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What Can We Learn From 77-Year-Old Mouse Fur?

Following in the footsteps of a legendary BC naturalist.
December 15, 2016

In the summer of 1939, legendary British Columbian naturalist Ian McTaggart-Cowan boarded the MV Seabird with his wife and two close colleagues, and set off from Namu, a small coastal community about 450 kilometers northwest of Vancouver. The crew sailed the Inside Passage through the remote BC Central Coast, and conducted the first systematic surveys to describe the diversity of marine birds and small mammals. Now, 80 years later, a team of scientists is retracing their steps.

Ian McTaggart Cowan notes from 1939 British Columbia biodiversity expedition at Royal BC Museum archives
Correspondence by Ian McTaggart-Cowan from his 1939 expedition to the BC Central Coast. Notes were photographed by Nancy Shackelford with permission at the Royal BC Museum Archives under catalogue number GR-0111.3.2

As part of the collaborative 100 Islands Project, scientists from the Hakai Institute, University of Victoria, and Simon Fraser University are aiming to catalog the biodiversity on the islands—the plants, invertebrates, mammals, and birds. Like the 1939 expedition, present-day researchers work long hours in pouring rain or the occasional glorious sunshine, observing the ecology of creatures living on these isolated islands. Their work delves deep into our fundamental understanding of what drives ecological patterns on islands.

In the past, ecology has viewed the ocean surrounding islands as an empty space waiting to be crossed by dispersing species. The reality is that the ocean is far from empty. It is not only a medium through which species can disperse, but also an abundant nutrient source. Seaweeds wash up on beaches. Minks scoop up shellfish. Nearshore plants are fertilized by guano from marine birds, also known as avian poop. Despite the strong ties between ocean and islands, how the nutrients from the ocean influence and interact with species on coastal islands is relatively unknown.

That’s where the 100 Islands Project comes in. In one study, University of Victoria master’s student Katie Davidson is using chemical analysis to trace how nutrients that originated in the oceans are transferred to mice that live along the shoreline. By taking small hair samples from the mice, Davidson is testing how reliant each animal is on ocean-based food sources, such as the tiny creatures that thrive on washed-up kelp. And thanks to the fastidious notes and collections of McTaggart-Cowan, she can also test whether the marine-terrestrial relationship has shifted over the last 80 years.

Working with Dr. Gavin Hanke, the curator of vertebrate zoology at the Royal BC Museum, Davidson is taking hair samples from McTaggart-Cowan’s original mammal collections. From chemical differences between the hair of modern-day mice and mice from the 1940s, scientists may elucidate any consequences of the dramatic changes that have occurred in global climate conditions, ocean temperatures, and marine communities over that time.

Keen's mouse Katie Davidson
A Keen’s mouse sprints back into the bushes after leaving distinct footprints in the pipe set out by University of Victoria and Hakai Institute scientists to track the biodiversity of small mammals on BC Central Coast islands. Photo by Katie Davidson

Chris Darimont, who leads the mammal team on the 100 Islands Project, remembers sharing tea and stories with McTaggart-Cowan before he passed away in 2010.

“He could instantly bring us back to Goose Archipelago [on the BC Central Coast] in the 1940s, remembering exactly where the heron rookery was, or what watersheds on Hunter Island had evidence of wolf dens,” says Darimont, a Hakai-Raincoast professor at the University of Victoria.

Experiences like these, coupled with the tireless efforts of museums to maintain historical collections and the millennia of observations by the area’s Heiltsuk and Wuikinuxv Nations, tie together generations of coastal research. By comparing baselines established by early expeditions, present-day scientists can understand long-term coastal patterns, even as the world continues to change around us.

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