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To develop a bird-avoidance model for Naval Air Facility El Centro, California, we used a modified marine-radar system to quantify nocturnal (sunset to midnight) bird movements in the area. Previous birdradar studies relied on visual monitoring of the radar screen for data collection. This study represents the first use of computer-aided image analysis of marine-radar bird-data. Radar images were automatically captured, analyzed, and archived with a personal computer. The image analysis eliminated ground clutter, calculated the sample area, identified bird targets, and categorized them into three relative size classes. This made data collection more uniform by eliminating observer bias. We operated the system on 34 nights between 20 Oct and 29 Nov 2000 and recorded a total of 320,703 bird targets. Calculated hazard indices ranged from a low of 0.23 to 29.48. Hazard indices < 10.00 were classified as low, between 10.00 and 18.00 were classified as moderate, and > 18.00 were classified as high.