The old urban legend surfaces again....
Aircraft weather radar has absolutely no effect on birds. While bird senses are much better than humans, there is just not enough power in the aircraft units for them to sense the waves. Lots of research has been done on this and unless you are talking an AWACS or other very powerful military radars there is no chance this will work. The urban legend flows from some early very powerful military radar systems.
For further information on this issue and strategies to reduce bird strikes go to the Transport Canada website and look for the link to the on-line copy of the book "Sharing the Skies". Yes, I am one of the authors and no I don't get a commission on the sales!
I have worked in this area for years and can assure you that there is no scientific evidence that this works.