Yes, I've heard him. Very nice little detail that adds to the ambiance of the environments. In the midst of carnage on the battlefield, the hoot of an owl is something I take notice of even more so than explosions and irritating kids with their headsets.
And I'm not sure if there have always been birds flying around on BF 3 before this DLC, but the funny thing is that I have often mistaken birds as players parachuting out of air vehicles on Alborz Mountain. It's only when I try to spot and get fuck all in the way results that I feel an idiot. :/
The birds definitely got one over on me there. It'd be funnier if they shit on your head as an added Easter egg.