In 1778, Captain James Cook’s crew released goats in Hawaii as a future food source; their descendants damaged native plants and worsened erosion

When Captain James Cook anchored off Hawaii in January 1778, he wasn't planning an invasion. He brought his crew, gifts, and a few goats meant as a future food source for sailors and islanders. According to a National Parks Conservation Association feature, Cook visited Hawaii three times, and the first two visits were peaceful trade exchanges. The third ended in violence, and Cook died in the fighting.

Cook's crew released the first goats on Niʻihau on February 1, 1778, a ram and two ewes, and released more the following year at Kealakekua Bay on the Big Island. Captain George Vancouver releases another pair on Kauaʻi on March 13, 1792. According to the NPS historical report, these animals reproduced quickly once they went feral, and their descendants have never fully left the islands since.

Why Hawaii's plants never stood a chance
Hawaii's ecosystems evolved in near-total isolation, with no grazing ungulates present. According to the same NPS report, native plants in the park "had never before encountered mammal predators" and had "either lost, or never developed, adequate defenses such as thorns or an unpalatable taste." Goats also had no natural predators on the islands, so their numbers grew fast. According to the University of Hawaii ecological study, ‘The influence of feral goats on the lowland vegetation in Hawaii Volcanoes National Park,’ the park's coastal grasslands turned out to be entirely goat-altered landscapes. When scientists fenced goats out of test plots, native bunchgrasses and a rare native vine returned within two years, proving the bare terrain was a man-made, or rather goat-made, problem.

The damage climbed from the coast to the mountains
According to the NPS report, feral goat herds had already appeared in large numbers across lowlands, ranchlands, valleys, and uplands by 1850, and were seen as a serious menace to forests and farmland. As numbers grew, goats moved into higher-elevation forests, stripping bark from trees and thinning the canopy. A separate study on koa trees, one of Hawaii's most important native species, found that goat browsing nearly stopped young trees from surviving past a certain height. Research on koa reproduction in the park titled ‘The influence of feral goats on koa (Acacia koa Gray) reproduction in Hawaii Volcanoes National Park’ found that saplings taller than half a meter were almost entirely absent outside fenced areas, while hundreds grew healthy inside protected enclosures. A broader review of the islands' ecosystems backs this up.

According to a peer-reviewed study, ‘Conversion of native terrestrial ecosystems in Hawai‘i to novel grazing systems: a review,’ published in the journal Biological Invasions, introduced grazers like goats have been linked across Hawaii to soil erosion, increased fire risk, and a long-term shift toward non-native grasses.

A century of hunting barely made a dent
Hawaii Volcanoes National Park was established in 1916, and hunting was actually suspended for over a decade afterward. The NPCA feature notes that the territorial government later revived control efforts, eliminating more than 17,000 goats between 1927 and 1931. Progress didn't last. Starting in the mid-1940s, the park hired private companies for shooting drives, a practice halted in 1955 for violating National Park Service policy. For the next 15 years, park staff ran the hunts themselves. Between 1955 and 1970, more than 31,000 goats were killed or removed. Yet by 1970, the park still held roughly 14,000 goats, more than when organized control efforts had first begun in the late 1920s. Goats were simply reproducing faster than anyone could remove them.

Fences finally succeeded where guns had failed
In 1972, park scientists tried a new strategy. According to the same NPCA account, they built goat-proof fences around small sections of the park, let native plants recover inside, then hunted out whatever goats remained trapped there before moving to the next section. It worked. By the early 1980s, after a decade of this fence-then-hunt approach, the park, an area roughly the size of Los Angeles, was free of all but a dozen or so remaining goat bands.

Meet Agent Orange, the goat who turned informant
The last holdout goats were the smartest ones, skilled at avoiding hunters. In April 1981, rangers tried something unusual. According to the NPCA feature, they captured a female goat, marked her with orange paint, and fitted her with a radio collar, nicknaming her Agent Orange. Because goats are social animals, she sought out other goats, revealing hidden herds to rangers. A dozen more collared goats followed as informants, and small teams with rifles, sometimes assisted by helicopter shooters, removed the herds she exposed.

Why this old story still matters today
The battle never fully ended. According to the same source, Hawaii Volcanoes National Park now maintains about 177 miles of boundary and interior fencing, watched over by a dedicated crew of 10 employees who repair breaches after every storm. Haleakalā National Park on Maui adopted the same fencing-and-hunting approach with similar success.

For a generation that cares about climate change and biodiversity, this is a reminder that good intentions don't guarantee good outcomes. One small act of hospitality in 1778 reshaped an island ecosystem for nearly 250 years, and it's still being managed today.