Other than the contraceptive and treatment in emergencies, ponies from the Maryland herd are treated much like other wildlife, with no extra attention paid to them by Park Service employees. It is thought likely that the Maryland herd carries equine infectious anemia (EIA); they are effectively quarantined, however, by allowing no riding or camping with privately owned horses along the mainland shore during the insect season which stretches from mid-May to October. Due to their treatment as wild animals, ponies from the Maryland herd can be aggressive, and there have been reports of them tearing down tents and biting, kicking and knocking down visitors. In 2010, after an increase in biting incidents, the National Park Service implemented new measures for educating visitors about the ponies. These measures included new safety information in brochures and recommended viewing distances between the visitors and the ponies. There is also some danger to the ponies from the visitors: ponies have become ill from being fed inappropriate human foods, and on average one Maryland pony a year is killed by a car. Since 1991 there has been a "Pony Patrol", where volunteers on bikes patrol the island, educating visitors about the ponies.