Geckos are a common sight across the Hawaiian Islands. Despite their widespread presence, no gecko species are truly native or endemic to Hawaii. All current populations were introduced through human activity over centuries, not through natural dispersal.
Gecko Species Found in Hawaii
Eight established gecko species are commonly found across the Hawaiian Islands. The Mourning Gecko, Lepidodactylus lugubris, is a small, slender gecko typically gray or tan with dark markings, and is unique for being an all-female species that reproduces asexually through parthenogenesis. The Stump-toed Gecko, Gehyra mutilata, also known as the Pacific Gecko, is a plump, grayish-brown gecko that arrived with early Polynesian voyagers.
The Common House Gecko, Hemidactylus frenatus, is another widely distributed species, easily recognized by its semi-translucent skin and bumpy texture. This nocturnal gecko is known for its distinctive chirping sounds and is believed to have arrived in Hawaii around or after World War II.
The Fox Gecko, Hemidactylus garnotii, is similar in size and shape to the Mourning Gecko and also reproduces asexually. More recently introduced are the day geckos, which are active during daylight hours, unlike many nocturnal species. The Gold Dust Day Gecko, Phelsuma laticauda, is a vibrant green gecko with distinctive gold speckles and red markings, originally from Madagascar. This species was intentionally, yet illegally, introduced to Oahu in 1974. Other day geckos include the Orange-spotted Day Gecko, Phelsuma guimbeaui, and the Giant Day Gecko, Phelsuma madagascariensis, both of which are established on Oahu.
How Geckos Arrived in Hawaii
The geographical isolation of the Hawaiian Islands historically limited the arrival of most terrestrial reptile species through natural means. Geckos primarily reached Hawaii as accidental stowaways on human vessels. The earliest species, such as the Mourning and Stump-toed Geckos, arrived with Polynesian voyagers over 1,500 years ago, hidden within their canoes or cargo. This ancient form of transport inadvertently introduced these adaptable reptiles to the islands.
Later introductions, particularly in the 20th century, occurred through modern shipping and cargo. The Common House Gecko, for instance, likely arrived during or after World War II, hitchhiking on cargo ships. Other species, like the Gold Dust Day Gecko, were introduced more recently, sometimes through deliberate, albeit illegal, releases.
Impact on Hawaii’s Ecosystem
The presence of introduced gecko populations in Hawaii has various ecological consequences, particularly for the islands’ unique native biodiversity. Geckos are primarily insectivores, consuming a wide range of invertebrates, including flies, mosquitoes, beetles, and spiders. While this can be beneficial in controlling household pests, their foraging habits extend to natural environments.
In natural forests, introduced geckos compete with native insectivorous birds and invertebrates for food resources. This competition can impact the populations of native insects, some of which are endangered, and reduce food availability for native predators.
Some gecko species, like the Common House Gecko, have also been observed displacing other gecko species, including the Mourning Gecko and Stump-toed Gecko, and even preying on smaller geckos. Geckos can also influence native plant pollination cycles. Certain day gecko species, such as the Gold Dust Day Gecko, consume nectar and fruit. While they can act as pollinators in some instances, there is concern that they may also damage the reproductive structures of native plants while feeding. The long-term effects of these interactions on Hawaii’s flora, which evolved without the presence of such reptiles, are a subject of ongoing study.