Wallabies are found in Hawaii, but they are not native to the islands. Their presence resulted from an accidental introduction rather than natural colonization.
How Wallabies Arrived and Where They Live
The wallabies in Hawaii are brush-tailed rock-wallabies (Petrogale penicillata), a species native to southeastern Australia. They were introduced to the Hawaiian Islands in 1916 on Oahu when a pair escaped from a private zoo in Honolulu after wild dogs tore through their enclosure.
Following their escape, this breeding pair established a small population. These wallabies primarily inhabit the rugged, rocky terrain of Kalihi Valley on Oahu. They prefer cliff areas with ledges, caves, and crevices, which offer shelter and protection, mirroring their natural Australian habitat. While most confirmed sightings are in Kalihi Valley, anecdotal evidence suggests their small population may have expanded into neighboring Nuuanu Valley. These agile creatures are small, weighing between 10 to 15 pounds and standing approximately knee-high.
Ecological Impact in Hawaii
Despite being a non-native species, the brush-tailed rock-wallabies in Hawaii are not considered an invasive threat to the local ecosystem. Unlike many other introduced species in Hawaii, they have not demonstrated widespread negative impacts on native flora or fauna. Their diet consists of non-native plants like guava, ulei berry, and Christmas berry, which limits their direct competition with native herbivores for food resources.
Hawaii’s isolated island ecosystems are particularly vulnerable to introduced species, with many having caused considerable harm to native biodiversity. Species such as feral pigs, goats, mongoose, and certain plants like miconia have significantly altered habitats and threatened endemic species. In contrast, the wallaby population remains contained within specific rocky habitats and has not spread aggressively across the island. Their limited numbers and habitat preference restrict their broader ecological footprint.
Management Efforts and Outlook
The Department of Land and Natural Resources (DLNR) in Hawaii does not actively monitor the wallaby population, because these animals are not considered a threat to the ecosystem. They are classified as protected game mammals, which means hunting, killing, or possessing them is illegal without specific authorization. This contrasts with many other introduced species that are actively managed or eradicated due to their detrimental effects.
Challenges in managing wallaby populations stem from their elusive nature and the rugged, private land they inhabit. Sightings are infrequent, making it difficult to assess their exact numbers, though estimates from past studies ranged from fewer than 100 in the early 1980s to 250-400 individuals in the early 1990s. When a wallaby does wander into a populated area, the DLNR works to return it to its natural habitat, away from human settlements. Given their restricted habitat and perceived lack of negative impact, the outlook suggests that wallabies will likely remain a small, unique component of Oahu’s non-native fauna.