The Big Island of Hawaii showcases vast ecological diversity, hosting 8 of the world’s 13 climate zones, from rainforests to deserts and alpine regions. These varied conditions have fostered unique plant and animal species, many found nowhere else. The island’s isolation also makes its natural systems sensitive to outside influences.
Goat Population and Their Arrival
Goats were introduced to the Hawaiian Islands by European explorers in the late 18th century. Captain James Cook brought goats in 1778 and 1779, with Captain George Vancouver following in 1792 and 1793. Initially, these animals served as a food source for sailors and were gifted to the Hawaiian people. Many domesticated goats soon escaped, establishing feral populations.
Feral goats rapidly proliferated due to a lack of natural predators and abundant habitats. They adapted to various environments, from low elevations to over 9,000 feet, including lava fields and mountain slopes. While a precise island-wide census is challenging, estimates provide insight into their numbers, such as the Hawaiʻi Department of Land and Natural Resources’ estimate of 2,000 wild goats across 100,000 acres on Hawaiʻi Island in 2022. Historical data indicates significant populations, with Hawaii Volcanoes National Park alone having an estimated 15,000 goats in the late 1970s before extensive control efforts.
Ecological Impact and Management
Feral goats have had considerable consequences for the Big Island’s native ecosystems. Hawaiian flora evolved without large grazing mammals, so native plants often lack defenses against herbivory. Goats consume and trample vegetation, leading to environmental degradation, soil erosion, and altered plant communities. This damage promotes the spread of non-native invasive plants, which recover more quickly from grazing than native species.
To mitigate these impacts, various management and control efforts have been implemented. Fencing is a primary strategy, used to exclude goats from sensitive areas and protect native plants. Within fenced enclosures, native species show an immediate positive response and increased survival.
Controlled hunting, including aerial shooting, is another method to reduce goat populations, particularly in remote terrain. Other techniques include snares and “Judas goats,” where radio-collared animals locate and lead control teams to wild herds. These efforts have proven successful in regions like Hawaii Volcanoes National Park, where the goat population was reduced from thousands to fewer than 100 by 2017. Managing feral goat populations remains an ongoing challenge, requiring sustained vigilance and coordinated efforts.