We are aware of how the islands have been invaded by invasive species such as cats, rats, snakes and other animals who have arrived there innocently or deliberately by boat. These animals then led to the extinction or eradication of native animals.
Island Conservation based in Santa Cruz, California, since their founding in 1994, has successfully restored 65 islands around the world, benefiting over 1,200 populations of over 500 species and subspecies. They have a handful of offices around the world that have already done so much in a short amount of time.
75% of the extinctions of mammals, birds, reptiles and amphibians have occurred on islands, most of which are birds. Invasive species are implicated in 86% of all these recorded extinctions. Islands comprise 5% of the land mass of the earth, with over 450,000 islands in the world.
Biologists have documented a 5,000% increase in the recruitment of native trees on Palmyra Atoll after mouse eradication, while restoring the terrestrial ecosystem allows for more resilient oceans to be built within the confines of marine protected areas. The calves of the Pinzon giant tortoise survive for the first time in over a century and a half after the rat’s eradication.
The most significant eradication project of 2021 on Tristan de Cunha’s Gough Island involved invasive house rats responsible for the loss of more than two million seabird chicks and eggs each year. Over 20 species of seabirds nest there and is home to two endemic land bird species, the Tristan Albatross and the Atlantic Yellow-Nosed Albatross, which took two months to complete due to weather conditions.
In 2020, the Robinson Crusoe Island community (400 miles off the coast of Chile) removed the world’s first invasive coati to save the berta piedirosa, one of only three nesting islands in the world. Shearwaters were nearly down for the final tally with invasive rabbits and goats removing vegetation, while mice, rats, and feral cats broke into nests and attacked adult birds.
It took the island of Lehua in Hawaii a decade to remove invasive rats by Earth Day 2021 for threatened and endangered breeding Hawaiian seabirds. The rabbits were removed from the State Seabird Sanctuary in 2006, but the mice were more resilient. The wedge-tailed Berta, the red-footed Gannet and 14 native plants have been restored. Seabird guano increases the vigor, diversity, health and size of manta rays, fish and corals, as a symbiotic relationship.
Hawadax Island (Island of Mice) in the Aleutian archipelago had a double cleanup with rats in 2008, an ecosystem recovering five years later and a fully recovered system in 11 years. With the mice gone, the breeding seabirds are back and are once again dining on their coastal invertebrates, allowing the algae community to recover and rebound.
Invasive house mice were removed from Allen Cay, Bahamas in 2013, which allows for new life at Allen Cay Rock Iguana, Bahama Yellowthroat, and Audubon’s Shearwater.
The importance of the islands to the reproductive populations of birds and other animals is necessary to increase the depleted life over the past half century.
Deb Hirt is a wild bird rehabilitator and professional photographer based in Stillwater.