Strange behavior in animals can be caused by a variety of factors, including illness, injury, environmental factors, and even genetic factors. It is important to observe and document the behavior to determine if it is abnormal or if it is simply part of the animal's natural behavior.

Illness or injury can cause an animal to display unusual behavior. For example, a bird that is suffering from a respiratory infection may exhibit labored breathing, coughing, or sneezing. A dog with a broken leg may limp or refuse to put weight on the affected limb. In some cases, an animal's behavior may change dramatically if it is experiencing pain or discomfort.

Environmental factors can also cause strange behavior in animals. For example, animals that are kept in captivity may exhibit stereotypic behaviors such as pacing, rocking, or self-mutilation. This can be a sign of stress or boredom. Similarly, wild animals may exhibit unusual behavior if they are in an unfamiliar environment or if their habitat has been disturbed.

Genetic factors can also play a role in unusual animal behavior. Some animals may be born with genetic mutations that cause abnormal behavior. For example, cats with a condition called cerebellar hypoplasia may have difficulty with coordination and balance, leading to unusual movements.

Overall, it is important to observe and document unusual behavior in animals to determine if there is an underlying cause that needs to be addressed. If you are concerned about an animal's behavior, it is best to consult with a veterinarian or animal behaviorist for further evaluation and advice.