How do you make arctic wolves and other things like big cats happy. I get..

The exhibit is either too small or it is over-crowded.It helps to not have to many animals in one exhibit.Sometimes the exhibit is to big.Sometimes there is to much foliage or rocks.

In particular with Arctic Wolves, what I've found that works, is instead of putting several large rocks in their habitat, put about a million of the small snowy rock around the edge of the habitat. The zookeeper will tell you there are too many rocks, but just continue adding them as long as the wolves make happy faces. This will boost your habitat suitability rating, as well.

Also, go to the research and conservation tab and put money into researching animal shelters. Unclick all of the other options for research to accomplish this faster, and spend money until you have earned the snowy cave, which is the wolves preferred shelter. Or, if you don't want to wait and spend the money, name a guest "John Wheeler" to unlock all the animal shelters, and you will have the snowy rock cave in your animal shelters tab.