Species: Equus caballus
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
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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.