Invasive Species: A Tale of Two Spellings

By Kelly Vowels

What is in a name? I always find it interesting that words in the English language can be spelled differently but mean the same thing depending on where you are in the world. An interesting example is raccoon. Raccoon can be spelled with two Cs and one C, and it means the same cute species, the common raccoon (Procyon lotor). The spelling with two Cs is much more common, especially in the raccoon natural range in North America. The spelling of one C is used more in Europe, where they are not native. Another example is gray versus grey, which is used differently when discussing squirrels. In North America, they are gray squirrels, while in Great Britain they are grey squirrels. They are both Sciurus carolinensis. The other interesting thing about gray squirrels and the common raccoon is they are considered invasive in Europe. A lot of times when people are discussing invasive species, they think about the species that are invasive in their areas and don’t realize that a common native species in one place can be very invasive in another. An invasive species is a species that has been introduced to an area where there are no natural checks on its spread, and it can displace native species.

The common raccoon in North America is a mammal that everyone knows and in its natural range, it has predators and diseases that keep the populations from getting out of control. Also, their prey has evolved with them and have natural defensives to protect themselves. In Europe, they were introduced mainly for the fur trade in the 20th century and have spread to more than 20 countries. They have caused problems in these countries, preying on the natural wildlife and spreading diseases that native wildlife in Europe have no defenses against. An example of this is the black stork (Ciconis nigra), an endangered bird. In areas where storks and raccoons overlap, the raccoon has negatively impacted the stork. Raccoons will climb 25 meters into stork’s nest to eat eggs and chicks. Black storks are already affected by habitat destruction and are extremely sensitive to disturbance. The threat of raccoons is an additional threat to their continued existence.

Gray squirrels were introduced to Great Britain in the 1890s and have spread across the island. They have caused extensive damage. They were also introduced to Ireland when over a hundred years ago 12 gray squirrels were gifted as a wedding present and escaped. They are now found throughout Ireland and have dramatically impacted the native red squirrel (Sciurus vulgaris) populations. The gray squirrel will push the red squirrel out of areas by outcompeting them for food and space, and the gray squirrel will spread squirrel pox virus to the red squirrel. The gray squirrel is immune to pox, but the red squirrel is very susceptible to the disease. The red squirrel population in Ireland has declined by more than 20% since the introduction of the gray squirrel.

So I have found that it is important to understand that any species outside its normal range can become invasive. This includes not only animals but also plant species. Our goal here at Bernheim is to continue to monitor and protect the natural world from these species, and to be responsible stewards of the land.

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