We plow up native plants to grow miles and miles of single crops like corn and wheat. We drain rivers to bring water to our crops, and many of our farming methods strip the soil of its nutrients and microbes. We pave meadows to make streets and parking lots. As we're busting around making these "developments," we destroy animals' habitats and pollute the natural landscape with petroleum products, pesticides, and other chemicals. These actions kill some species outright and push others into areas where they can't find the food and shelter they need to survive. Often, when one animal suffers from human encroachment, it affects many other species in its food web, so more than one species' population begins to decline. Habitat destruction is the most critical factor affecting the endangerment of species.