I hit a seagull last Friday, or rather the seagull hit me. It seemed to be almost head-on and was all over before I had any time to react. The bird suddenly appeared a few feet above the aircraft and dived below and to our left, followed by a loud thud. I assumed it had hit the left wheel, which it had, only just missing the prop arc. My airspeed at the time was 120 knots, and height over the sea was 500 feet between Stronsay and Papa Westray in the Orkneys. Certainly gave us cause for thought. It wasn't part of a flock, just a lone (now late) bird.
Sent the form off today; thanks for the reference and link Vintage ATCO!