Why are axis deer considered an invasive species in Hawaii?

Introduction to Axis Deer in Hawaii

Axis deer (Axis axis) were first introduced to Hawaii in 1959 on the island of Kauai, and have since been established on several other islands, including Oahu and Maui. They were brought to the islands as a game species, but their introduction has had devastating consequences for native ecosystems.

Habitat and Diet

Axis deer are adapted to a variety of habitats, from dry forests to wet grasslands, and are highly adaptable to changing environments. They are herbivores, feeding on a wide range of plants, including grasses, leaves, and fruits. In Hawaii, they have been known to feed on native plant species, including ‘āla’a (Metrosideros polymorpha) and ma’o (Clermontia hawaiiensis), as well as crops and landscaping plants.

Impact on Native Species

Axis deer have had a significant impact on native species in Hawaii, including birds, insects, and other small animals. They are known to outcompete native species for resources, and their aggressive behavior has led to conflicts with other wildlife, including native ungulates such as the feral pig. According to a 2019 study, axis deer have been found to alter the composition of native plant species, leading to a decline in biodiversity and ecosystem function. The study also found that axis deer populations can grow at a rate of up to 20% per year, making them a highly invasive species.