Species: Equus caballus
Subspecies/Breed/Type
Country: United States of America
Region/Province/Range: Georgia – Cumberland Island
Population type: Feral
Estimated Population size: about 170 horses (2010)
Management Authority: Cumberland Island National Seashore National Park Service
Management Practices: Yearly Population Census
Details of Population
Horses have been on Cumberland Island at least since the 1700s. The current population however is likely the result of breeding with post-1900 introductions to the island. Genetic analysis has revealed that the horses on Cumberland Island resemble several current domestic breeds. (Goodloe et al, 1991)
This population is considered feral, free-ranging and unmanaged, with no supplementary feeding or veterinary care.
The park conducts a census every spring to monitor the population. Based on data from the last 12 years, the herd appears to be stable at approximately 175 animals. From 186 horses tallied in 1986, the population grew to about 220 horses in 1990. However, in 1991, 18% of the herd, about 40 horses, died as a result of an outbreak of eastern equine encephalitis. The latest census (2010) accounted for 121 horses. However, it generally considered that a further 50 horses where not accounted for in the 2010 census, and adding these would take the population to about 170 individuals.
Structure and demographics
Cumberland horses live in typical Harem formations and multi-stallion bands (n=37), all female groups (n=2) and a number of bachelor groups (Goodloe 1991). The mares to stallions ratio was 0.6 females:1.0 males (Goodloe 1991; Goodloe et al, 2000). Average multi-stallion band size was 4.6 horses. Up to 32% of the Cumberland Island Population was comprised of Sub-adults. 54% of stallions travelled in bachelor groups (Goodloe 1991; Goodloe et al, 2000)..
Issues worth noting and needed actions
Not applicable.
If you have further information or images you would like to share please contact us by email.
More entries to the Wild Equus Atlas;
Venezuelan Creoles WE – Entry from Dr. Jose Luis Canelon
Pottoka Piornal ponies WE – Entry from Lucy Ress
Pryor Mountain wild horses WE – Entry from Dr. Jason Ransom
McCullough Peaks horses – Entry from Dr. Jason Ransom
Aveto horses (WE) – Entry from Evelina Isola
Galician wild ponies WE – Entry from Dr. Laura Lagos
Namibia Desert horses WE – Entry from Dr. Telané Greyling
Delft Island horses WE – Entry from Wild Equus
Little Book Cliffs Wild Horses WE – Entry from Dr. Jason Ransom
Gower ponies WE – Entry from Jennie Nellist
Baguales WE – Entry from Dr. Victor Moraga and Enrique Zunzunegui
Exmoor Ponies WE – Entry from Sue McGeever
Tornquist feral horses WE – Entry from Dr. Alberto Scorolli
Sabucedo horses WE – Entry from Ivan Sanmartin Eirin
Cumberland Island horses WE – Entry from Wild Equus
Feral horses of Cotopaxi WE – Entry from Javier Solis Méndez, Lucy Rees, Johanna Marlès and Juan Bermeo
Please share this initiative far and wide. Gracias!
This is an ongoing work, and as such, will be updated regularly as new information is made available.
Bibliography:
Goodloe, R. B. (1991) Immunocontraception, genetic management, and demography of feral horses on four eastern U.S. barrier islands. Ph.D. Thesis, Univ. Georgia, Athens. 150Pp
Goodloe, R. B. et al. (1991) Genetic Variation and its management applications in Eastern U.S. feral horses. J. Wildl. Manage. 55(3)
Goodloe, R.B., Warren, R.J., Osborn, D.A., and Hall, C. (2000) Population characteristics of feral horses on Cumberland Island and their management implications. The Journal of Wildlife Management, 64: 114-121.
Turner, M.G. (1987) Effects of grazing by feral horses, clipping, trampling, and burning on a Georgia salt marsh. Estuaries and Coasts, 10: 54-60.
Turner, M.G. (1988) Simulation and management implications of feral horse grazing on Cumberland Island, Georgia. J. Range Manage. 41:441- 447.
Further reading:
Position Paper: Wetland Impacts from Feral Horses, Cumberland Island National Shoreline
Wild Horses in a Georgia Wilderness? Cumberland Island National Seashore Completes Annual Count
Feral animals on Cumberland Island
Ethology - Wild Equus - Horses - Behavior 
“The mares to stallions ratio was 0.6 females:1.0 males” – What is the value of expressing this data like this? Does this mean that about 70% of the horses of the horses in the entire herd are male? Or does it mean that within the bands, there are almost always two males for every female?
The values are for male to female ratios of the whole island population. Band composition is harem or multi-stallion type, surplus males wandering in temporal assemblages.