Wildlife in Arma 3 seems pretty bland, there are few creatures to place in the editor and so little things that they do.
I've compiled a list of features and content that I would like to see in Arma 3. Hopefully you guys could add some of these in the expansion.

• Cattle/cows. I think I've come across some cattle road signs on Altis. It kinda doesn't make sense that you don't actually see any at all!
• Dangerous animals. Say your going 'hunting' out in the wilderness of Altis. Wouldn't it be a lot more authentic if you had to watch out for animals that would hunt you? These animals would probably be great white sharks, static snakes that would bite you if you got near, and some others that I can't think of
• Birds other than seagulls. Seeing flocks of birds flying away after gunshots, birds in trees, birds in nests, etc would make this game seem a lot more atmospheric and alive.
• Modules. Like the ambient animals module in Arma 2.
• Animals that react to human presence or gunfire.
• Bigger variety of animals in general.
• Ability to spawn them without modules. For some reason the only animal you can do this with is the rabbit.