There are many potential reasons why your gerbil might have bitten its sister's tail, including:
* Dominance: Gerbils establish social hierarchies. The dominant gerbil might bite the other's tail as a way of asserting its dominance.
* Stress: If the gerbils are stressed, they may lash out. Overcrowding, loud noises, or changes in their environment can all cause stress.
* Play: Gerbils can sometimes play-bite, but this should be gentle and not cause any injury.
* Health issues: If the gerbil biting the tail is experiencing pain or discomfort, it might bite as a result.
* Territoriality: Gerbils can be territorial, and biting is a way of defending their territory.
What you should do:
1. Monitor the situation: Observe the gerbils to see if the biting continues or if there are any other signs of aggression.
2. Separate them if necessary: If the biting is severe or frequent, you should separate the gerbils to prevent injuries.
3. Consult a veterinarian: If you're concerned about the biting, it's best to take both gerbils to a veterinarian for a checkup. They can determine if there are any underlying medical issues and offer advice on how to prevent further biting.
It's important to understand that even if the biting seems playful, it can still cause injury. Gerbils are small and delicate animals, so it's essential to monitor their behavior and take appropriate steps to prevent any harm.