Jonah's Albatross
When sailors who ply the Sea of Rust put in to port, the first thing they usually do is purchase a fistful of lucky charms and trinkets. When the crew next gather to set sail, whether it be to haul cargo to the Coastal Kingdoms or simply go on an extended fishing trawl, they will present these objects to the captain. Those deemed most auspicious will be nailed to the mast and rails. The rest the sailors can keep for their own protection.
The reason for this strange custom is the Jonah's Albatross. Considered a beast by scholars, this four-winged bird of ill-omen is hated by all seafarers. They are, by some supernatural means, capable of stripping a man of balance and common sense, as well as affecting the laws of probability in an unusual manner. This can cause even an experienced captain to steer through a dangerous reef, or a veteran sailor to lose his sea-legs and go tumbling overboard. Ropes that were sound a moment ago will snap, the wind will gust in just such a way as to carry a man over the rail, and so forth.
Sailors believe that the birds are the spirits of men who have died at sea while neglecting their duties through drunkenness, idleness or foolishness. They seem not to eat fish, instead feeding exclusively on the carrion of those poor fools who die as a result of their influence. The superstition goes that someone who perishes this way will themselves return as an Albatross and haunt the ship they sailed on. This in turn has led to the practice of renaming and repainting a ship if there is a death on board, regardless of the cause.
The only proof against these cursed creatures is to find a way to drive them far enough away that they can no longer exert their baleful influence. Brandishing a genuinely lucky item at them is considered to be the easiest way to do this, as they cannot stand such things. Many a voyage which has been plagued by these beasts has ended with the captain returning to port and exacting vengeance on some poor pedlar when his charms have proven ineffective.
Extract from 'Odd Customs and Habits of the World' – Capital Press