It comes down to a lot of factors, but a big one is the diversity of funding sources. If you study a species that doesn't have broad appeal, you're probably looking at NSF funding, maybe USDA. If you study a game animal you can tap into all sorts of funding sources, like Ducks Unlimited, etc. You might be able to get state or federal wildlife agency funding. You might get a weird, wealthy donor who like sharks.

NSF grants are still the most important and impressive for most subfields within ecology, but the competition is fierce.