• 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 (indigenous to the Indonesian island of Komodo and surrounding islets) or tiny Key deer (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.


    Evolving on the islands of New Zealand with few predators and plenty of space, these birds adapted to life on land in a big way. Kakapos are the only flightless species of parrot in the world—and happen to be the heaviest, too.

    Without predators, kakapos safely foraged on the ground and picked fruit from trees without a need for flight. But all that changed with human settlement and introduced species such as cats, rats, and weasels. Today there are fewer than 160 kakapos left.


    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 and Hispaniola).

    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, cats), competing foragers (rats and mice), and human development. These forces have put solenodons at risk. Both the Cuban solenodon and the Hispaniolan solenodon are currently listed as endangered species

    1. Solenodons and kakapos have adapted to make the most of their island environments. Can you think of other species that have done the same?

      Answers will vary!

      • Marine iguanas, native to the tropical Galapagos Islands, are lizards with primarily terrestrial relatives. Their impressive swimming capabilities help them to access and eat underwater seaweed.
      • Galapagos finches, nicknamed “Darwin’s finches” include about 15 species of birds, each with a distinguishable beak. Each beak is ideally adapted to a specific food source—big and tough for cracking nuts, long and thin for extracting nectar.
      • Island foxes look like their mainland relatives, but are closer to the size of your typical house cat. Scientists think factors such as overcrowding, a lack of predators, and resource limits helped make the foxes’ tiny size a beneficial mutation for life on the Channel Islands, off the California coast.
    2. What are the major threats to island ecosystems?

      Answers will vary!

      There is a finite amount of space on an island and human development puts these unique, isolated ecosystems at risk. Agriculture, resource extraction, and tourism create pollution and remove original habitats. Even ecotourism models with the best intentions contribute to the ecological strain human activity places on island ecosystems. 

    3. There were only 18 kakapos left in 1970, but scientists were able to manage the remaining population, which grew to 123 in 2014. What do you think drove the kakapo recovery?

      Kakapos greatly benefitted from environmentally conscious citizens and volunteers, who spread the word about this endangered species and encouraged people to donate to recovery programs. There are lots of endangered species out there and individual actions, like donations and generating awareness, can make a difference. 

  • Term Part of Speech Definition Encyclopedic Entry
    adaptation Noun

    a modification of an organism or its parts that makes it more fit for existence. An adaptation is passed from generation to generation.

    Encyclopedic Entry: adaptation
    characteristic Adjective

    particular feature of an organism.

    diet Noun

    foods eaten by a specific group of people or other organisms.

    Encyclopedic Entry: diet
    distinct Adjective

    unique or identifiable.

    diverge Verb

    to differ or branch in two or more different directions.

    DNA Noun

    (deoxyribonucleic acid) molecule in every living organism that contains specific genetic information on that organism.

    dominant Adjective

    main or most important.

    ecosystem Noun

    community and interactions of living and nonliving things in an area.

    Encyclopedic Entry: ecosystem
    endangered species Noun

    organism threatened with extinction.

    Encyclopedic Entry: endangered species
    enormous Adjective

    very large.

    forage Verb

    to search for food or other needs.

    genetic Adjective

    having to do with genes, inherited characteristics or heredity.

    geographic Adjective

    having to do with places and the relationships between people and their environments.

    indigenous Adjective

    characteristic to or of a specific place.

    Encyclopedic Entry: indigenous
    introduced species Noun

    a species that does not naturally occur in an area. Also called alien, exotic, or non-native species.

    invasive species Noun

    type of plant or animal that is not indigenous to a particular area and causes economic or environmental harm.

    Encyclopedic Entry: invasive species
    island Noun

    body of land surrounded by water.

    Encyclopedic Entry: island
    islet Noun

    a very small island.

    mammal Noun

    animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.

    omnivore Noun

    organism that eats a variety of organisms, including plants, animals, and fungi.

    Encyclopedic Entry: omnivore
    predator Noun

    animal that hunts other animals for food.

    prey Noun

    animal that is hunted and eaten by other animals.

    primitive Adjective

    simple or crude.

    unique Adjective

    one of a kind.

    venomous Adjective

    having to do with venom or organisms that secrete venom.