This paper appears to confirm birds are not effected by radar.
http://jeb.biologists.org/cgi/reprint/202/9/1015.pdf
BEHAVIOUR OF MIGRATING BIRDS EXPOSED TO X-BAND RADAR AND A BRIGHT
LIGHT BEAM
The Journal of Experimental Biology 202, 1015ñ1022 (1999)
BRUNO BRUDERER*, DIETER PETER AND THOMAS STEURI
Swiss Ornithological Institute, CH-6204 Sempach, Switzerland
"Switching the radar transmission on and off, while continuing to track selected bird targets using a passive infrared camera during the switch-off phases of the radar, showed no difference in the birds behaviour with and without incident radar waves."