In our yard there are two trees and a vine that the squirrels love. Fortunately, none of them are usually dangerous for humans. That’s not always the case.
Avocado Tree: Yes and no. The squirrels eat the avocados as they hang on the tree. If we tried that, we’d break our teeth. To be edible by humans, they have to soften, a process that could take several days once they’re picked.
Apricots: This is another yes and no; it depends on which part is eaten. The fruit itself is very healthy for humans. The seeds are not. The seeds are sometimes used to “prevent” cancer. All parts of the apricot tree, including the seed, have a constituent that turns to cyanide in stomach acid. Eat enough of the seeds and you’ll skip cancer…you’ll die from the cyanide.
Grapes: For humans, both the grapes and the leaves are safe to eat, though I don’t recommend filling up on the grapes too often, as it can cause diarrhea. However, should you have pets you may want to keep them away from grapes and raisins. Dogs are particularly sensitive.
Mallow Tree: I did not know that squirrels liked the leaves of mallow trees until I planted one. It makes sense, the mallow family has members used in herbal remedies and many find it sweet. It is hilarious to watch the little varmints strip a branch in ten seconds.
Walnuts: I can attest to the fact that squirrels hide these nuts for winter use. I can also attest to the fact that they frequently forget where they were buried. Each spring we have little walnut trees in areas that are not suitable for a tree.
The meat of the walnut is safe, but the rest of the plant is not. In fact, if you have a walnut tree in your yard, you may notice that some plants can’t even handle the soil around the tree.
Yew Berries: Here, the difference is in teeth. Squirrels don’t grind their food, so they can eat the berries with no problem. However, humans do grind their food, and it only takes a few berries to be deadly.
The best way to make sure you know what to eat and not to eat in wilderness areas is to study and/or ask questions. Books with clear pictures of each plant are very useful. In fact, you may want to include a good herbal remedy book in your studies in case of injury.
As for people, talk to the park rangers. If there are guides around, talk to them, or let them lead you on your adventure. Watching the squirrels really isn’t the best way to determine whether or not you will survive your outing.