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Where do the wild horses find water on the island?
There are approximately 42 ponds on the Maryland portion of Assateague Island, and during a rainy period there are countless ephemeral pools. That is where the wild horses find their water year-round, as well as every other type of wildlife. During the summer, well-meaning visitors often turn on a spigot to give the horses water. Please call a ranger if you see this happening. Again, while one thinks they are doing the horse a favor, it contributes to changing their behavior in a negative way. Often, horses trying to get access to the "free drink" become aggressive, kicking and biting each other and, quite possibly, a human trying to “help them out.” The wild horses do quite well on the island without human intervention, surviving for well over 300 years. Help us keep them wild, will you?

How Horses Adapt to Winter
Left to adapt to their environment, Assateague horses must create their own protection, and a horse’s winter coat is a remarkably protective feature. The coat starts to grow long before the cold days of winter. As the days began to shorten and the retinas receive fewer hours of sunlight each day, the brain is stimulated to release extra melatonin, a hormone that prompts the hair follicles to produce more hair. You may notice that the horses’ winter coats appear to be fluffy. This is because the hairs lift up to trap warm air, creating insulation, much like a bird creates insulation by fluffing its feathers. Even more incredible…the long outer hairs form channels that help repel water. And if you separate those hairs, underneath there is a layer of dry hair and skin. Pretty Amazing!

Whenever severe weather threatens Assateague Island National Seashore, we inevitably get asked the question "how will the horses survive the storm?". Generally, the Assateague horses retreat from the developed areas of the park to spend the cooler months in the bayside marshes where their preferred forage, Spartina alterniflora (Saltmarsh Cordgrass), grows abundantly. And what in the world do they do when a hurricane or nor'easter strikes? Believe it or not, it's not such a big deal to them (especially when compared to the heat, drought and insects they have to deal with in the summer). During extreme weather conditions they find shelter from high winds and storms by temporarily retreating from the marshes to forested or densely vegetated areas and turning their tails to the wind. 

Why do foals sometimes have a mask like Batman or Batgirl?
People often ask if there is something wrong with the foals when they have mostly black hair around their eyes, wondering if they have a skin condition based on their appearance. So why do they have those rings around their eyes and muzzle? Rest assured, no skin condition. They are shedding the soft and fluffy foal coat, and the new, sleek adult coat is darker and smoother. They shed around the eyes and muzzle first, and gradually the rest of it will be replaced.

Kieper Numbers
Every horse in the Maryland herd is given an alphanumeric code, such as those of the horse pictures here from left N6BM, N6BMT (Sonja), N10O (Tipperary), N6BMT-F (Jojo) and N6BMT-FO (Margaret’s Thunder Heart). This image was taken in 2017 and includes four generations! Notice anything about their codes? Maternal lineage is just one thing you can discover by looking closely at the horses alphanumeric code. When researcher Dr. Ronald Keiper began studying the Assateague horses in 1975, he developed a system that could identify, and trace the maternal ancestry of, each individual horse. The system of alpha-numeric identification numbers he came up with are now known as "Keiper numbers" In 1975, there were only 44 horses in three harem bands living on the Maryland portion of Assateague Island. A harem band consists of a dominant stallion and his mares and immature offspring. Each of these bands was designated by the letter M, N or T. The dominant stallion of each band was given the number 1, resulting in Keiper Numbers. M1, N1 and T1 for the stallions. The other horses in each band were numbered consecutively beginning with 2 (M2, M3, T2, etc.). The letters at the end of each horse’s number indicate that particular individual's maternal lineage and their birth years back to the original 1975 study of the horses. At birth, each horse is assigned a Keiper number created by adding the letter for its birth year to its mother's Keiper number. Birth years began in 1976 with A, B for foals born in 1977, C for 1978, up through Z in 2001. At that point the alphabet was started over with a dash in front of the letter, resulting in -A for foals born in 2002. Accordingly, N6BMT-FN was born in 2015 to N6BMT-F; N6BMT-F was born in 2007 to N6BMT; N6BMT was born in 1995 to N6BM; N6BM was born in 1988 to N6B; N6B was born in 1977 to N6. N6 was present in the herd during the initial 1975 survey and so does not have a birth year letter. She was the sixth horse identified in "N" herd. And the "X" horses? During the 1980s, birth records for the herd were not as closely maintained as they are today. By 1990, there were about 25 unidentified, mostly solid-colored horses living on the island that had been born in the mid-1980s. These horses were designated with an "X" and numbered consecutively. Following a complete genetic study of the horses in 2005, correct identification and parentage for most of these “X” horses were determined based on their genotypes. An example is the mare X13, who was confirmed as being N2BH. Five of these “X” horses could not be positively identified, and so they retained their “X” IDs. However, presumed offspring of the “X” mares living at the time of the genetic study were confirmed as descending from these “X” mares, and so were named according to the same protocol as all of the positively identified horses. The stallion X15NY, for example, was born to X15N in 2000; X15N was born in 1989 to X15, who was one of the five “X” individuals living in 2005 who could not be positively identified. A 1976 B 1977 C 1978 D 1979 E 1980 F 1981 G 1982 H 1983 I 1984 J 1985 K 1986 L 1987 M 1988 N 1989 O 1990 P 1991 Q 1992 R 1993 S 1994 T 1995 U 1996 V 1997 W 1998 X 1999 Y 2000 Z 2001 -A 2002 -B 2003 -C 2004 -D 2005 -E 2006 -F 2007 -G 2008 -H 2009 -I 2010 -J 2011 -K 2012 -L 2013 -M 2014 -N 2015 -O 2016 -P 2017 -Q 2018 -R 2019 -S 2020

Curious about Swamp Cancer or Pythiosis?
Many of our Assateague Friends have raised the question about the fungal infection, Pythiosis or "swamp cancer” (not really cancer) in the Maryland herd. There have been no signs of the disease in the Maryland herd and Resource Management staff consistently monitors the horses for any signs and symptoms. Pythiosis thrives in stagnant pools of fresh water and is a naturally occurring pathogen. You may be aware that the two herds of horses are managed very differently on Assateague Island. The Maryland herd is free to roam the entire Maryland section of Assateague and they are able to access many varied sources of fresh water in the back country. Of note is that many of the freshwater ponds in MD often get surrounded by salt water, thereby potentially minimizing the overall risk of phythiosis. There are approximately 42 ponds on the Maryland portion of Assateague Island, and during a rainy period there are countless ephemeral pools. That is where the feral horses find their water year-round, as well as every other type of wildlife. That plus the smaller size of the MD herd both attribute to a much less hospitable environment for swamp cancer. The Chincoteague ponies are kept in grazing compartments on the Virginia portion of Assateague and there is a physical fence at the state line to prevent the two herds from coming in contact.   The National Park service is constantly monitoring the horse population and the horses are managed as a wild herd. If you have questions about this or other items, we encourage you to reach out directly to the Assateague Island National Seashore team. For more information, click here to contact the National Park Service.

A Wink and a Nod (Courtship & Mating)
Horses are referred to as "long-day breeders" because they come into heat (season) as the days increase in length in the spring. The natural breeding season for horses in the Northern Hemisphere is the spring or summer. Light is the controlling factor in causing mares to come into season in the early spring. Some mares, can breed during the winter months, however. The cycle occurs roughly every 19 - 22 days. Mares carry their young (called foals) for approximately 11 months from conception to birth (average range is 320 - 370 days). Horses will curl their upper lip and press it to the back of their nose, which is called the Flehman response (almost as if they are laughing). A stallion will make this face when he examines a mares urine to find out if she is in heat or season. The Flehman response increases the flow of air through the nostrils, which brings the scent openings behind the incisors on the upper palette to the vomeronasal organ. Click here for more information on horse breeding.

Horses or Ponies (Here’s What the National Seashore Believes)
You may notice that the wild horses on Assateague Island National Seashore are often referred to as “ponies” by some. There is even some signage at the State Park that says “ponies.” That being said, the National Seashore refers to them as horses. Here’s why: The short answer is that they are most closely related to horse breeds than pony breeds. Anything less than 14.2 hands (a "hand" is 4", and equines are measured to the top of the shoulder) is generally considered a pony (and the Assateague horses are 12-13 hands); yet there are many, many exceptions. Here are a few examples: Arabians are often less than 14.2, miniature horses are very tiny, and Caspian horses are 12-13 hands, similar to Assateague horses, but they are all still horse breeds. And on the other side, Connemara ponies are often more than 14.2 hands, but are still a pony breed. Many breeds of horses and ponies have been turned out on the island for hundreds of years, and over time, many were left to go feral. The smaller type we see now is what has adapted best to the conditions on the island and to the available forage, surviving and thriving over the years. Genetically they are a smaller animal. Call them horses or ponies, but remember that they are wild and we need your help in keeping them that way by not feeding them, not petting them, moving away from them if they approach you and keeping a distance of at least 40 feet. Every interaction makes a difference! If you see someone breaking the law or doing things that prevent these horses from remaining wild, please contact the ranger station at 410.641.1441.

  • At the first prompt, choose '3'.  That option directs the caller to the visitor contact station.
  • At the second prompt, there are several options:
    Option #2: Law Enforcement Offices
    Option #1: Front Desk
    Option #0: Operator (answered during business hours; reverts to front desk on the weekends)

Keep in mind that these numbers are staffed intermittently throughout the day; there is no guarantee that a call will be answered due to a variety of factors.

Is a horse pregnant or not?
Each November, Assateague Island National Seashore biologists conduct pregnancy tests on the mares among the population of wild horses on the barrier island in an attempt to predict how many, if any, new foals are expected to join the herd in the coming year. Essentially, staffers follow the mares and wait for them to defecate. Samples are collected, frozen and sent to a lab to be analyzed to determine if any of the mares will be expecting next spring. Of course, there could be a surprise or two. For example, in 2019, Susi Solé (N2BHS-M) gave birth to N2BHS-MR (Seases Bay Breeze or "Breezy") in January and it was a complete surprise (albeit, her tummy was very, very round).

Horse Management Program
Click here for more information about Assateague Island National Seashore horse population over the years.