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The avian predators that account for the largest loss of production at one ODFW facility are the gulls and cormorants inhabiting the area around Wahkeena Pond. These birds have become even more efficient and effective as predators by combining their effort. Hatchery workers have seen cormorants swim under submerged netting in an enclosure at the pond to get to the fish. The cormorants scare fish into unprotected areas where the more numerous gulls can get at them. Some of the more exotic species reported on the questionnaire were ravens, magpies, and starlings. Not commonly known to eat fish, these birds were reported preying on small fish at only a few hatcheries, but they caused little damage. control Measures Frightening Devices Present control measures for avian predators fall into two general categories: frightening devices and physical barriers. Frightening devices are not specific to anyone type of predator. Almost every hatchery has used or presently uses some kind of frightening device. Devices at ODFW facilities now and in the past include: 1. Cracker shells or other explosives, whether exploded by an automatic device at regular intervals or by personnel at random intervals. 2. Strobe lights, drop lights, or rotating beams on timers. 3. Water spray devices that break up the water surface. 4. Balloons painted with eyes that mimic the birds' own predators. 5. Audio alarms such as whistles or distress calls that mimic bird noises. 6. Owl decoys, similar to scarecrows used in farmers fields. 7. Increased human presence. 8. Rock throwing. 9. Combinations of these devices and activities. Every facility admitted that these devices are ineffective or of limited use. Once the birds realize that the devices cannot cause them harm, they ignore them. The devices are most effective when they are used for a limited time, are used in combination, or are moved frequently. The more irregular the 6