Threats
Feral GoatsFeral goats were brought to the islands as a source of food and have greatly endangered endemic plant species by excessive feeding and trampling on bare soil, increasing soil erosion. Specifically, on Nakodojima Island and the Mukojima Island Group, feral goats have eaten many of the plants and have increased exposed bare soil, causing greater soil runoff endangering coral reefs and other marine ecosystems.
CatsCats were brought to the islands as pets and as rat control, but over the years have become feral. The introduction of cats is one of the leading causes of the extinction of endemic bird species on the islands. Cats often prey on the endemic Bonin honeyeater (Apalopteron familiare hahasima) and brown bobby (Sula leucogaster). Feral cats are often mostly found on Chichijima, Hahajima and Ototojima Islands.
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Black RatsBlack rats were also introduced through ships and have radically impacted the vegetation through feeding on seeds and fruit. They have also threatened many species by preying on them, such as the nests of Bulwer’s petrel (Bulweria bulweri), the wedge-tailed shearwater, and endemic land snails.
Feral PigsFeral pigs and nonnative bullfrogs were brought as sources of food but have greatly threatened the five endemic dragonfly species. The bullfrogs feed on dragonfly nymphs while feral pigs damage dragonfly habitats by digging up the soil. The dragonfly species have disappeared from Chichijima and Hahajima Islands but are still present on Ototojima Island.
PlantsIn the early 1980s, a large typhoon hit the Ogasawara Islands in 1983 destroying most of the forest and allowing an introduced species, Bishofia javanica, to invade the natural forests and crowd out native trees. The Akagi trees, Bishofia javanica, were introduced before WWII to be used as firewood for sugarcane production and has problematically invaded native trees.
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