BRISTOL, ENGLAND – OCTOBER 28: Squirrel monkeys at Bristol Zoo Gardens investigate a special carved pumpkin that has been left as a special Halloween treat in their enclosure on October 28, 2009 in Bristol, England. The gift of the pumpkin does have a serious side, as they are a great addition to the animals? regular diet as they are high in vitamins, potassium, protein and fibre – as well as being the perfect enrichment toy, as the animals have to delve inside to reach the succulent flesh and plump seeds. (Photo by Matt Cardy/Getty Images)