SHEEP CARCASS AVAILABILITY AND USE BY BALD EAGLES

We studied sheep carcass availability and use by Bald Eagle (Haliaeetu s leucocephalus) in the Willamette Valley, Oregon, during winter 1990. We determined availability of sheep carcasses every 2-4 days along a 65-km transect. Bald Eagle numbers were counted weekly at five communa l roosts. Counts ranged from 13 to 49; immatures consistently outnumbe red adults. We calculated persistence rates of 137 sheep carcasses; th ose <200 m from a road or house were rarely used by eagles and persist ed longer than carcasses farther away. Eagles were feeding on sheep ca rcasses in 83% of feeding observations along the transect and 87% of 2 34 Bald Eagle castings contained wool. However, we found no evidence o f eagle predation on sheep. Availability of sheep carcasses appears to be a primary factor influencing eagle use of the valley in winter. Ou r estimate of available sheep carrion/day was more than sufficient to meet the needs of the eagles wintering in the valley. However, if eagl e numbers continue to increase or if carrion becomes less available, e agles may leave the valley. We recommend that ranchers make carcasses available to eagles away from sources of human disturbance, rather tha n burying them as is currently practiced.