America, continental Europe and Asia have been blamed for much of Ireland’s invasive species. These alien plants and animals have adapted so well to our climate that they compete aggressively with native wildlife, often leading to a decline in their numbers. Ireland’s most unwanted and famous invaders include grey squirrels, giant rhubarb and more recently harlequin ladybirds. After giving my evil stare to yet another grey squirrel, I wondered are there any Irish wildlife invading other countries in the same way? Time to conduct my own mini-experiment!
Since our enemy, the grey squirrel, is from North America, I turned to the United States Department of Agriculture. After trailing through lists of invasive aquatic, plant and animal species, I found twenty species which had specifically European or Mediterranean origin. By checking the National Biodiversity Centre’s database, I discovered eight of these were found in Ireland.
Though harmless in Ireland, these plants crowd out native species in North America causing similar problems as giant rhubarb. The shore crabs are similar to harlequin ladybirds as they prey on native crustaceans and the starling like the grey squirrel competes with native species.
The introduction of these species has occurred in a variety of ways including intentional (planting ornamental plants) and accidental (shipping, contaminated seeds). I was very quick to blame our European neighbours for their contaminated seeds and shipping fleets until I noticed the introduction dates. Two of these species, the common reed and shore crab were first introduced in the US by accidental means through shipping in the 1800s. Since these species are very common in Ireland and we had mass emigration to the U.S. during the 1800s, we could have been responsible for transporting some innocent hitchhikers!
The award for most bizarre intentional introduction has to be given to the Starling. The American Acclimatization Society introduced these birds as part of a project to introduce every bird mentioned in Shakespeare’s works. They are referenced in Shakespeare’s history play, Henry IV, Part 1 “Nay, I’ll have a starling shall be taught to speak nothing but ‘Mortimer,’”. In 1890 they released about one hundred of these European birds in Central Park. Today more than 200 million starlings are present in North America and they are considered invasive as they compete with native birds and damage crops! Ironically starlings have conservation status in Ireland due to moderate recent declines in large parts of its European population.
My quick experiment has shown that Irish plants and animals aren’t as innocent as we perceive them to be. Like the Irish people who emigrated abroad, these eight plants and animals found better opportunities in Northern America and flourished… a bit too much!
Shore Crab Photo: http://www.eos.unh.edu