It all depends on what we mean by "think." If you mean making decisions based on evaluating potential dangers and rewards of any given behavioral choice, then of course: every animal thinks, though at varying levels of complexity, depending on the complexity of their lifestyle. Predators (like dogs and cats) obviously need a lot more cognition to survive than vegetarians like cattle, who just munch the grasses in front of them all day, and then go back to the barn at night! Prey animals in the wild, of course, like most birds and small mammals, need a lot more cognitive skills to evade predators than herd animals like cattle or buffalo. But even here, predators--like eagles or wolves, need to be a lot smarter to nab enough prey (all trying to evade them) to feed their babies.

But if by "thinking" you mean verbalizing this process or using symbols like numbers to calculate, then of course humans alone have this ability. But at root we are no different from any other animal: we must eat to survive, identify and avoid potential dangers, compete for the attention of potential mates, then breed, raise, and feed our young. Underneath all our other highfallutin' motives, this is why we do what we do!