Feral horse seasonal habitat use on a coastal barrier spit

Abstract

Management of feral horses grazing on Atlantic and Gulf coast barrier islands requires information on seasonal habitat preferences and distribution of important forage species to maintain stable populations and prevent destruction of fragile island ecosystems, particularly as coastal development further restricts free range. Counts from seasonal aerial surveys of Currituck Banks, N.C. were used to determine whether particular habitats were used more or less than would be expected by chance. On-ground observations were used to determine the relative intensity of grazing on vegetation by habitat and season. Feral horses showed seasonal preferences for particular forage species and habitat types. Horses grazed upon at least 16 graminoid and 5 forb species across 6 identified habitat types covering 4,619 ha. In late winter, Maritime Forest was used significantly more than expected while Tidal Freshwater Marsh was used less than expected. In spring, all habitats were used in the proportion expected based on availability. In early summer, Wet Grassland was preferentially used while Dry Grassland was preferentially avoided. The relative degree of exposure from wind may explain why horses spent less time than expected in exposed marshes during winter and more time than expected in forest. The availability of fresh water and hydrophytes may explain why horses spent more time than expected in Wet Grassland in summer and less time than expected in Dry Grassland. Seasonal habitat preferences should be considered when managing for ecosystem sustainability of feral horses on barrier islands.