I had a conversation recently with my friend the birder. He pointed out various bird species that happened to fly within line-of-site of our gathering, while noting which ones were native species and which ones were transplants. That led to discussions of various invasive animals introduced into North America either by accident or by design, and the havoc those alien encounters sometimes introduce.
I’ve talked about Zebra and Quagga Mussels in the Great Lakes before as well as Asian Carp in the Mississippi watershed. Those are good examples. Closer to home, we’ve had to deal with Snakehead fish and vicious Tiger Mosquitoes. Let’s not forget those ghastly primates, those homo sapiens either. They’ve been causing trouble everywhere.
We tend to think of ourselves in North America as the recipients of every other continents’ castaway pests. However, it’s not a simply one-way street. Plenty of cute and cuddly North American animals we see every day become nuisances elsewhere. Sometimes they even push native species to the brink of extinction.
Take for instance the prime example I used during my conversation:
Eastern Gray Squirrel
People spell it a little differently in the United Kingdom: grey squirrel (i.e., gray vs. grey). Nonetheless, these creatures pose a major problem. The grey squirrel competes relentlessly with the native red squirrel. The Global Invasive Species Database explains that “Eastern gray squirrels were introduced to Italy and England from the U.S., to Scotland from Canada and to South Africa and Ireland from England.”
In the UK, grey squirrels have pushed native red squirrels northward. They cannot live within overlapping ranges because grey squirrels are larger, more competitive and voracious eaters. Grey Squirrels also have immunity to diseases they carry and subsequently spread to Red Squirrels, with harmful results.
Pushing Back
Groups in the UK such as the Red Squirrel Trust Wales and Cornwall Red Squirrel Project want to push the clock backwards by reintroduce red squirrels into their previously-native habitat, for example:
“The aim of the project is to re-introduce Britain’s native red squirrel into Cornwall. Red squirrels (Sciurus vulgaris) were common in England until the grey squirrel (Sciurus carolinensis) was first introduced to the UK from America as an ornamental species in 1876 and to Exeter in 1915. The spread of the grey squirrel was rapid, and in 36 years the species had reached Cornwall. The last of our native red squirrels was seen in Cornwall in 1984.”
Taken Aback
It’s hard to imagine the damage caused by these common mainstays of the eastern North American outdoors when exported elsewhere. I note one more quote — completely irrelevant by the way — from the Invasive Species Database. My relatives in Mississippi will enjoy this. “Grey squirrels (Sciurus carolinensis) are harvested for food in Mississippi (USA).”
For the record, my family does not eat squirrels. Also I should note that squirrel hunting takes place in many different places, not just Mississippi (case in point). I don’t understand why the database singled-out Mississippi.
If we’re talking about animals more-or-less commonly eaten, perhaps we should also note:
Canada Goose
Wikipedia has a nice map of the Canada Goose range, including it’s non-native habitat. It didn’t shock me to learn of their introduction to Europe. However they’ve surged in population in recent years. The Guardian focused attention on an emerging problem in France.
“There are certainly so many of them in France that they are beginning to pose a threat to wetland biodiversity. The Canada goose is the largest goose found in Europe. It was introduced to Britain in the 17th century, then adopted as a game bird on the continent during the last century. In the wild they live 10 to 25 years and are prolific breeders. They are now resident in western Europe and, for reasons that remain obscure, their numbers have started increasing very fast. There were only several hundred Canada geese in France at the end of the 1990s. Now there are more than 5,000 spread over at least 58 départements, with half in the Paris area.”
Canada Geese are also an issue on the other side of the world in New Zealand. NZ Birds traces their origin to “a gift from US President Theodore Roosevelt” in the early 20th Century. Unfortunately, “there are now so many of them they are sometimes regarded as a pest.” Gee, thanks Teddy. He probably deserves to lose every race at Nationals baseball games simply because of that.
Other creatures also got a one-way ticket from North America for the benefit of sportsmen.
Largemouth Bass
The Largemouth Bass serves as a mainstay of anglers particularly in the southeastern United States. They are quite common there and considered a great sports fish. So fishermen naturally stocked freshwater bodies around the world with them. Unfortunately Largemouth Bass are also extremely aggressive and hungry. They can destroy local native fish populations without even trying.
The Global Invasive Species Database includes Largemouth Bass too, and it notes:
“Largemouth bass are highly adaptable fish, able to thrive in virtually every warm-water habitat, from small creeks to large rivers to huge reservoirs. About the only thing that limits them is cold annual water temperatures… Known introduced range: UK, Europe, Russia, Middle East, North Africa, Continental US, Caribbean territories, South America, Asia, Southeast Asia, Hawai‘i, Mauritius, Madagascar, Fiji, Guam, New Caledonia and the US Virgin Islands.”
And the one I didn’t see coming:
Beaver
Beavers? Really? We even have beavers in an urban area boxed in between an Interstate Highway and office towers near my home in Virginia (satellite view). Where could beavers cause a problem?
Trappers released beavers in Tierra del Fuego in a failed attempt to create a fur industry in 1946. Now, a little more than half a century later, the governments of Chile and Argentina are working desperately to stop their spread. Beavers cause extensive damage to the local ecosystem, leaving a swatch of denuded forests and flooded fields in a destructive path pointed towards the north. This is all explained in an article in Nature, The Beavers Must Die. That’s the plan. They hope to eradicate the population permanently and with extreme prejudice.
I’m sure there are plenty of other examples. They are difficult to find because most of the information I could uncover related to invasive species coming into North America rather than moving the other way. Let me know if you have other favorites I haven’t mentioned.
Leave a Reply