In New England, fruit-eating birds are particularly vulnerable in the winter, because they depend so heavily on a food source that ferments, and to get enough protein they need to eat a lot of it. Toxic levels of ethanol can be produced as the natural sugars ferment, causing some consumers to become inebriated. Robins, waxwings and starlings have been found dead in large flocks after eating toxic berries and diving into the ground or colliding with solid structures. In addition, when they are really drunk, they lose mobility, making them helpless in the presence of predators. To the surprise of many observers, birds that appear lifeless on the ground have been known to eventually sober up and fly away. While birds don’t intentionally wish to ingest a lot of alcohol, there are other animals, such as elephants and apes, that will wander for miles to seek the pleasure of fermented fruits.