Game Range Ramblin's
Game Range Articles
by Mike Thompson,
FW&P wildlife biologist,
writing for the Pathfinder
August 24, 2000
Seeley Swan Pathfinder
Seeley Lake, Montana
by Mike Thompson,
If you're a Montanan, it seems there's nothing worth talking about this summer except fire, drought and smoke. Prior to that first, ominous, July lightning storm, however, we were devoting a lot of ink in this column to the poor survival of our elk calves across west-central Montana, and the possible causes for it.
Is anyone wondering what effect this fire season in western Montana might have on elk calf survival?
Researchers in Yellowstone National Park collected data on this very subject during and after the firestorm of 1988. Remember, 1988 was the last time we heard reports of extreme fire behavior, tremendous walls of flame and acts of nature beyond human control. In the midst and aftermath of this sometimes terrifying event, radio-collared elk calves roamed the Park.
In fact, 29 elk calves had been captured and radio-collared in the spring of 1988, only a few weeks before the great fire started. Yet, 85% of these elk calves survived the blaze through summer and fall. It was a higher calf survival rate than was documented in the summer before the fire, or in the two summers following the fire. Predation by bears in the first few days following birth was the most common source of calf mortality in the spring-summer period. Somehow, the radioed calves managed to dodge the flames, but faced a more formidable foe that winter.
You see, the drought and fire of 1988 was followed by a severe winter in 1988-89 in Yellowstone Park. And, it didn't help that 27% of the winter range had burned. Only 16% of the radioed elk calves that entered the winter survived to see their first birthdays. This was by far the lowest winter survival rate documented in the four-year study. Most winter losses were due to starvation. Only one case of winter predation (by a mountain lion) on elk calves was documented. (This was before wolves were returned to Yellowstone.)
Researchers captured and radioed a fresh crop of 36 elk calves in the spring of 1989 and another 32 calves in 1990. Predation rates doubled after the fire of 1988. Before the fire, about 13% of the radioed calves were killed by predators in their first year of life. In the two years after the fire, the predation rate increased to 29%.
The study concluded that the fire increased the vulnerability of calves to predation in the first two years after the burn. This was explained by a decline in the amount of shrub cover in calving areas, which made it easier for spring predators, primarily grizzly and black bears, to find newborn elk.
In summary, elk responded to the drought, fire and severe winter of 1988-89 in several ways. They migrated to winter range about 4-6 weeks earlier than usual in 1988, due to a lack of forage on summer range from both fire and drought. Cows gave birth later than usual in the spring of 1989, probably due to poor physical condition. Elk calves were born lighter than usual, which predisposed them to poor survival. And, as mentioned earlier, newborn calves were hidden in reduced cover, which probably increased their vulnerability to predators.
The Yellowstone study that I'm using as a reference did not follow the fates of elk calves into the period of forage and cover rejuvenation that occurred in the 1990s. I would expect the short-term, negative effects of the fire to be overwhelmed in the long-run by a beneficial increase in forage production, forage quality and cover growth. In the long-run, fire is generally a tonic for elk habitat. But, as we know too well, it can be a very expensive tonic. Expensive by various measures.
How might this study in Yellowstone Park apply to the Spread Ridge-Upper Monture fire area?
First, I would suggest that it is another good indicator that elk are pretty adept at escaping direct injury from fire, even under the extreme circumstances that occurred in Yellowstone in 1988. With the possible exception of some unlucky individuals, there is no reason to expect a significant loss of elk to the flames of our local backcountry fires so far this summer.
Second, I think it emphasizes the importance of the coming winter in determining how much of a short-term impact the drought and fire will have on next year's calf survival. If it takes a deep-snow winter to break this drought cycle, then I'll cheer it on along with everyone else. But, based on the Yellowstone research, elk will suffer if a hard winter comes on the heels of this dry summer. Fortunately, we've not seen any critical winter range burn yet in the Blackfoot-Clearwater valleys, which gives our elk an edge over the Yellowstone herd in 1988.
Have we lost cover for newborn elk calves in the Monture and Spread drainages? Sure we have in the short-run. But, unlike the Yellowstone fires, our local fires are not burning in areas where lots of elk give birth to lots of calves. Our calving areas tend to be at lower elevation. So, I doubt that the loss of calving cover will contribute to much of an increase in predation on newborn elk calves.
The way things look to me so far, I'll predict that we're likely to gain the long-term benefits of fire as an enhancement to elk habitat without having to experience the same short-term losses that were documented after the 1988 fires in Yellowstone.
As always, winter is the wild card. And, in the case of fire, the next big wind could change everything. It helps us prepare to think ahead, but in the end, we'll all just have to wait and see.