March 17, 2012
-- Many of Ireland's native species are now under threat as foreign species introduced to the Green Isle offer competition. A new study, published in the journal Biological Invasions, found that if the problem persists, many of the native will die out in at least 80 percent of their habitat. "The introduction of alien mammals to Ireland over the last 100 years has had major detrimental effects, threatening our indigenous habitats and species," said Ian Montgomery, a researcher from the School of Biological Sciences at Queen’s University who led the study. The domestic cat-sized pine martin belongs to the mustelid family, which also includes badgers, minks, otters, weasels and wolverines. Although the pine marten has plenty of animal predators, such as certain birds of prey, humans pose the biggest threat.
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The group Invasive Species Ireland tracks the impact non-native species are having on the northwestern European island. Grey squirrels are on the group's "Most Unwanted" list. Local red squirrels, such as this one, are threatened by the American grey squirrel, which Montgomery said "passes a deadly virus to native red squirrels."
The domestic cat-sized pine martin belongs to the mustelid family, which also includes badgers, minks, otters, weasels and wolverines. Although the pine marten has plenty of animal predators, such as certain birds of prey, humans pose the biggest threat. Habitat destruction, illegal poisonings, shootings and more have caused pine marten numbers to drop in recent years.
Ireland's largest wild mammal is the red deer. Thanks to reintroduction and conservation efforts, its populations are not suffering the same fate as Ireland's other native species.
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Hunting, habitat destruction, invasive species and other problems have plagued Ireland's native grey partridges. Thanks to the National Parks and Wildlife Service and organizations like the Irish Grey Partridge Conservation Trust, these birds are making a comeback. Recently, several of the partridges were released on a farm in north County Dublin, a place where the birds hadn't been seen in the wild in decades. Jimmy Deenihan, the Minister for the Department of Arts, Heritage and Gaeltacht, said that the bird had not been seen in parts of the county since the 1950's. "This (conservation) project clearly shows how farming practices in the 21st century can collaborate with nature conservation agencies to the betterment of our wildlife," he said.
The pygmy shrew is the only shrew native to Ireland. Montgomery and his colleagues found that in the recent past, this animal has completely vanished in parts of Ireland where two invasive species, the bank vole and the greater white toothed shrew, are found. Small mammals like the pygmy shrew occupy central positions in food webs, so major changes in species composition, which are already occurring, will have both top-down and bottom-up effects. These will affect bird and mammal predators as well as the invertebrates, seeds and seedlings that small rodents and insectivores feed on.
The viviparous lizard is the only terrestrial reptile native to Ireland. Although not currently classified as endangered, the lizard is under threat by humans mainly as a result of loss of habitat.
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The tiny wood mouse has suffered tremendously in recent years as a result of invasive species. Its numbers have decreased by greater than 50 percent in areas where the bank vole (an invasive species) is longest established. "Governments, both north and south of the border, are urged to work together to address the overall problem of invasive animals throughout Ireland," said Montgomery.
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