Yesterday (4/30) afternoon I observed an osprey land (actually, dive down to and land) on the bald eagle nest on the electrical tower next to one of the Boeing buildings on the Duwamish (the Boeing facility across from the Museum of Flight--the Developmental Center (DC)). The osprey appeared to be "trashing" the eagle nest: tossing nesting material around; feathers and other material over the edge into the wind, etc. Has anyone observed this behavior by an osprey? (I haven't yet checked the literature.)

Background: In Spring 2000, ospreys attempted to nest on the power tower next to the lab building at the Boeing DC facility. The tower is the largest one directly on the east bank of the Duwamish. Two distinct nests were attempted on either side of the central tower: the one on the north side was the most complete. Although I saw an osprey sitting on the nest, I never saw young and the ospreys left the area in September.

In October or November, someone (Seattle City Light??) installed (strapped) a very large wooden box to the top of the north side of the tower and placed the nesting sticks inside (and that's a loooooong way up). I observed eagles at the site over the winter, and nesting and courtship behavior this Spring by the eagles. It appeared they took up residence, and recently, it appeared that an eagle was sitting on the nest, although aperiodically.

When the ospreys showed up in the area in March, there were numerous bald eagle-osprey encounters, including several aerial interactions, all of which were "won" by the eagles. However, I recently saw the ospreys in display over and near the site.

Last week, when the eagles weren't nearby, I saw an osprey fly close to the nest, then fly away. It did this several times but did not land either on the nest or on the tower. Yesterday, however, was a different story.

Denis DeSilvis
Seattle, WA
Denis.Desilvis at PSS.Boeing.com