RADAR is an acronym for RAdio Detection And Ranging. Radar is basically a radio frequency that is shot through the sky, bounces off a target, and travels back to where it started from. Just like the radio you can tune in your car, radar is emitted on certain frequencies.
Car radios are from 88MHz to 108MHz, ATC radio is from 118MHz to 136MHz. ATC radar for ARTCC's is from 1 to 2 GHz. Some other things in that range include older cordless phones (900MHz), somewhat new cordless phones (2.4GHz), wireless internet routers (2.4GHz), etc...
Humans can hear from 50hertz to a max of 20KHz (20KHz ceiling decreases with age and loud noise exposure). Dogs can hear on higher frequencies. That is why we can blow a dog whistle, and while humans can't hear it, dogs can. Bats can hear the highest of land animals(As far as I know at 60-70KHz) Birds are pretty much on the same frequencies that humans hear. The can hear from about 50hertz to as high as 29KHz. However, this is no where near radar frequencies of 1-2GHz. So the answer to your question is no, radar does not deter birds, at least no more than radio, cordless phones, walkie talkies, or wireless routers.
Now whales can hear anything from 16hertz up to 200KHz. There is a type of frequency that interferes with their hearing called SONAR (SOund Navigation And Ranging). Sonar is most often used on a 192/200KHz frequency (right on the upper edge of whale hearing!). This is generally used because of less interference and can identify targets closer together. There is a sonar that operates at 50KHz (better for deeper depths, more interference), and this interferes with whale hearing, and may deter them.
Ok, sorry for the rant. I am a big radio guy (several of my professional electives in college were about radio). The answer to the question is definately not, radar does not deter birds.
Myth Busted!!!