Well, whether you realize it or not, you are directly contributing to the deaths of all kinds of animals and other living creatures. When that big Combine sweeps through the wheat field to supply the wheat for your bread (or rice or whatever), all kinds of snakes, birds, insects, moles and other creatures are killed in the process. Multiply this by number of vegetarians in the world, and you have hundreds of thousands of dead animals and insects.

When the house or apartment building that you live in was constructed, all kinds of wildlife was killed and/or displaced. As human population continues to grow, that process only continues.

Or consider the water treatment plants, dams, highways, bridges etc. that have been built -- they all result in the deaths of animals and other life forms.

Nearly all human activity results in some life or death impact on the natural world.

Just because you don't eat animals, that does not mean you aren't killing them.

Personally, I don't have a problem with the killing -- it's the immense pain and suffering involved with modern food production. I have no problem killing a bison that grazed its entire life in a field, as long as that process is humane (and it is). I should be so lucky to die such a quick, painless death. Of course modern factory farms are another story altogether.

The bottom line is that life on earth results in the deaths of other living creatures, despite the fact that the ways in which you contribute to such death is not immediately visible.