Federal scientists have concluded there are 624 grizzly bears on Alaska's Kenai Peninsula, or at least they believe there were 624 bears there at some point in 2010. Maybe.
The problem, they confess, is that grizzly bears are hard to count. They roam vast home ranges. They are often hidden from view in alder thickets. Anti-social by evolutionary design, they do not gather into bands or easily-counted herds. And, if all that weren't enough, their populations tend toward significant seasonal variability.
Reaching that 624 bear took two years of genetic fingerprinting of 11,175 samples of bear hair from 145 barbed-wire hair traps scattered throughout 70 percent of the bear habitat on the Kenai Peninsula, south of Alaska’s largest city. It is estimated to include 200 boars, 200 sows, and 224 cubs -- and that's just one of the places things begin to get complicated.
Few cubs survive
Cub survival is a wild card in the bear world. A study done in Denali National Park and Preserve found 65 percent of Denali cubs die. Other research would indicate that's near normal in the wilds of the 49th state.
Applying a 65 percent mortality rate for cubs in the study based on hair samples collected over a month in June 2010 could result in a bear population as low as 480 bears by fall of that year. And then, too, there is the variability around the 624 number itself. It's the highest probability point in a population range from 504 bears to 772 bears, cubs included.
"It's challenging to study bears," said Gino Del Frate, an Alaska Department of Fish and Game biologist, who nearly 15 years ago estimated the Kenai population at 140 to 280 grizzlies. At the time, there were concerns the Kenai bears might be threatened by extinction. The bears appeared few in number and largely cut off from the rest of Alaska by the fjord-like waters of Turnagain Arm.
Fears of an isolated, inbred bear population have fallen over the years as genetic studies found what appears to be only a small bottleneck in gene mixing between Kenai and mainland bears. Tracking radio-collared bears has demonstrated the Arm apparently doesn’t pose a large impediment to movement.
The bears had once been thought to need the isthmus of land near the community of Portage that connects the Kenai to the rest of Alaska, but it appears that Kenai bears -- being good swimmers and unafraid of the legendary, foot-sucking mud of the Arm -- can cross to the mainland elsewhere.
Concerns about a vulnerable population of Kenai grizzlies did, however, lead to tight restrictions on Kenai Peninsula hunting in the years since Del Frate's population estimate, and there are indications bear numbers might have increased despite a large number of shootings in defense of life and property (DLP). It is legal for Alaskans to shoot bears in self-defense, and in some years a lot of bears have died that way on the Kenai. There were about 40 DLP kills in 2008, for instance.
A kill of that size would have triggered a decline in the grizzly population then estimated between 200 and 350 bears, but state officials said they saw no such thing. If anything, it appears bear numbers were tracking steadily upward.
Some say too many grizzlies
Conflicts between humans and what is publicly perceived to be a growing bear population has even led some to contend there are now too many grizzlies on the Kenai.
The new population number -- from the paper authored by researchers John Morton of the Kenai National Wildlife Refuge, Gregory Hayward of the Chugach National Forest, and others -- would argue otherwise.
"Our estimate of the Kenai brown bear population is generally consistent with estimates of brown bear density in Interior, rather than coastal Alaska," wrote Morton, the lead author. The Interior, with its food-short ecosystem due to extremely cold winters and a limited growing season -- is not known for supporting vast populations of bears. With bountiful runs of salmon and a warmer climate, the Kenai would at first blush appear more like the Alaska Peninsula or the state's Panhandle, where previous studies have found bear densities four to 10 times as great as that calculated for the Kenai.
Where's the bear habitat?
Those areas, Hayward said in an interview with Alaska Dispatch, would appear to have a lot more good bear habitat than the Kenai. Stand back and look at a map of the Kenai Peninsula, he said, and you see a lot of glaciers, a lot of mountain tops, and a lot of water -- none of which can support bears.
"Think about the Kenai," Hayward said. "There is a fair amount of country that is inland." He described the habitat there as "mediocre." As a result, bears tend to move toward the salmon-rich lowlands, which also attract people. The concentration of people and bears in the same area could easily make it appear there are more bears than the peninsula-wide number suggests.
But it would also appear there are more bears than in the past.
"Our density estimate is more than twice the 20-bears-per-1,000-square-kilometers that was assumed when Del Frate suggested that the brown bear population on the Kenai Peninsula was 250 to 300 individuals," Morton wrote. "We emphasize that the approach Del Frate used to estimate the Kenai brown bear population in 1999 was logical at the time for management purposes and laudably conservation-minded.
"We caution that these two values (the new estimate and the old) should not be compared to make inferences regarding population growth as the earlier value was a reasonable guess and the current value is a model-based estimate using empirical data.
"Other than increasing DLPs, which is confounded by an increasing human population, we have no empirical data to suggest that the brown bear population on the Kenai Peninsula has increased in the last two decades."
Still, as Del Frate noted in an interview, if one were to take the 1999 estimate and apply a reasonable rate of growth for the bear population over the past 15 years, the number arrived at would be near the estimate in the latest census. The longtime biologist has always categorized his number as a gross estimate, but added "I always thought I could defend the number I created."
Hair traps and genetic fingerprinting
Now there is a new number, about which Hayward, the Chugach National Forest scientist, says much the same thing despite difficulties that included the placement of hair traps and the fact the genetic fingerprinting identified only 353 to 539 specific bears.
Hayward said he is comfortable with the way the study finally came together and the extrapolation to a range of 504 to 772 with a spotlight on 624. That 624 number was used instead of a range because the five scientists involved thought a range might confuse people, Hayward said.
The 624 number might, however, confuse them even more, given that anyone who knows anything about the business of counting bears knows a population cannot be counted this precisely.
Still, everyone agrees, 624 is now the best number available.
"It's the most objective number to date," said Larry VanDaele, the regional supervisor for Fish and Game's Division of Wildlife Conservation and a man with extensive experience in studying the oversize grizzlies called Kodiak Island brown bears.
"It's one piece of the puzzle," he said. "It's not exactly the way we would have done it, (but) management of brown bear populations is rarely done by a specific number."
Hayward called the methodology behind the new study, which has not been peer reviewed, "strong and very sound." VanDaele and other state officials, who are largely responsible for managing the bears on the Kenai, don’t take issue with that.
"The number is what it is," Del Frate said.
Though bears are hard to count, it is often obvious when they are rare, as they once appeared to be on the Kenai Peninsula. A couple decades ago, for instance, grizzlies were uncommon along the popular, salmon-rich Russian River. Now they’re plentiful enough there that they attract Outside visitors coming north to "live among the bears."
Too few or too many?
Local residents are of two views on this. Some think it a wonderful wilderness experience to have a lot of bears around. Others think the bears a very real threat to domestic animals and pets, and sometimes to humans.
There were two fatal maulings on the Kenai in 1990, and though there have been no deaths since, there have been several serious injuries.
Some consider it a miracle angler Dan Bigley survived a 2003 attack that left him blind after a bear ripped off the front of his face. A bear attacked and seriously injured an employee of the Kenai Princess Lodge in 2008. An attack just last fall put another man in the hospital.
Bears killed for safety
Alaska Fish and Game again this summer, as in past years, was forced to kill a number of bears due to public safety concerns. The state is largely responsible for managing the bears. As in other U.S. states, state wildlife authorities set seasons and bag limits for how many animals hunters can kill, although there is one difference in Alaska.
In a situation unique to the 49th state, federal courts empowered federal officials to intervene in the name of subsistence hunting, basically a system of preferential rights for locals. At the moment, subsistence grizzly bear hunts are limited to residents of Ninilchik, but could spread to other communities. Ninilchik is a community of 880 along the Sterling Highway between Kenai and Homer, about 100 miles south of Anchorage.
The local economy is largely based on tourism, and sport and commercial fishing.
The subsistence kill of Kenai grizzlies these days is tiny, but the trophy kill has grown into double digits and some people would like to see it expanded. The state Board of Game, which sets hunting regulations, will take up Kenai bear hunting in March.
The new study is likely to play a key role in influencing the outcome of those proposals. How that works out in the end will probably depend in significant part on how various interest groups end up interpreting the work of the scientists. At the end of the day, the study can be read to say there are not all that many bears on the Kenai, at least by Alaska standards, or that there is a large and healthy population.
Contact Craig Medred at craig(at)alaskadispatch.com
CORRECTION: An earlier version of this story included an incorrect reference to an ongoing study by a state biologist looking at the Kenai grizzly population.