Managing The Ponies
there are actually two herds on assateague island, which are genetically identical. the major difference between the herds is in how they are managed. a fence on the maryland/Virginia border keeps the herds separated.
the Virginia herd is managed by the chincoteague Volunteer fire Department, who organize a yearly pony penning event. some of the ponies are rounded up, driven across the channel on to chincoteague island, and auctioned off to raise money for the continued care of the herd, whose numbers are kept at around 150.
the maryland herd is managed by the National park service. they use birth control to manage the herd size, which is kept at around 90.