Detection of biological scatters, such as birds and insects, from radar echoes is very important for aviation safety. By discrimination biological scatters from meteorological scatters one can improve VAD wind analyses and precipitation estimates. The obtained knowledge and skills are potentially useful for many other radar data applications. A case study is performed by using a series of data volume scans collected with NEXRAD KTLX and NSSL's S-band polarimetric radar in the spring of 2001. Based on previous studies of radar observations in the presence of birds, migration studies by ornithologists, and our case study, a classification scheme is being developed. The observations by polarimetric radar with more parameters, like differential reflectivity, differential phase, and correlation coefficient can identify birds from weather echoes. This provides a reliable estimation of the ground truth regarding to the presence versus absence of birds and is used to verify our scheme. It will be able to identify birds from NEXRAD data without using radar polarimetry and beneficial for NEXRAD level II data quality control.