Washington Department of Fish and Wildlife (WDFW) scientists recently completed a second season of ferruginous hawk nesting surveys, one of several projects under way since 1999 to investigate an apparent decline in the hawk's population.
Using satellite telemetry, WDFW scientists found that many ferruginous hawks, listed as a threatened species by the state, die during their non-breeding period when they leave Washington.
Those that survive return in spring to the same nesting territories in eastern Washington.
The scientist's work is outlined in a new article in WDFW's online Science Magazine on the Internet.
Department scientists said the first season of intensive breeding surveys in 2002 were designed to update historic nesting records and to compare results of air and ground nest observations for efficiency and accuracy.
Unhatched eggs collected during surveys are currently being analyzed to assess levels of contaminants including lead and pesticides.
At two nest sites on the Hanford Reservation in Benton County, nest platforms have been installed on transmission line towers to reduce nestling mortality and improve productivity.
A final report from this satellite project, conducted in cooperation with the Woodland Park Zoo and U.S. Fish and Wildlife Service, is due later this year.