Photo: Will Husby
The Lagoon
The Beaver
(Castor canadensis)
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.
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.
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.
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.
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.
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.