My fascination with earthworms began several years ago. I was doing research on insect biodiversity in remote parts of northern Saskatchewan for an organization called Troutreach. When my field partner and I happened upon an earthworm, this seemed an unremarkable discovery to me because, like most Canadians, I was used to seeing them in my yard. My better-informed colleague, however, knew this was an unusual place for an earthworm to be. That’s because earthworms were wiped out in most of what is now Canada and the northern United States during the last ice age. Earthworms migrate very slowly and never recolonized these regions after the icesheets retreated, leaving most Canadian forests naturally earthworm-free. The earthworms most Canadians are now used to finding in their gardens or scattered across the sidewalks after a summer rain are non-native European species that have been introduced over the last few hundred years since the arrival of European settlers.

While working in northern Saskatchewan, I started casually looking for earthworms in my spare time; turning over logs, noting where they were, and wondering how they got there. Beyond my own curiosity, this turned out to be an important question, and I wasn’t the only one trying to answer it. As I learned more about earthworms, I kept reading about one of Canada’s foremost earthworm researchers, Erin Cameron, who is a professor at St. Mary’s University in Halifax. Ultimately, I was fortunate to end up pursuing my PhD in Cameron’s lab.

In 2021, we designed a study to determine if earthworms are also spreading through lakes and rivers. This is difficult to study in nature, but we found a great place to answer this question. Lac La Ronge is a large lake in northern Saskatchewan with over 1,300 islands. While working in the area, we came to realize that many of these islands have non-native earthworms on them. By understanding the distributions of earthworm populations on these islands in relation to human activity and island geography we can determine how they are spreading. This project is ongoing, but it seems that at least one species of non-native earthworm regularly disperses though water in northern Canada.

To better understand the factors affecting the spread of earthworms in Canada, we are also determining their occurrence at the northern margins of their distribution. Distributional data on earthworms is very limited in Canada and records of earthworms in the Canadian territories are especially few and far between. It is unclear if this is because earthworms are in fact rare at these high latitudes, or because almost no one is looking for them. So, we set out to do the first structured and quantitative survey of earthworms in the Yukon.

The concept is simple, but collecting the data is tough. Each of the last three summers, I’ve spent about three months conducting fieldwork in remote forests, working long days rain or shine, and often living in a tent. I work with a team of research assistants to systematically sample northern forests to see if earthworms are there, and if so, how many, and what species. I then relate these data to factors that might explain why the earthworms are (or are not) there, and will use statistical models to make predictions about their distribution across the landscape.