Feeding wildlife may be a popular way to bring them closer in to view but it can also create unexpected problems. Attracting desirable wildlife through feeding may also attract undesirable wildlife, either to consume what you put out or prey on what you are attracting. Wild animals have a natural fear of humans, and in some cases we have a natural fear of wildlife, that acts to keep us from potentially dangerous interactions. However, routinely accessible food sources, whether intentional or not, may cause wildlife to habituate to the presence of humans, even lose their fear.

Yet, these animals are still wild and still unpredictable. Adult deer are capable of delivering strong and sudden kicks with their front legs, posing a significant risk to humans. Males with antlers not only pose a risk from the antlers but may also be more aggressive due to increased hormones and competition at certain times of year. Coyotes attracted to some food sources, unsealed garbage cans or leftover dog food for example, may then attempt to exploit others such as small pets also found near homes. Their status as a predator, though of primarily small animals, combined with their presence in a neighborhood where children are present can be quite alarming. Corn feeding for certain animals can also attract feral hogs. Once in an area, hogs can do considerable damage to landscaping and natural areas. They are surprisingly powerful for their size and can also be dangerous to humans, especially a sow worried about the safety of her piglets.

Supplemental feeding of wildlife may also perpetuate an out-of-balance ecosystem. In the case of white-tailed deer, they may experience increases in reproductive success from additional food sources that can't continue to be supported by the ecosystem. Yet deer will continue to browse in the preserve, just in greater numbers, consuming acorns and young seedlings, and nibbling buds of new leaves. Even trees able to root sprout succumb to continual browsing that depletes the energy reserve in the roots. Over time, the woodlands become dominated by mature trees with an absence of younger age classes that would normally replace the stand. Further worsening the problem for the deer is the lack of nutritional benefit corn provides them. Their preference for corn over native food sources can be likened to our preference for sweets over vegetables. They will expend energy to reach the corn, yet gain little essential nutrition from it to be healthy. In a depleted state, deer are more susceptible to disease.

Bird feeders can also play a role in ecosystem impacts when they supplement the diets of raccoons, squirrels and jays (both blue and scrub). All of these animals are predatory on the nests of small birds, including the endangered golden-cheeked warbler and black-capped vireo. An alternative is installation of a bird feeder designed to eliminate the access these heavier animals have to the seed.