Winter is here and it can be a difficult time for many wildlife species as they try to find food in the cold. However, if you’re visiting any of the US’s multitude of national parks, officials have a clear message for you: don’t feed the animals.

“We want to remind the public that feeding wildlife in the park is not allowed,” the National Park Service said in a recent statement. And by not allowed, they mean illegal – those who are caught get slapped with a $300 fine for breaking federal law.

The main issue here is, contrary to what some people may believe, human food is not healthy for wild animals. If they eat human food, some species can even stop eating the foods that would give them the necessary nutrients to survive, especially if they start to rely on humans and stop hunting or foraging as they would do normally.

In other instances, human food can make animals sick and spread diseases. Dependence on our food can also make some animals more aggressive as they approach people in their search for it, resulting in them being killed to protect the public.

Although it is illegal to feed the animals in the national parks, it is generally a good idea to think carefully about feeding any wild animal anywhere for most of the reasons above. Although most species in other contexts won’t necessarily become an aggressive threat to people, their dependence on and tolerance for our food can be dangerous.

Even feeding ducks at the local pond is not a good idea – but if you do decide to feed them, you really shouldn’t give them bread.