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  • Writer's pictureSoren Miles Fesel

The Invasive Species that Wreak Havoc in Hawaii

Invasive species are a pervasive problem in Hawaii. Countless plants, animals, and insects introduced in the last few centuries have wreaked havoc on native species, changed Hawaii’s ecosystems, and even caused issues for human residents. (Note: the two upper photos in this article have been provided by Skye Moore).

Below are a few of the most common and destructive animals found on the Hawaiian Islands.

#1: Mongoose

Photo credit: Skye Moore

The Mongoose (scientific name Herpestes javanicus) is a small, long rodent. Its physical appearance is similar to a weasel. This species thrives on several of the main Hawaiian islands.

Mongooses are omnivores and eat a wide array of potential foods such as plants, insects, birds, and even small mammals.

This species was initially introduced to the islands in 1883 by private sugar plantation owners in an attempt to get rid of the rat population damaging sugarcane yields.

This plan ended up backfiring because the Mongooses were mostly active during the day, and rats were mostly active during the night, preventing Mongooses from effectively hunting and killing the rats.

Over the last one-hundred-forty years of the Mongoose’s existence in Hawaii, it has harmed many native species.

Since the Mongoose constantly hunts birds in particular, many native Hawaiian birds like the Hawaiian crow (‘alalā), petrels (ʻuʻau), and Hawaiian goose (nēnē) have been targeted, according to the Hawaii Invasive Species Council.

#2: Goat

Photo credit: Sky Moore

The Goat (scientific name Capra hircus) is a domesticated member of the Caprinae sub-family. It has horns, and four legs, and tends to live in grassy, open areas across the Hawaiian islands.

They can frequently be found living and eating along highways and paths. As indicated by their habitat in Hawaii, they tend to eat grass, shrubbery, and other low-lying vegetation.

Goats were originally introduced to the island of Hawaii in 1778 by Captain James Cook as a gift to the Hawaiians. Eventually, the goats rapidly multiplied and became an issue on the islands.

Due to their insatiable hunger for grass and low-lying vegetation, goats have damaged many native shrubs and plants. Goats also present a danger to drivers, as they can easily be run over.

Fortunately, there have been some successful goat reduction programs according to Big Island Now. Roughly fifty years ago, there were an estimated 15,000 goats living in Volcanoes National Park. Now, because of proper fencing and goat hunting, that number is down to about one hundred active goats in the park.

#3: Coqui Frog

Photo credit: PBS

The Coqui frog (scientific name Eleutherodactylus coqui) is an invasive amphibian that thrives in damp environments. This small frog is mostly found in rainforests or other areas with high humidity and rainfall. They are usually noted for their incessant mating calls at night.

Coqui frogs were initially accidentally introduced in the 1980s. Plants imported from Puerto Rico contained some of the frogs, and they have remained very prevalent throughout the Hawaiian islands because of a lack of natural predators.

They currently live on several, but not all, main Hawaiian islands (they are not present on Kauai, Molokai, and Lanai).

Coqui frogs do a surprising amount of harm according to the Hawaii Invasive Species Council. By devouring many insects in forests and densely wooded areas, they disrupt the ecosystem by preventing bug pollination of various plants and preventing native species from consuming the insects for themselves.

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