Climate change may be a huge threat to many animals around the world but do you know what the second most dangerous threat is? Invasive species is a close second to habitat loss. Not what you had expected? If anywhere is the poster child for the destructive power of invasive species, Australia has to be it (not saying that other nations are not faced with equally devastating species). A number of species arrived with the European colonization and many continue to impact the biodiversity of this island nation. From wild horses to feral cats to rabbits to cane toads, each has done great damage and sometimes the solution becomes a bigger problem. (We are talking about you Mr. Cane Toad.) Management of these invaders is a full-time job and costs the Australian government millions of dollars annually.

Let us start with some background on this topic before I introduce you to some of our worst problems here in Canada. An invasive species is a species that is not native to an area and has the tendency to spread. They cause damage to the environment, economy, and animal (humans included) health. There is some controversy over the exact definition but the following are a good example of the characteristics of invasive: rapid growth and reproduction, high dispersal ability, the ability to change their growth form to suit the environment (also known as, phenotype plasticity), the tolerance of a wide variety of environments, the ability to live off a range of different food types, and the association with humans. Many, if not the majority, of these invasive species are first introduced by humans, either on purpose such as exotic garden plants that take off like phragmites or as stowaways on sailing vessels, quite literally like the Norwegian rat (that is the fancy name for your run-of-the-mill, rat). Species are brought to new areas when these areas are settled by people. 

In Canada, we have so many of these invading species that it would take a lot more room that this blog to list them all but here are a few of the most destructive ones:

Emerald Ash Borer – Anyone who camps in eastern Canada knows this name because it is suspected that the transfer of firewood from one area to another is a main vehicle of spread. This bright green beetle from eastern Asia has been decimating ash forests throughout Manitoba, Ontario, Quebec, New Brunswick, and Nova Scotia after making its way from the US where it is now found in at least 35 states. It probably came in wood packing material from Asia to North America in the early 1990s but it wasn’t until around 2002 that it was detected. The females lay their eggs under the bark of the ash trees that will kill the tree within 4 years of infestation. With few natural predators, hundreds of millions of dollars may end up being spent to try and stop their spread. Here is Ottawa, we saw hundreds of ash trees removed a couple of years ago throughout the city to try and halt these beasties’ progression.

Phragmites – These tall ornamental grasses were first brought to Canada from Eurasia decades ago and having been clogging up ditches and waterways ever since their arrival. It is a very aggressive plant that wins the battle for nutrients and water against native grasses. It is so prevalent and looks very similar to some of our grasses that most people do not even realize that they are not native. It releases toxins into the soil surrounding it to poison other plants, can reproduce by both seed and rhizomes (a long root system) that it is extremely hard to completely eradicate it. 

Zebra Mussels – This is another invader that has been spread by movement of men in boats. This is a freshwater mussel that originally hailed from Russia and Ukraine and found its way to our Great Lakes (as well as elsewhere in North America, the UK, Italy Spain, and Sweden) via ship and boat hulls. They first appeared here in 1988 and have been clogging up waterways and treatment plants ever since. Anyone who has swum in zebra mussel areas remember the feet slicing ability of their shells and people with boats are always told to clean the hulls before changing bodies of water. 

Eastern Grey Squirrel – Who knew that this cute fluffy-tailed rodent is one of the top 100 invasive species in the world? These are the grey and black squirrels that you see throughout eastern Canada but they are not supposed to be out west. People may love them but they have displaced many native species throughout Canada and the world. They will steal birds’ nests and eat eggs and hatchlings, compete for resources with native voles and mice, and spread disease (paropoxvirus). They have taken over huge areas in British Columbia including Stanley Park in Vancouver where they were introduced in 1909. They have become such a nuisance that homeowners are permitted to shoot or humanely euthanize them.

This is just a small selection of invasive species; there are so many more that you could research including fish, fungi, and amphibians. They pose a threat to our native wildlife and fauna and are a costly problem to solve. Awareness is the start of the solution. Know what these species are and how they are spread and maybe we can stem the invasion. Pun completely intended.

–Janice Willson

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