Haleakalā National Park, located on Maui, is a biological sanctuary defined by its volcanic landscape and extreme isolation in the mid-Pacific. Rising to over 10,000 feet, the park’s diverse ecosystems range from arid high-elevation cinder fields to dense, wet tropical rainforests. This geographic remoteness, lying 2,400 miles from the nearest continent, allowed life forms to evolve without common mainland predators and diseases, resulting in a highly specialized collection of life found nowhere else on Earth.
The Endemic Avian Population
Native birds are some of the most visible and celebrated animals within the park, with the Nēnē (Branta sandvicensis), or Hawaiian Goose, being the state’s official bird. This goose is the last remaining of several endemic Hawaiian goose species, having evolved to be a terrestrial bird with reduced webbing on its feet for walking on lava flows. The park was a primary reintroduction site, with a captive propagation program beginning in 1962 that released hundreds of birds into the Haleakalā wilderness. Nēnē are found in the park’s grasslands and shrublands, often between 5,500 and 8,000 feet in elevation.
The forests on the mountain’s windward slopes are home to the Hawaiian honeycreepers, a family of birds that underwent adaptive radiation. The ‘I‘iwi (Drepanis coccinea) is a red bird with black wings and a long, curved bill adapted for sipping nectar from native flowers like the ‘ōhi‘a lehua. The ‘Apapane (Himatione sanguinea), another common honeycreeper, is crimson-colored and is an important pollinator in the park’s high-elevation forests.
These native forest birds are vulnerable due to their lack of defense against introduced diseases, particularly avian malaria spread by the non-native Culex mosquito. Species like the endangered Kiwikiu (Pseudonestor xanthophrys), or Maui Parrotbill, have been pushed to the highest, coldest elevations where mosquitoes cannot survive. As the climate warms, the safe habitat for these specialized birds is shrinking. The ‘Ua‘u (Pterodroma sandwichensis), or Hawaiian Petrel, is an endangered seabird that nests in burrows high within the volcano’s crater.
Unique Invertebrates and Other Native Life
The high-altitude and isolated environment of Haleakalā has fostered the evolution of many invertebrates with unique adaptations. The park is home to the Haleakalā Flightless Moth (Thyrocopa apatela), which has vestigial wings and travels by hopping across the ground. The moth’s caterpillars spin webs in rock crevices to catch wind-blown plant material, an adaptation to the barren alpine desert. Endemic spiders, such as the Hawaiian Wolf Spider (Lycosa hawaiiensis), are the largest native terrestrial predators in the crater, actively hunting prey without building webs.
Other insects demonstrate specific co-evolutionary relationships with native plants. For example, certain species of planthoppers (Nesosydne genus) feed exclusively on members of the Silversword Alliance, including the Haleakalā ‘Āhinahina (Argyroxiphium sandwicense subsp. macrocephalum). The endemic Hawaiian Yellow-faced Bee (Hylaeus spp.) is a solitary native pollinator that helps ensure the reproduction of the park’s flora. An estimated 98% of the native insect species in Hawaiʻi are endemic.
Non-Native and Introduced Species
The arrival of non-native animals poses the greatest threat to the park’s native wildlife. Feral pigs, goats, and deer are ungulates that trample fragile vegetation and root up the ground, leading to soil erosion and the spread of invasive weeds. Feral pigs are particularly damaging, creating “pig-wallows” that become breeding sites for the non-native Culex mosquito, which carries avian malaria to the native birds.
Introduced predators, including the mongoose, feral cats, and various species of rats, actively prey upon native birds and their eggs. Native Hawaiian birds, having evolved without ground predators, are ill-equipped to defend their nests against these non-native mammals. The mongoose, originally brought to control rats, quickly became a threat to ground-nesting birds like the Nēnē and the burrowing Hawaiian Petrel. The combined effects of habitat destruction and predation have severely impacted native animal populations throughout the park.
Conservation and Protection Efforts
The protection of Haleakalā’s wildlife involves a management strategy focused on excluding non-native threats and aiding endangered species recovery. Exclusionary fencing is an effective tool, with miles of perimeter fence constructed to keep feral pigs, goats, and deer out of sensitive native ecosystems. The removal of these ungulates allows the native forest understory and alpine vegetation, such as the Silversword plant, to recover.
Predator control programs are deployed in areas where endangered birds, like the Nēnē and ‘Ua‘u, are known to nest. These efforts focus on trapping and removing introduced predators like cats, rats, and the mongoose to boost nesting success rates. The park also plays a continuing role in the recovery of the Nēnē through captive breeding programs and the creation of safe harbor areas. Scientists are researching methods to combat avian malaria, including the use of Wolbachia-infected mosquitoes, which could reduce the population of the disease-carrying Culex mosquito and open lower-elevation habitats for native forest birds.