S.B.
My son used to get a little upset over that sort of thing too. We have always watched a lot of documentaries like you are talking about watching. As he matured my son seemed to understand it all a little better. If your son doesn't already watch, he'd probably love the PBS show Wild Kratts (it comes on weekdays at 8 and 5 here, not sure about NJ). It's a terrific show about animals. It starts and ends with live action and real animals, but the story is a cartoon. And they explain things like spiders eating insects or vultures eating animal carcasses, but they don't show it. And it's always handled in a kid friendly way. It may help him understand it all better and be less upset by the idea.