The fastest bird is a peregrine falcon, which can dive at up to ~200mph (~350km/h). Your dragon will be going nearly 8 times as fast, which means 82=64 times the drag. You're going to need a far more aerodynamic body and a massive amount of thrust. All that drag also gets turned into heat, so it's a good thing dragons are fireproof.
However, dragons have a key advantage over birds: fire. If your dragon's trachea extends through its body instead of stopping at the lungs (and I can't see how evolution would provide that), then with the proper shape, it could form a crude ramjet. Climb up really high by flapping, dive straight down like a rock, open mouth and burn the air passing through.
This does require an enormous energy input, as in a material fraction of the dragon's weight for a few seconds of full thrust, but if the reason for its voracious appetite was the internal production of something like hydrazine, it might work. (I haven't run the numbers.)
However, with that kind of power available, there's simply no need for supersonic speeds; it could fly around lazily and instantly kill anything in sight just by breathing in its general direction, with far less effort. The challenge would be having enough accuracy and control to merely cook prey instead of reducing it (and everything else nearby) to ashes.