Surrogate Squirrel Monkey mother Louise Grossfeldt looks at baby Loki which sucks its thumb after feeding time at Taronga Zoo in Sydney January 19, 2006. Primate expert Grossfeldt has been hand rearing the baby monkey since the mother died shortly after giving birth. Squirrel Monkeys, native to South America, are not endangered but are threatened by deforestation and are captured as part of the pet trade and for medical research. REUTERS/Will Burgess