Can deer be dangerous? Yes. People who think campground deer are tame may find that they can attack suddenly. A woman trying to feed apple slices to a deer was hospitalized after a buck tossed her into the air on his antlers, breaking her tailbone. I have heard of someone trying to put a child on the back of an elk, thinking that wildlife in parks must be tame.
Attracting deer also may attract animals that prey on deer. A wildlife officer was called to a home in the Sierra foothills where a mountain lion had been seen several times. He learned that the residents had put a salt lick on their porch. Placing salt blocks out for deer is illegal under the 1996 state regulation prohibiting big game feeding (Title 14, California Code of Regulations, Sec. 251.3). The mountain lion's main food is deer. By routinely bringing in deer, you may attract mountain lions.
The key point in all this is that animals that become habituated to human feeding change their behavior. In Los Angeles recently, a child in Griffith Park was severely bitten by one of a number of coyotes that had become accustomed to being fed and had acquired the dangerous habit of coming too close to people. Years before in Los Angeles, another child was dragged from her yard and killed by a coyote emboldened by feeding. A child might mistake a coyote for a dog and move in to pet it. In some situations a coyote might mistake a small human child for a prey animal, though coyotes do not normally attack humans.
"Bear problems" have increased as more people have moved into bear habitat. Often, people feed bears inadvertently by failing to close garbage can lids securely, or worse, give them handouts. Sometimes such bears must be killed, simply because people who live in or near bear habitat do not recognize their responsibility to make sure they don't attract bears in the first place.
Each time a human being is injured by a wild animal there is an outcry, with people demanding that these animals be eradicated. When fed animals become a nuisance, the feeders, or their neighbors, often want someone to relocate the animal in a humane way. This is an unwise and often unauthorized remedy that doesn't solve the real problem, but instead creates new ones--it moves the problem to a different location and puts relocated animals at additional risk in unfamiliar areas. Yet we could easily share our environment with some wild animals if we'd only learn to respect their independence and their wildness.

Must we give up all encounters with wild animals, then? Not at all. The best way to see them and hear them is to walk away from the campground, to walk into a wilderness and just look and listen. (See Hiking by Ear, Listening on Foot for more on listening.) Some people are afraid to do that. They can do it from their cars, sitting quietly, windows open. The car will serve as a blind.
The impulse to offer food is natural. It's called hospitality when we offer it to our own species. It gives us pleasure. But let's not inadvertently kill wildlife with kindness. If we truly care about wild animals we will learn more about them, make sure they have the habitat they need, respect their self-reliance, and spare them our charity.

Ron Jurek is a wildlife biologist in the Nongame Bird and Mammal Conservation Program of the California Department of Fish and Game. He works with the California condor and other endangered and threatened species.