OCEAN CITY — While far from the most glamorous aspect of managing the wild horses on Assateague, National Park Service staffers this month began the annual chore of conducting pregnancy tests on many of the mares in the herd on the barrier island.
Each November, Assateague Island National Seashore biologists conduct pregnancy tests on most of the mares among the population of wild horses on the Maryland side in an attempt to predict how many, if any, new foals are expected in the coming year. While it doesn’t sound scientific, staffers follow the mares and wait for them to defecate.
Samples are collected, frozen and sent to a lab to be analyzed to determine which if any of the mares will be expecting next spring. Last year, eight mares were determined to be expecting in what was the largest number ever in the history of collecting the data.
For over two decades, Assateague staffers have been monitoring the birthing habits of the island’s most famed residents and the information collected this month, or more specifically the fecal matter, will tell the story for the coming year.
Employees know the mares in the herd by their alpha-numeric name, their markings, the bands they belong to and the areas of the island they tend to frequent. Although it is not entirely scientific, the pregnancy tests generally serve as a good barometer for the expected foals in the next year.
It is not infallible, however, and every once in a while, there are surprise births on the island. The popular horses on Assateague are wild animals and generally left to the whims of nature. However, in the interest of maintaining a healthy population size, the National Park Service several years ago began a contraceptive program for the mares. In almost each year since, selected mares have been injected, or darted more appropriately, with a non-invasive contraceptive called PZP in an effort to maintain the size of the herd on the Maryland side in its manageable threshold.
The target range for the horse population on the Maryland side of Assateague is 80-100 and there were times over the years when the population was well north of those numbers. In recent years, due to the contraceptive management program and the loss of some horses to old age, attrition and death, often natural and occasionally from man-made causes such as vehicle collisions, the population had dipped.
In the last available census, the population of wild horses on the Maryland side of Assateague had dropped to 73, or well below the 80-100 ideal threshold. However, that census did not include the foal boom on the barrier island this year with eight mares expecting. As a result, the National Park Service’s contraceptive program has shifted to an adaptive management phase.
With no mares contracepted last year, there could be another boom on the island next year and the pregnancy test samples collected this month will predict that.
Meanwhile, the Assateague Island Alliance, or the friends group of Assateague Island National Seashore, which advocates on behalf of the wild horses, in early December will be holding a Name Those Foals raffle, during which the lucky ticket holders will be afforded the naming rights to the last two colts born this year on the island. The tickets are $10 and must be purchased before midnight on Dec. 10. The AIA will hold a Facebook live drawing of the winner the following day on Dec. 11 at a time and location to be determined as the raffle draws nearer.