Census shows healthy wild herd at Assateague National Seashore

Assateague Island is currently home to 82 horses, the National Park Service says.

The Maryland herd has 21 stallions and 61 mares, and at least one mare is known to be pregnant, according to a news release.

The park service said it completed its March 2018 census of the wild horses on Assateague Island, which shows the number of horses in the Maryland herd is well within the ideal population range of 80-100. 

Liz Davis, a spokeswoman for the National Park Service at Assateague, confirmed six horse deaths have been documented in 2018 so far, including five mares (T3L, N6EL, M17GM “Dee’s Heart,” X15P and T5AFP “AR Arianna,” and one stallion (N6BMS, “Llama Boy”). 

According to a February Daily Times report, one mare was put down early this year after she became unable to stand. The mare, designated T3L, was known affectionately as "Miss T" and was 31 years old at the time of her death.

All those lost were mature, aged horses who lived out their full lives within the national seashore, the release said.   

The National Park Service completes a full census of the horse population in Maryland six times per year, in February, March, May, July, September and November.  

Managed as a wildlife population, the Assateague horses are free to roam over the approximately 27-mile length of the Maryland portion of the barrier island, and can be difficult to find at times, the park service said. 

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During each census, horses are identified by their distinguishing characteristics, mapped and counted. Individual horses that are not observed during multiple census periods are presumed dead. 

The census seeks to monitor the population dynamics of the horse herd in support of the long-term fertility control program that was initiated in 1994. 

Because the herd is managed as wildlife population, the horses exhibit wild behaviors.

"The only thing we manage is birth control," said Davis. 

The contraceptive program was established to ensure the horse population doesn't exceed the capacity of the island or begin to impact native species. It employs a vaccine that prevents pregnancy without changing the horses' hormones and thereby changing social interactions in the herd. The vaccine is delivered via dart gun, thereby avoiding roundups or other handling by humans. 

Veterinary care is not generally provided, because it's a wild herd, Davis said. However, she said, if a horse is injured and it's caused by human activity, the park service does its best to call a vet to see if the injury can be treated.

"Otherwise, let nature take its course," she said. "We will put down horses if they are suffering — if we know about it. Most of 2018 deaths were older horses that died naturally." 

"On Assateague Island in Maryland, within the National Seashore, fertility control was needed as there are no natural horse predators on the island," said Davis. "Otherwise, the horses are unmanaged wildlife." 

However, Davis also said the horses are not receiving contraceptives at this time because the herd is at the low end of the desirable population range.