Mountains for Marmots: The Return of the Vancouver Island Marmot
Figure 1. A pair of adult Vancouver Island marmots display common vigilance behaviour. Photo: Hanna Sungaila.
For so many of us, in so many ways, the past year has been profoundly challenging. For the Vancouver Island Marmot, a species recovering from the brink of extinction in the remote sub-alpine of its namesake island, every year has been a challenge, and this year has been … basically okay?
The Vancouver Island Marmot (Marmota vancouverensis) is a large ground squirrel with the distinction of being British Columbia’s only endemic mammal. It is a sub-alpine species, living in meadows and talus fields, typically above 1,000 metres in elevation (Figure 1). During the short sub-alpine summer, marmots must forage, wean pups, and evade predation by cougars, wolves, and golden eagles. By fall, they must be prepared to survive seven months of winter, hibernating underground.
“During the short subalpine summer, marmots must forage, wean pups, and evade predation by cougars, wolves, and golden eagles.”
Figure 2. A captive-bred marmot is released to the wild. Photo: Adam Taylor
The marmot’s long hibernation takes a significant toll on their body. They lose a third of their body weight, and need to re-invigorate their metabolism and digestive functions even as they dig out of their hibernaculum. For female marmots, the burden of rearing young compounds the challenges of regaining body condition. To cope, marmots do not start reproducing until they are relatively old (three to four years of age), and wean small litters of just three to four pups, with a tendency to skip years between litters.[1] This helps them recover body condition between the dual demands of reproduction and hibernation.
In the 1990s, despite living in a remote ecosystem that has largely escaped direct modification by humans, the marmot population crashed, and the species teetered on the edge of extinction. The cause of the marmot’s endangerment is not completely understood. Core marmot habitat has remained intact, and yet landscape changes on Vancouver Island impacted the marmot profoundly.[2] Logging created population sinks as dispersing marmots set up new colonies in cut blocks, only to be predated as trees regrew. Elk and deer herds began browsing cut blocks at higher elevations, drawing predators into marmot habitat more frequently. Expanding road networks may have made it easier for predators to access the marmot’s colonies. Introduced cottontail rabbits attracted a resident population of golden eagles, who are efficient marmot hunters. Even in the protected wilderness of Strathcona Provincial Park, a hydroelectric dam severed dispersal routes that had sustained colonies on either side of the newly formed Buttle Lake.
A partnership was formed to implement recovery in 1999, and it continues to this day. It includes landowners, the British Columbia government, and the Calgary and Toronto zoos. A new organization was created to lead on-the-ground recovery actions and monitor the wild marmots: the Marmot Recovery Foundation.
“Many significant challenges lie ahead in the marmots’ recovery. The wild population is still tiny.”
This partnership worked to safeguard the species by bringing some marmots into captivity, which also facilitated a captive-breeding and reintroduction program. Captures began in 1997 and focused on rescuing marmots from high-risk locations, such as cut blocks. In the wild, however, the population decline continued. By early 2003, fewer than thirty Vancouver Island Marmots remained in the wild. Fortunately, that same year, the first zoo-born marmots were ready for release into the wild (Figure 2). Of the four marmots released, three were predated by a cougar, and the lone survivor was brought back into captivity for its protection. But releases continued in subsequent years, and the methodology was informed by the program’s successes and failures.
Improving survival of those captive-bred marmots was critical to get the recovery started. Even when they weren’t predated, captive-bred marmots had higher rates of mortality during winter, and delayed breeding when they did survive. Careful monitoring using radio-telemetry, visual surveys, and cameras pointed the Foundation to a surprising conclusion: releasing younger marmots earlier in the year ultimately improved both overwinter survival rates and future reproductive success – despite exposing the marmots to months and even years of predation risk.3 With new release strategies, colonies in the southern part of the marmot’s range, the Nanaimo Lakes region, quickly started to grow (Figure 3). The Foundation turned its attention further north, to Strathcona Provincial Park.
Figure 3. Foundation staff use radiotelemetry to survey a colony for marmots. Photo: Adam Taylor
At first glance, Strathcona appears ideally suited for marmots. It was historically a core part of their range, habitat seems abundant, and it is protected within the boundaries of B.C.’s oldest provincial park. But that analysis conceals some harsh truths. Historic colony sites in the park were situated at higher elevations, experienced longer winters, and the marmots themselves had been absent for a longer time before recovery efforts began. For the marmots, this meant that their refuge burrows and hibernacula, critical components of their habitat that are used for generations, were either absent or in disrepair. The shorter summers and harder winters gave released marmots less time to prepare for a more difficult hibernation. Captive-bred marmots were not nearly as successful in the park, and struggled to gain a sustained foothold that would help them re-establish their burrows and hibernacula.
One small group of marmots, however, did seem to do better in the harsher park environment: wild-born marmots translocated from the colony on Mount Washington. This observation led to the development of an approach where captive-bred marmots are “stepping-stoned” into the Strathcona Provincial Park after they survive one year of “marmot school” living in the wild colony on Mount Washington.[4] There they learn how to use marmot terrain, interact with other marmots, and hibernate in the wild. Research has shown these captive-bred marmots have much better survival odds when released into Strathcona park. This has enabled the marmots to begin the process of re-establishing, and even expanding, colonies in this incredible mountain landscape.
At the end of 2020, appr oximately two hundred wild Vancouver Island Marmots were hibernating in over twenty colonies. Marmots have been re-introduced to historic habitats in Strathcona and Clayoquot Plateau provincial parks, and reoccupied many former colonies in the Nanaimo Lakes region (Figure 4). Reproduction has been high for two consecutive years, and overwinter survival continues to be strong.
Figure 4. Today, most colonies of Vancouver Island marmots are found in the (a) Strathcona and (b) Nanaimo Lakes regions of Vancouver Island.
As we prepare for the 2021 field season, we believe there is reason for cautious optimism. But it is important to note that optimism does need temperance. Many significant challenges lie ahead in the marmots’ recovery. The wild population is still tiny, just two-hundred individuals, and they are terribly vulnerable. A bad weather year, a skilled predator, or a new disease, could derail the species’ recovery. Climate change poses an ongoing challenge as advancing treelines further transform the marmots’ alpine meadows into young forest.[5]
Overcoming these challenges will take a vast amount of work, and no small part of luck. This year will be another in that effort, but it won’t be the last. Still, even a glimmer of genuine hope for a species once so close to extinction is something to hold onto. We can make a difference for the marmots, and for other species in existential peril, if we try.
AUTHOR
Adam Taylor is the Executive Director for the Marmot Recovery Foundation. Cheyney Jackson is the Field Coordinator for the Marmot Recovery Foundation.
References
[1] Bryant, A.A. Reproductive rates of wild and captive Vancouver Island marmots (Marmota vancouverensis). Canadian Journal of Zoology, 83, 664-673 (2005).
[2] Environment and Climate Change Canada. Recovery Strategy for the Vancouver Island Marmot (Marmota vancouverensis) in Canada. Species at Risk Act Recovery Strategy Series. 16 pp. + 41 pp. (2020).
[3] Jackson, C.L., Schuster, R., Arcese, P. Release date influences first-year site fidelity and survival in captive-bred Vancouver Island marmots. Ecosphere, 7(5), (2016).
[4] Lloyd, N.A., Hostetter, N.J., Jackson, C.L., Converse, S.J., Moehrenschlager, A. Optimizing release strategies: a stepping-stone approach to reintroduction. Animal Conservation, 22(2), 105-115, (2019).
[5] Jackson, M.M. et al. Expansion of subalpine woody vegetation over 40 years on Vancouver Island, British Columbia, Canada. Canadian Journal of Forest Research. 46(3), 437-443, (2016)