If humans have altered that natural environment, describe the changes made by humans and their impact on the species.

The humans are the biggest factor when it comes to the change of the environment in the past few centuries. That process had started much earlier in the human history, but it intensified significantly with the much increased population in the settling of pretty much all of the planet.

The humans are destroying large portions of the environment for their own interests and gains (at least for now). That has resulted in the loss of full ecosystems across the planet. Lot of species have gone extinct because they lost their habitat, and much more are on the verge of extinction because of it.

Also, the hunting of the animals, especially without any reason, but just for fun and having trophies, or because of misinterpreting things, have resulted in a direct extermination of the species, though their environment was still there.