Some of the world’s most unique animals can be found on islands. Ecosystems and predator-prey relationships on islands are more closed-off than their mainland counterparts, paving the way for some distinct adaptations—think of enormous Komodo dragons, Varanus komodoensis, (indigenous to the Indonesian island of Komodo and surrounding islets) or tiny Key deer, Odocoileus virginianus clavium, (indigenous to the Florida Keys). But island life isn’t always easy and even the smallest ecosystem changes can put these animals at risk.
Here are two species that have adapted to the island lifestyle, but are now under threat due to human activity and invasive species.
Kākāpō
Evolving on the islands of Aotearoa (New Zealand) with few predators and plenty of space, these birds adapted to life on land in a big way. Kākāpōs (Strigops habroptilus) are the only flightless species of parrot in the world—and happen to be the heaviest, too.
Without predators, kākāpōs safely foraged on the ground and picked fruit from trees without a need for flight. But all that changed with human settlement. In the 13th century, the Māori introduced dogs and rats, which prey on kākāpōs, to the island. The threat was accelerated when Europeans arrived in the 19th century with the transplantation of more rats and also cats and mustelids, such as stoats and weasels. The newer settlers also removed much of the birds' habitat through deforestation, which was done to make land available for farming and grazing.
As of September 2024, there are about 250 individuals left—up from about 60 in in the late 1990s. In conjunction with Ngāi Tahu, a Māori iwi (tribe) who are the kākāpōs traditional protectors, government conservation began in 1995. Efforts centered on preserving the birds on the nation’s offshore islands where predators had been systematically removed. In September 2023, conservationists began returning kākāpōs to the mainland. The birds were taken to Sanctuary Mountain Maungatautari on the North Island.
Solenodons
Solenodons have been on islands of their own for a very long time, both genetically and geographically. Solenodons retain primitive mammal characteristics; DNA studies indicate they diverged from other mammals about 78 million years ago. Today, there are two remaining species, each indigenous to a large Caribbean island (Cuba, Atopogale cubana, and Hispaniola, Solenodon paradoxus).
Once a dominant predator on these islands, solenodons adapted an omnivorous diet and are one of the few venomous mammals in the world. Even their venomous bite, however, has not protected them from the introduction of other predators (mongoose, dogs (Canis familiaris), cats (Felis catus)), competing foragers (rats and mice), and human development. These forces have put solenodons at risk.
In its red list of threatened species, the International Union for Conservation designated the Cuban solenodon as endangered and the Hispaniolan solenodon as least concern. The Hispaniolan solenodon has been sighted in across the island in a relatively large range, 80,493 kilometers2 [31,079 miles2]. This is unlike the Cuban solenodon, which has been only spotted in a single location within a small area (3,280 kilometers2 [1,266 miles2]). Human industry (deforestation and mining) and invasive species brought by humans have lessened the habitats of both species. But only the Cuban solenodon’s population has dropped because of habitat loss.
