Grizzly Bears in the Pacific Northwest: A Natural History (Part 4)
Recovery came swiftly to the Yellowstone and Northern Continental Divide Ecosystems, unfortunately the same could not be said of the North Cascades. Like the glaciers that move so slowly, grinding their way through the high country, the North Cascades Ecosystem (NCE) Recovery Plan has moved no faster than the glaciers. One could even argue that with the increased melting of the glaciers due to climate change the glaciers are now moving faster than the grizzly recovery project.
The North Cascades Recovery Zone differed from Yellowstone and Glacier because when the recovery zones were established, the North Cascades had much fewer numbers than the other two parks in the recovery zone. As stated above the last grizzly sighting on the American side of the North Cascades was in 1996. Occasionally a track in the mud will be found, but it is estimated now that ten or fewer bears inhabit the North Cascades Ecosystem.
This lack of a viable population presents several problems for potential recovery. Grizzlies are very slow reproducers with an average life expectancy of 25 years. One may think that 25 years is a rather long lifespan in comparison to most wild mammals, giving them plenty of chances each year to reproduce. But when looking at some of the evolutionary habits of the grizzly we start to see that 25 years might not be enough to increase the population.
A female grizzly will not start mating until the age of 5 – 8 years. When the female finally does mate, she will spend 3 to 4 years with her cubs. The average female bear will only mate 2 or 3 times in her life. Survival of cubs is yet another concern. A female grizzly will normally have two cubs of which, under typical environmental circumstances, only one will survive. Grizzly cubs have to face the challenge of eluding other predators such as cougars, wolves, and even other male grizzlies. Male grizzlies have been known to kill cubs that aren’t theirs in order to ensure that their own offspring carries on. Also, in an ecosystem where there may be less than 10 other grizzlies it can be very difficult just to find a mate, considering that grizzlies have a large range of up to 500 square miles.
This grim outlook of very few bears spread out over nearly 10,000 square miles in the United States and another 3,800 in the Canadian North Cascades makes natural recovery seem next to impossible. Evidence shows that a viable population in the North Cascades Ecosystem is 200 to 400 bears. To obtain this number the ecosystem would need at least 70 bears to begin working toward a viable population, and we aren’t even close to that number. So, if natural recovery seems to be such a long shot, then what is the other option?
With an estimated 10 or fewer bears, the agencies involved in the recovery efforts have to consider augmentation, bringing in bears from other ecosystems. However, several problems exist with augmentation. One might assume that Alaska, with a population of over 30,000 brown bears would be able to spare plenty. The problem with this scenario is that if bears from Alaska were brought into the North Cascades Ecosystem they would not survive very long. Alaskan brown bears have a diet rich in fat and protein from plentiful salmon runs in late summer. Alaskan brown bears can reach up to 1500 lbs. In the North Cascades and other land-based ecosystems bears rely heavily on berries and other forms of vegetation and will weigh up to 700 lbs. A bear in the North Cascades will have a diet consisting of 90 – 95% vegetation. Alaskan brown bears simply could not adapt that quickly to the fat and protein deficiency faced in the North Cascades Ecosystem.
This shows that if augmentation were to occur in the North Cascades, bears would have to be brought in from a similar ecosystem. That means that the potential area must have the same food sources as the North Cascades. This immediately eliminates Yellowstone, which has a population of cutthroat trout that supply grizzlies with a high amount of protein in the fall prior to hibernation. Yellowstone also has a dense wolf population that also greatly benefits grizzlies. Where a large wolf pack will fend off a grizzly from its kill, a smaller pack or a lone wolf can be easily chased away by the much larger grizzly. Whereas Washington does have wolves, the population is very small and very few of them are located in the grizzly recovery zone, so their impact on grizzlies would be minimal, at least for many years.
The ecosystem most closely related to the North Cascades is The Northern Continental Divide Ecosystem (NCDE). According to the U.S. Fish and Wildlife Service the NCDE has a population of approximately 1000 grizzlies, so this would seem like a good option, right? The problem here is that in taking 70 bears out of the NCDE and placing them in another would be a huge hit for that ecosystem. It would basically be like having 7% of that ecosystem’s bear population killed. A removed bear from an ecosystem is ultimately a dead bear in that ecosystem. With this in mind the Cabinet-Yak Ecosystem with an estimated population of 25 bears and the Selkirk ecosystem with 50 – 70 can also be thrown out. The Northern Rockies have done a wonderful job in managing their grizzly population. Before wildlife managers in the North Cascades start asking the Northern Rockies for some of their bears and spending money on transportation, policy, and monitoring programs, maybe they should take a look at what has made the Northern Rockies so successful up to this point and rethink their strategy.
Mike has also written Part One, Part Two, and Part Three of this series along with a series on wolves.