So here we get an admission that you are not a professional zoologist, and despite taking undergraduate classes in zoology, you don't have any experience as a professional zoologist, and aren't in a position to say what they do.
Every famous zoologist widely known to the public* was famous for studying some aspect of animal behavior, which includes population dynamics, distribution, interactions with the environment.
* Jane Goodall, Diane Fossey, Charles Darwin, Alfred Wallace, Richard Dawkins, Farley Mowat.
Carl Linnaeus was famous for classification and taxonomy, but that's just basically accounting, not hard science. If aliens came to earth to study animals, they would come up with their own nomenclature and classification schemes. So classification and taxonomy are just human conventions that don't tell us anything fundamentally real.