SURVEILLANCE-RADAR DATA ON NOCTURNAL BIRD MIGRATION OVER ISRAEL, 1989-1993

The circular-scanning approach radar at the Ben-Gurion International A irport has been a major tool in studying nocturnal migration over Isra el during 1989-1993. Nocturnal migration was studied by photographs of the radar screen. Each photo was a continuous 10-min exposure, taken every half hour, from nightfall to dawn. The photographs allowed deter mination of direction, magnitude, schedule, and velocity of migration. Comparison of results from five years of observations showed that the diurnal and seasonal schedule of nocturnal migration, as well as the variation in direction during the night, exhibit a pattern that repeat s itself yearly.