What do humans do to harm natural habitats?

Humans do many things to harm the natural environment:

They cut down trees for fuel and material, leaving many animals with loss of habitat (deforestation), leading to floods (trees have a large intake of water, and without them the ground can become saturated) and of course the greenhouse effect, which is, in the long run, flooding all of these habitats via rising sea levels.

The amount of waste materials humans produce is also enormous, Antarctica for example has been martyred for being the last great wilderness, and you can find cruise ships going there from the Caribbean! But where do they dump the waste? Not Antarctica itself, but you can find similar wildlife on many of the surrounding islands.

Leading on from Antarctica, the polar ice caps are melting, meaning a loss of habitat for all Arctic animals.

I cannot go into enough depth about water in rivers being polluted.

As cities grow and more land is used, environments are destroyed along the way.

Ever heard of DDT? Used in the 60s-70s, it is a pesticide used to kill off insects. However, it was not biodegradable (did not decay) and entered the food chain when it was washed into lakes or rivers.

Through bio-accumulation (if the bottom animal in the food chain have a little bit of poison, then the next will eat several of them and have a bit more poison) the population of major bird in Britain and Europe drastically decreased.

In Australia Cane Toads are one of the biggest problems.