Bears are afraid of bicyclists. That's why they typically run or remain hidden when they hear or see a cyclist heading their way. Paradoxically, that's also why attacks by grizzly bears are increasing. Grizzlies seldom attack people but may attack in self-defense when surprised at close range.
Prior to 2000, only four cyclists had been attacked by bears, all grizzlies, in North America. Since 2000 at least 19 attacks — including, surprisingly, collisions — have occurred, averaging about one per year, with both grizzly and black bears involved.
No cause to overreact. Many more people are seriously injured or killed by stinging insects. But we shouldn't ignore the trend either. Mountain biking on trails — particularly narrow, singletrack trails – is increasingly popular in natural areas, including many areas inhabited by grizzly bears.
With that threat in mind, Anchorage's Basher Community Council passed a resolution in February unanimously asking the municipal parks department to forgo trail development in a portion of Far North Bicentennial Park. The area, about 160 acres, straddles Basher Road between North Bivouac Trailhead and Stuckagain Heights.
In 2009 the park Trail Improvements Plan designated several areas where no new trails would be built, partly because it would increase risk of bear-human encounters. However, that plan allows trail development in the parcel the Basher Community Council hopes to protect from more trails.
Where the bikers are
Maybe it's a good time to reconsider where bikers want to build new trails, where the bears need to be, and why the areas of overlap can be danger zones.
An interactive map posted on the Internet last year by Strava compiled the cumulative track-lines of 10 million bikers and others who use smartphones and Fitbits. News articles revealed the potential for terrorists to use Strava's Global Heatmap to digitally reconnoiter potential ambush routes of U.S. service members who download their recreational and exercise routes.
Strava's app, which may have been used to plan attacks by terrorists, can also be used to prevent attacks by bears.
For example, you can zoom in on the Anchorage Bowl and Chugach State Park and see every trail used by Strava subscribers. The "heat" signature depends on intensity of use, with the most popular trails appearing white-hot. Judging from their heat signatures, some trails are more heavily used than others.
To use Strava's map, ignore the obvious roads — like Elmore Road to the west and Abbott Road south of the park — which are recorded primarily by phones and Fitbits carried by motorists. Focus on the trails illuminated by users in Bicentennial Park. Note the dense cluster of bright, squiggly lines in the southeast corner of the park. Those singletrack trails, built in 2008, are among the most heavily used trails in the park.
You can also discern Basher Road, which leads to the looping roads in Stuckagain Heights after cutting a swath through FNBP and bisecting the small parcel in question.
Where the bears are
We know much less about where bears are. Bears don't wear Fitbit activity trackers or carry smartphones.
But several studies in the past couple of decades help illustrate where bears tend to hang out and how they move in and around the Anchorage Bowl, especially Far North Bicentennial Park. All of the studies were conducted or supervised by Sean Farley, a wildlife physiologist with the Alaska Department of Fish and Game. Much of this information had not been analyzed when the 2009 park trails plan was being finalized.
A detailed insight into grizzly bear movements was obtained with GPS collars in the late 2000s. Most of the 11 collared bears denned in Chugach State Park. Grizzlies were much less likely to enter neighborhoods. But the north and south forks of Campbell Creek in Far North Bicentennial Park were an obvious magnet to many of the collared bears.
Surprisingly, the core home ranges of several of the bears were located in Far North Bicentennial Park.
The park is surrounded on three sides by urban development, but on the east side it's connected to natural habitat in Chugach State Park and Joint Base Elmendorf-Richardson. Stuckagain Heights is the only neighborhood along the east boundary of of Far North Bicentennial Park. A mile-wide gap exists between Stuckagain Heights and the nearest neighborhoods to the north and south. According to Farley's research, these two gaps are the primary routes used by grizzlies in and out of the park.
A map from Farley's report shows the movements of three collared grizzlies through the two gaps. To illustrate movements, Farley connected each consecutive location point with a straight line. Obviously, bears don't travel in straight lines, but the clusters of lines show the areas bears tend to move through and the areas they tend to avoid.
Farley and his colleagues also collected hair samples snagged by tree bark and underbrush in several locations in the Anchorage Bowl. By analyzing stable isotopes in the hairs of individual bears, Farley found that 43 percent of the diet of the collared grizzlies that visited streams during the study was composed of salmon. Clearly, Far North Bicentennial Park attracts grizzlies by the presence of many spawning salmon in late summer and fall.
In addition to the collared bear movement data, DNA signatures led Farley to conclude that at least 20 different grizzly bears had visited Far North Bicentennial Park during the study.
Avoiding unnecessary togetherness
With more than 100 miles of maintained trails, the park attracts over a million visits annually. Recreational use is not uniform, however. According to the 2009 park trails plan, intensity of use is low in the natural area that Basher Community Council hopes to put off limits to new trail development.
Strava's heat map also shows where trails are not currently heavily used. Two "blacked-out" areas stand out in Bicentennial Park. These areas — the most infrequently used by humans — match the areas heavily used as movement corridors by grizzly bears.
Twenty or thirty years ago the trails in the southeast corner of the park were primarily used by cross-country skiers in winter and a few runners and hikers in summer. As trail biking, especially on singletrack, increased in popularity, more trails were built in that corner of the park. Now most of the southern gap between Prospect Heights and the South Fork of Campbell Creek is heavily used by bikers and other trail users, and even more new trails are proposed.
We don't have GPS collar data showing how the bears have adjusted to the new trails. Some bears are more risk-averse than others. The wariest bears may have shifted their travel routes across the South Fork to avoid the bikers. So what happens when that option is also foreclosed by new trails?
Because singletrack bikers like hills, and suitable areas are not abundant in the Anchorage Bowl, a lot of attention is being focused on the section where Basher Community Council hopes to forestall new trail development.
If singletrack proponents build more trails in those areas, the bears won't stop using Bicentennial Park. They need the fish. What will happen is that bears, bikers and other trail users will come into contact more often. There will be more surprise encounters. Grizzly bears don't like to be surprised. Which means more people and more bears will be hurt or killed. Is that what we want to happen?
Rick Sinnott is a former Alaska Department of Fish and Game wildlife biologist. The views expressed here are the writer's own and are not necessarily endorsed by Alaska Dispatch News. Contact him at firstname.lastname@example.org.
The views expressed here are the writer's and are not necessarily endorsed by the Anchorage Daily News, which welcomes a broad range of viewpoints. To submit a piece for consideration, email commentary(at)adn.com. Send submissions shorter than 200 words to email@example.com or click here to submit via any web browser.