birds of prey, as these birds occasionally are still shot, or trapped for falconry. They also can be sensitive to human disturbance. There are publicly-known Bald Eagle nests at Jackson Bottom, Hillsboro, near Fernhill Wetlands, Forest Grove, and above Hagg Lake. Eagles can be found year-round in these areas. Besides these resident pairs, younger eagles and migrants from the north also winter near these bodies of water. Here they find large numbers of fish or ducks to feed upon. Bald Eagles generally take dying animals, such as salmon or carp after they spawn, as well as ducks that tend to become ill in autumn and winter when they flock together in large groups.
Bald Eagles tend nests from February into August. The eggs hatch between late March to late May. After this, adults can be seen tending the young and bringing them food. Most-often, though, adults are spotted perched in tall cottonwoods or other large trees with a view of the water.
In Hillsboro, at Jackson Bottom Wetlands, the large platform nest--6 feet across--is fairly obvious in the grove of oaks just east of the North Viewstand. Binoculars or a spotting scope give excellent views in early spring. By June, though, the leaves on the oak trees often conceal the birds and nest.
The resident eagles may spend much time perched motionless in tall trees at Jackson Bottom. However, they become more territorial in spring and fly forth to challenge any other eagles that enter their territory. The adults engage in aerial courtship displays together in early spring. In summer, they may be seen in the air teaching the young to hunt.
The eagles at Fernhill Wetlands, in Forest Grove, nest on private farm property about 1/2 mile from the wetlands. However, they spend most of the day at Fernhill Wetlands, and are easily seen. When they fly across the ponds, the wildfowl take to noisy flight en masse.