The field of wildlife rehabilitation varies from small scale operations of individuals working from their homes, usually working with a veterinarian; to professionally staffed wildlife hospitals. Some organizations are teaching wildlife hospitals: Tristate Bird Rescue, Paws Wildlife Center, the Wildlife Center of Virginia, and The Clinic for Rehabilitation of Wildlife provide training to veterinary students from around the world, and offer one-year postdoctoral internships in clinical wildlife medicine. Other facilities are affiliated with universities, such as the Amos Rehabilitation Keep (ARK) at the University of Texas Marine Science Institute.