Most of the world's animal suffering occurs in nature....

...and while there may be little humans can do now to address the problem, we should remember that it matters. The pain endured by a fish afflicted with parasites or a rat swallowed alive by a snake is no more tolerable than the 'natural' suffering of humans due to malaria, cancer, or starvation. Both deserve our attention.

Is this an argument for environmentalism and wilderness preservation?
No -- wilderness is where most of the world's animal suffering occurs in the first place. Of course, there are also benefits to wilderness, including the moments of happy animal life that it  makes possible. But humans should think carefully about whether, on balance, wilderness contains more suffering or happiness.
When assessing that question, we should bear in mind that most species give birth to hundreds or thousands of offspring at a time, almost all of which die shortly afterwards. Moreover, many adult insects live just a few weeks before dying of dehydration, disease, or entanglement in a spider's web. While it remains an open question whether insects and other small invertebrates can feel pain, many do show chemical and behavioral traits analogous to those that correlate with suffering in humans (see Dawrst, Alan, "Do Insects Feel Pain?" http://www.utilitarian-essays.com/insect-pain.html).

Are you suggesting that we "police nature"?
No -- in many cases, trying to do that would likely cause more harm than good. There may be a few instances, especially where humans already interfere with ecosystems, in which intervention could reduce suffering without much cost. But the vast majority of wilderness suffering is experienced by small animals, most in the oceans, that are hard to reach and help, even if we knew what "helping" them would look like.
Rather than policing nature, we should focus on research into the welfare of animals in the wild -- studying such questions as "Where does sentience begin in the animal kingdom?" and "Do animals experience more suffering than happiness overall?" Doing so would inform policies -- like habitat preservation or, more speculatively, spreading life into space -- which affect the large-scale numbers and types of wild animals that exist. In addition, we ought to encourage the development of technologies that may one day allow our far-future descendants to relieve the suffering of animals in the wild in ways that don't cause ecological catastrophe.

Why is this so important?
Suffering is horrible -- it should not exist. Yet most of the suffering in the world is experienced by wild animals. There are 6.7 billion humans on the planet. The number of animals living on farms is higher: roughly 24 billion land animals. But there are hundreds of billions of wild mammals, birds, and other vertebrates in the wild. And the number of invertebrates, including insects, is orders of magnitude higher: probably a billion billion, or more (see Dawrst, Alan, "How Many Wild Animals Are There?" http://www.utilitarian-essays.com/number-of-wild-animals.html).

What can I do?
Talk with friends and acquaintances about the importance of wild-animal suffering. Challenge the idea that "humans have no obligations to wild animals" or that "respecting nature means accepting the cruelties that it contains." Human afflictions by natural disasters, disease, and famine are all "natural" occurrences as well, yet we don't accept them as "the way things should be" -- rather, we study the situations and develop technologies to address them. The suffering of animals in the wilderness should be no different. Indeed, in view of the scale of the problem, it should be a top human priority.

Further reading
Dawrst, Alan. "The Importance of Wild-Animal Suffering." (http://www.utilitarian-essays.com/suffering-nature.html)
Ng, Yew-Kwang. "Towards Welfare Biology: Evolutionary Economics of Animal Consciousness and Suffering." Biology and Philosophy 10.4 (pp. 255-85), 1995.
Gould, Stephen Jay. "Nonmoral Nature."�Hen's Teeth and Horse's Toes: Further Reflections in Natural History. New York: W. W. Norton, 1994. (http://www.stephenjaygould.org/library/gould_nonmoral.html)

Contact information
Feel free to contact me with your comments, criticisms, and ideas -- or if you'd like to help with the project of encouraging people to think more about the suffering of animals in nature: webmaster@utilitarian-essays.com