ASSATEAGUE – National Parks Service officials this week announced a final management plan to reduce the size of the herd of feral horses on Assateague, choosing an option that includes intensifying the existing contraception program and other measures over a possible removal of some of the beloved ponies from the island.
Two years ago, National Parks Service (NPS) officials announced they were seeking a better way to achieve a balance between keeping the Assateague horses healthy and roaming free while protecting the unique natural environment of their island home. The existing herd, believed to be descendants of horses that arrived on the barrier island some 300 years ago, has proliferated to the point it is having an adverse effect on other natural resources on Assateague.
The current wild horse population on the island is estimated at around 130, but NPS officials last year embarked on an effort to identify a plan to reduce their numbers to a range of 80-100. Several alternatives were suggested including a one-time capture and removal of selected feral horses from the barrier island to reach the target number. Under the plan, feral horses selected for removal would be dispersed either through an adoption program or to a horse sanctuary.
This week, however, NPS officials announced a less severe alternative has been chosen to achieve the desired results of reducing the size of the herd. It includes intensifying the existing contraception program for the horses, which, coupled with natural mortality, will gradually reduce the size of the existing herd to the desired number over a period of five to eight years.
“The way we looked at it, we accomplished two things with this proposed action,” said Assateague Island National Seashore Acting-Superintendent Carl Zimmerman. “We managed to find a way to effectively reduce the size of the herd over a period of time to the desired range of about 80 to 100 horses while ensuring their long time viability on the island.”
In 1985, when the need to begin managing the size of the herd became apparent, NPS officials conducted research on the possible use of a contraceptive vaccine on the wild horses to control their population growth and the vaccine program has been used to manage the size of the herd since 1994. The contraception program worked to some degree, but the size of the herd continued to increase to a peak of around 175 horses in 2001.
As the herd size expanded, park managers observed increasing evidence of resource damage caused by the feral horses, necessitating the effort to examine anew several proposals for controlling the population. This week, NPS officials announced the selected alternative will include an intensified use of contraceptives acting in concert with natural mortality. While the selected alternative will take a longer period of time to reach the desired target of 80-100 horses, it was chosen over the more drastic quick approach of selecting some of the wild ponies for removal from the island.
Future removals of some feral horses was removed from the selected alternative for a variety of reasons not the least of which was the public outcry over the proposal. The majority of the comments received during the public review segment of the proposed alternatives expressed strong disapproval of any action resulting in the removal of horses.
“That alternative was on the table, at least in the initial proposal, but it was decided that wasn’t the best approach,” said Zimmerman. “Folks just didn’t care for that option and we decided to mover forward with the intensified contraceptive program coupled with other measures.
The stated goal of the selected alternative is to manage the feral horses in a manner that protects both the long-term health and viability of the population as well as the barrier island ecosystem that supports them. Under the selected alternative announced this week, NPS officials will continue to monitor the status and trends of the horse population on the island in order to guide herd management and assess the health of the population including monitoring birth and mortality rates, contraception success and a variety of other factors. It continues the existing monitoring program and establishes new monitoring efforts to document and assess the effects of the slowly decreasing herd size.
According to Zimmerman, the intent is to maintain a healthy, smaller population of around 80-100 horses. If reducing the size of the herd compromises its ability to reproduce or creates other unintended side effects such as altering the genetics of the horses through inbreeding, it remains possible small numbers of compatible horses could be added to the population in the future.
Of course, a secondary goal of the plan is to maintain the public’s ability to enjoy the wild pony population on the island and NPS officials are keenly aware reducing the size of the herd to the target range of 80-100 will decrease the number of feral horses potentially available for viewing by the visiting public.
To that end, the selected alternative includes a plan to mitigate the potential impacts by developing improved information and guidance on how to find and view the horses in the national seashore and the state park. In addition, the proposal includes a plan to develop a new observation platform adjacent to the visitor use area that will improve opportunities to see the horses over a wider area than is currently possible.