Are American bulldogs bird dogs

That all depends on a few variables. What type of bird and does the dog hunt naturally.

Most, but not all ABD's have a strong hunt instinct. That instict can be focused on certain birds like pheasants etc.. I would not recomend taking one duck hunting as they are not strong swimmers. I have successfully trained more than one ABD to hunt pheasants. It can be tough to get them to point, they almost always will flush the bird so always be ready. Also, they will try to grab the pheasant before it flies, but I have had that problem with almost every spaniel I have trained. It takes time and pleanty of reinforcement but that's what makes it fun. Bottom line is, you could train a Pom to hunt, but why. get a Spaniel if you're a serious bird hunter.