Every month it seems there is some animal story - somewhere - that goes viral and the entire net focuses on. Usually, it's not a happy story. Cecil the Lion was one such case. Marius the Giraffe from Copenhagen was another. Now, it seems, we have the Yellowstone Bison calf.
TL;DR version - some tourists in Yellowstone saw a bison calf and thought it looked cold. So, they caught it and put it in their car and drove off with it. Rangers tried to reintroduce the calf back to a herd unsuccessfully, with the end result that the little fella was euthanized.
Now. never mind that the animal in question was an American bison, a species that ranges up into Alaska and is one cold-hardy beast. Never mind the safety risks of trying to collect a calf from its mother. And never mind what kind of mess a frightened bison calf is going to make in your car. I'm still trying to wrap my head around the fact that anyone thought this was a good idea.
The thing is, though, stuff like this happens all the time. Our zoo has an entire pen filled with white-tailed deer that some well-meaning person found as fawns, assumed were abandoned, and then decided to take home and keep as pets. Just last week, I had someone bring a Canada goose to our zoo asking us to take care of him. I carried him twenty feet out the gate and tossed him in the creek with all of the others. So far, he seems to be doing fine (as in, the other geese have already taught him how to be an asshole).
Wild animals will largely be okay, with or without our intervention. And if they aren't okay, that's fine too. That bison calf, had he actually died of cold, would have provided food for some of Yellowstone's scavengers, such as wolves, coyotes, ravens, or grizzly bears. There are times when intervention is necessary; I'm especially in favor of it if the animal is in a human-caused predicament, or if the species in question is a particularly rare or threatened one. Some people I know have a very hands-off approach, others are very quick to jump in.
In any case, the jumping in (or not) should be done by trained professionals, who can determine what, if any, assistance an animal needs, and can make the proper decision about how it should be handled. Rehab it? Let it go as is? Euthanize? Send it to a zoo or aquarium? Whenever possible, however, our position should be live and let live... or, in some cases, live and let die.