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  • Discovering Kwilákm
    • About
    • Get Involved
  • Changing Climate
    • Hotter Ocean Temperatures
    • Changing Ocean Chemistry
    • Rising Sea Levels and Intensifying Winter Storms
    • When Seashore Temperatures Spike – Killer Heat Dome 2021
  • Terminal Creek
    • Where does Terminal Creek’s Water Come From?
    • Signal Crayfish
    • Terminal Creek Fish Hatchery
  • The Lagoon
    • The Tidal Inlet that became the Lagoon
    • Aquatic Plants
    • Chum Salmon
    • The Beaver
    • Canada Geese
    • Three-Spined Stickleback
  • Shores
    • Nearshore Forests
    • Beaches
    • The Terminal Creek Sand Flats
    • The Curious Clay Beds of Kwilákm
    • Blue Mussels
    • Clams
    • Purple Stars
    • Oysters in Kwilákm
  • Shallows
    • Eelgrass
    • Young Chum Salmon
    • Winter Bay Birds
    • Year-Round Bay Birds
  • Deeper Waters
    • Plankton
    • Northern Anchovy
    • Harbour Seal
    • Octopus

Photo: Will Husby

The Lagoon

The Beaver

(Castor canadensis)

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  • Beavers on Bowen – A Personal History
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Discover Kwilakm » Story » The Lagoon » The Beaver
Beaver at the lagoon
Photo: Bob Turner

Beavers on Bowen — A Personal History

By Alan Whitehead

There were no beavers on Bowen Island/Nex̱wlélex̱m when my young family and I moved here in the early spring of 1988. Beavers first appeared in the early 1990s in the Lagoon and soon moved upstream all the way to Killarney Lake. Long-time residents told me there had been muskrats, which had been trapped out in the first half of the 20th century, but told no similar stories of beaver. Now beavers, their dams, lodges, and cut vegetation can be found in many places, mostly but not only in the Killarney-Terminal watershed.

Map of Terminal Creek watershed and beaver sightings
Recorded distribution of Beavers on Bowen Island. Map: Alan Whitehead/Will Husby

Were beavers present on Bowen Island before the early 1990s? Where did they come from? How did they get here? Are they here to stay? My hypothetical answers below are based on the stories I’ve heard, reviews of beaver ecology, and personal observations on and off Bowen over the years.

Kwilákm is the beavers’ main doorway to the island. We know from personal observation that their arrival in the 1990s was on the east side of Bowen, via Kwilákm and the Lagoon. It is likely that they came from the Fraser Valley lowlands, where beaver populations have been increasing over the past century as a result of the decline in trapping, construction of drainage canals, and other changing land uses.

Beavers are strong swimmers. Although they live in fresh and brackish water, they are known to cross significant spans of saltwater; this happens particularly when the young adults are dispersing away from their birth habitat after their second year. Beavers would have no trouble navigating the waters between the mouth of the Fraser River and Bowen Island and beyond.

Presumably, they are attracted to freshwaters that smell of marsh vegetation and organic sediment. I can picture a beaver swimming out of the Fraser River’s North Arm into the mouth of Howe Sound, passing by the mouths of smaller streams that, though freshwater, do not smell of wetland and lake and are not explored. Likely, the first attractive outflow the beaver would come to would be the freshwater plume from the Lagoon, tasting and smelling like a possible future home.

Initially, based on the old-timers’ accounts, I thought that beavers had not been present on Bowen until the last decade of the 20th century. After all, mature coniferous forest in a mountainous setting wrinkled with narrow- bottomed V-shaped valleys and few permanent streams, does not normally provide ideal beaver habitat.

Once I started to explore the island, however, I discovered what appeared to be the remains of three ancient beaver dams at the marsh known as Mud Lake, above Killarney Lake on the west side of Collins Mountain. The uppermost dam retains water in Mud Lake itself; the next two create the ponds at the headwaters of upper Honeymoon Creek that flows into Honeymoon Lake.

Trees on Beaver Dam
Growing along the crest of each dam is a line of several large red cedar trees. Their large diameter, up to about 18 inches, suggests that the dams have been there since well before the early 1990s. Photo: Alan Whitehead

Mud Lake is a saddle wetland perched on the divide between two small watersheds; it drains in two directions: normally to Honeymoon Creek and, during highest water levels, to upper Killarney Creek and the lake.

Currently, descendants of the latest wave of immigrant beavers have again taken up residence at Mud Lake, where a lodge and beaver-cut trees can also be seen. As before, it is likely that the dispersing beavers arrived from Killarney Lake, following the scent of marshy water. Other ancient beaver dams, or their remains, may have been present elsewhere on Bowen. However, all the island’s main lakes, which are the obvious places to look for beaver history, have been dammed for human water supply; the higher water levels and natural decomposition would have erased any traces of dams or lodges or beaver-cut stumps.

Wetland created by Beaver dams
A large wetland created by beavers along Killarney Creek in Crippen Park. Note the dead trees. Ponded waters killed the forest, allowing sun-loving marsh plants to thrive here. Photo: Will Husby

Are the beavers now here to stay? Yes, but not in large numbers and only in the best habitats, and only where they don’t conflict with humans. Interestingly, where water and topography allow, beaver activity can actually create just the environment that favours the growth of wetland and deciduous riparian vegetation they need to thrive.

But those conditions aren’t widespread. Judging from the large girth of some of the cedars that have been gnawed as a source of bark for food, life may not be easy for the young beavers that, during their dispersal, try out more remote locations. In these areas, the preferred forage plants are scarce and the streams and wetlands tend to go dry during the late summer and early fall, leaving beaver dams useless, their dens exposed.

Beaver lodge covered in snow.
Snow on one of Killarney Lake’s beaver lodges in January 2021. Other lodges with underwater entrances are excavated into the lake bank. Photo: Alan Whitehead
Beaver bank burrow diagram
Beaver bank burrow

I’ve seen beaver-gnawed trees in other, smaller watersheds on the east and west sides of Bowen, but all these sites have been abandoned, likely because the stream or wetland went dry during the summer.

In the prime habitats, however, such as Crippen Regional Park, the municipal park at Grafton Lake, Headwaters Park, and possibly other existing and future protected areas that have suitable conditions and minimal human interference, beavers will likely endure. All they will need is an abundance of year-round food and watery shelter habitat, plus a connection to Howe Sound for dispersal and recruitment of mates to maintain genetic diversity. 

A beaver-cut holly tree at Grafton Lake.
A beaver-cut holly tree at Grafton Lake. Beavers feed on the inner bark, green twigs and shoots. Photo: Alan Whitehead

Please feel free to help us fill the gaps in Bowen Island’s natural history. To contribute any additional information that you may have on the history of beavers and their present distribution on Bowen Island, contact us at BowenNatureClub@gmail.com.

Alan Whitehead is a long-time resident of Bowen Island, a professional biologist, and the Volunteer Warden of the Ecological Reserve on Mt. Apodaca.

More About The Lagoon

  • The Lagoon
  • The Tidal Inlet that became the Lagoon
  • Aquatic Plants
  • Chum Salmon
  • The Beaver
  • Canada Geese
  • Three-Spined Stickleback


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