A sequence of radar images containing birdflock targets was obtained by using a self-development BirdDetection radar system (BDRS) for predicting Bird strikehazard (BSH) applications. We modified standard marineradar to establish the system. Bird flock targets were separated from complicated radar images mainly based on Principal component analysis (PCA) and mathematical morphology. PCA was used to reject the background from theimage sequence, and morphology was applied for marginalde-noising. After mass center of bird flock target in everyimage was calculated, a flight path was detected approximately by data regression algorithm.