Rabbits scream, squeal loudly or whistle when they are hurt or dying or when they are very frightened. Typically, the distress call occurs after an injury, when the animal is sick, or when the animal is trapped or injured by a predator. If the rabbit's ears are back while making the sound, the rabbit is afraid of something in the nearby environment. A growling noise accompanied by tense muscles and an erect tail indicates anger and aggression.
Other stations also prompt sounds that indicate distress, as rabbits use a variety of sounds and body language to communicate. Teeth chattering and thumping the back foot also indicate fear, especially when the rabbit cannot flee. This behavior is typically present when the rabbit is trapped by a predator or another opponent that seems frightening.
Sick rabbits often make sounds to indicate their distress. For instance, a sick rabbit may grind his teeth aggressively, particularly when a dental problem is present, but light tooth-clicking indicates happiness. Sick rabbits also whimper or squeak, and snorting can indicate an upper respiratory infection.
Shivering is typically a sign of happiness rather than a response to fear or illness. Rabbits that feel threatened and are planning to attack often hiss before the attack occurs.