Assateague celebrates new foal, tests for pregnant mares

As one new foal is born, Assateague Island National Seashore is on the lookout for more in the near future.

The filly, known as N2BHS-JQ until it is given a more formal name, was born mid-November to a mare named Shasta, just as officials on the seashore begin testing the other mares on the island for pregnancy. She is the fourth foal this year.

Kelly Taylor, assistant public information officer for the seashore, said testing for pregnancy in horses isn't quite as simple as it is for humans.

"While humans might just urinate on a stick, we can't exactly do that with the horses," Taylor said. "So instead, we collect fecal samples and send them off to a lab that tests for the pregnancy hormone. It's very similar."

As the horses are not constantly monitored, it can be hard to say with any certainty when a foal may have been conceived. There's no set season that foals may be conceived or born, but on the seashore tests the horses in November as there are fewer bugs and plants to get in the way. The results will likely be in around the new year.

Even if there are positive results, it can be hard to use those results to predict how many foals will be born.

The pregnancy hormone in horses only appears in their fecal matter for a limited period of time before leveling off and no longer showing up. That could mean that if there was, say, three positive pregnancy tests, there very well could be more than three foals.

Taylor said the target population for the horses is between 80 and 100. A population of that size provides enough genetic variation for the population to remain viable without creating too much impact on the vegetation and habitat of the island.

The most recent horse census, conducted in November, showed the population of the Maryland herd to be at 78 horses — 21 stallions and 57 mares. 

The wild horse management program on the island provides the mares two years or older on the island with contraception in the form of a dart that is shot from 25 to 50 meters away. The dart helps mares form antibodies that prevent contraception.

It's proved effective for the horses both in controlling the population and in protecting the horses. The horses are able to live longer because they don't have the strain on their bodies of multiple births at a young age. 

"The average age of the horses is in the mid-20s," Taylor said. "The oldest one is in her 30s."

Horses that aren't seen for multiple censuses are presumed dead. In this census, two horses were determined to have died: Samantha, who was 26 years old, and Sierra, who was 27. The next horse census will be in February.

The horses in Maryland are treated just like any other animal on the island and often go quite a while without interacting with people. That is a slight departure from the Chincoteague ponies, which are monitored by the Chincoteague Volunteer Fire Company and participate in the pony swim each year.

Reach reporter Hayley Harding via email at hharding@delmarvanow.com or on Twitter @Hayley__Harding.

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