Sorry for the loss of your craft (and the bird). I have had birds chasing my bird and try to steer away and so far they haven't pressed the point and followed. It might be that you are flying a little too close to their nesting area. I had a flight where a lot of bugs were chasing my Phantom. After I landed I saw they had flown into the props and I had a lot of bug blood to clean off my Phantom
As far as it being in water, there is a chance you can revive it if you find it. Mine saw water three times and came back to life 100% after each, and a good three day drying. I had floatation on mine, so it never did anything other than sit upside down on the surface of the lake, for maybe 2 minutes or so. I think the pressure of going several feet underwater may cause problems. The styro shell I made for mine is working well and only added 3.7 ounces.