An alerion or martlet is a mythical bird often used in heraldry. A martlet looks similar to the swallow, but has short tufts of feathers in the place of legs. (Swifts have such small legs that they were believed to have none at all.)
The inability of the martlet to land is often seen to symbolize the constant quest for knowledge and learning, as in the arms of Simsbury-based, Westminster School, Worcester College, Oxford, McGill University and the University of Victoria (where the student newspaper is called The Martlet).
It has been suggested that this same restlessness is the reason for the use of the martlet in English heraldry as the cadency mark of the fourth son: the first son inherited the estate, the second and third traditionally went into the Church and the Army, and the fourth had no well-defined place. As the fourth son received no part of the family wealth and had to earn his own, the martlet was also a symbol of hard work, perseverance, and a nomadic household.
- "they have not such use of their feet, as other birds have. And if perchance they fall upon the ground, they cannot raise themselves upon their feet, as others do, and prepare themselves to flight. For this cause they are accustomed to make their nests among rocks and other high places, from whence they may easily take their flight."
Centuries after his death, Edward the Confessor was assigned a coat of arms containing five golden martlets; Richard II of England combined this coat with the Plantagenet arms, and it later became the basis of the arms of Westminster Abbey and Westminster School.
The arms of the Valence earls of Pembroke were orled (bordered) with martlets, and subsequently these are also found in the arms of Pembroke College, Cambridge.
The shield of the county of Sussex, England contains six martlets, said to represent the six traditional rapes (administrative sub-divisions) of the county.