* Identify the animal as a rabbit: The ears are a key feature of a rabbit's appearance, and they make it clear what creature is being depicted.
* Make the rabbit appear more dynamic: Rampant animals are typically depicted in a leaping or charging pose, and the ears help to create a sense of movement and energy.
* Enhance the heraldic design: The long, flowing ears can add visual interest and balance to the overall design of the shield or crest.
While the ears themselves don't have a specific meaning in heraldic terms, the overall rampant posture often symbolizes courage, vigilance, and swiftness.
In short, the ears are there for artistic reasons, to enhance the visual appeal and identify the creature as a rabbit. They don't have a separate, specific meaning like some other heraldic elements might.