Why do pirates have parrots on their shoulders?
Seafarers in the tropics commonly brought home exotic fauna as souvenirs. Parrots were particularly popular because they were colorful, could be taught to speak, and were easier to care for than, say, monkeys. (Read: they crapped everywhere but at least wouldn’t throw it at you.) They also fetched a good price back in London. However, one can’t imagine a crewman actually heaving at the capstan with a bird perched on him.