evidence: In the summer porcupines eat leaves, flowers, berries and grains. In the winter, they eat primarily evergreen needles and the inner bark of trees. [...] If you’re in porcupine habitat keep dogs on leashes. "We are helping our dogs by keeping them on leads. The North American porcupine has very few predators, and a dog doesn’t hold a chance of harming one," Griswold said. [...] Griswold admits she can go on and on about porcupines. She has been educating the public about them for decades. She wants children and adults to appreciate them and realize that they are mostly shy, nonaggressive and harmless.