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Predator losses of endangered species in reintroduction programs are unacceptable because of the scarcity of the species and the major commitment of staff time and funds. When the whooping crane (Grus americana) cross-fostering experiment (experiment) at Grays Lake National Wildlife Refuge (Grays Lake), Idaho was proposed in 1972, animal damage control (ADC) was considered unnecessary. Sandhill crane (G. canadensis tabida) nest success was high and coyotes (Canis latrans) and red foxes (Vulpes Vulpes) were uncommon. Canids increased by the mid-1970's destroying whooping crane eggs and chicks. An ADC program initiated in 1976 has evolved into a major part of the experiment. The ADC program is costly and complex, requiring several permits and coordination among 5 state and federal agencies and 20+ private landowners. Current ADC effort uses several control methods and annually entails 40± hrs of helicopter time, 900± hrs of staff time and over 9600 km of vehicle use. Between 1975-84, 14 eggs and 23 to 58 flightless young whoopers were lost to predators, primarily coyotes. From 1976-84, 633 predators were removed from the control area; 72% were canids. The ADC program appears to have reduced predation on whooping crane eggs and chicks. Our experience at Grays Lake indicates that endangered species introduction programs should include ADC evaluations in preliminary planning processes.