Grizzly Bear Activity in Response to Traffic Volume and Road Densities

By Jordan Schaul | National Geographic | November 21, 2012

Contributing Editor Dr. Jordan Schaul reports on the first study to examine grizzly bear behavior in response to spatial and temporal variations in traffic patterns using traffic models.

In April, while filming a segment for the BBC series Dangerous Roads with actor Charley Boorman, I reported on the impact of roads on wildlife for Nat Geo News Watch.

Vehicle-wildlife collisions were of particular interest to the producers of the BBC television series.  For the Alaskan version of Dangerous Roads, a camera crew was deployed to follow Charley on a road trip from Anchorage toward Prudhoe Bay along the Seward Highway—one of the most dangerous highways in North America.

The BBC stopped by the Alaska Wildlife Conservation Center on their trip north to visit with our staff and animals. They asked if we had any “statistics” on the number of orphans that had been brought to the Center as a result of collisions with vehicles on the Seward Highway.  Indeed, we provided homes for moose calves, bear cubs, and other wildlife, orphaned as a result of road incidents, but not all of the incidents occurred on that particular highway.  Hence, we couldn’t provide a valid estimate.

Grizzly and black bear cubs of the year and older cubs were often brought to our facility, particularly during Spring when offspring were just emerging from hibernacula for the first time or otherwise still dependent on their mothers.  Vehicle collisions either killed their mothers or left the sows in conditions that required they be immediately dispatched (euthanized).

Although a busy time for us, the implications stemming from such vehicle-wildlife incidents have a great influence on the conservation of species worldwide, including here in North America where we are relatively adept at managing wildlife in the context of road interactions.

Data on vehicle-associated wildlife mortalities may or may not be astonishing, but wildlife conservationists consider roadkill so much a threat to species survival that they have begun looking for solutions through an emerging discipline known as road ecology.

Some of our most iconic species succumb to road-associated incidents. In fact, some species like the woodland caribou are threatened more by road collisions than by habitat loss. And at one point when Florida panthers were truly on the brink of extinction, half of the extant population succumbed to vehicle collisions.

Roads present more than just the potential for dangerous interactions between vehicles and wildlife; they fragment habitat and restrict the movement of wildlife species.  Although many wildlife management and transportation agencies have worked to mitigate vehicle-associated incidents with wildlife on our roadways, there is still much to learn about the ways in which wildlife interact with roads.

We do know that behavioral responses to roads can be species-specific, age-specific, and even gender-specific. We also know that behavior may also shift based on the time of day and season.

What does this all mean for the grizzly bear, since most grizzly bear mortalities occur near roads and current management programs aimed at protecting grizzly bears focus on limiting road densities?

While bears may use roads and roadsides to travel and are sometimes attracted to roads because of the presence of ungulate roadkill and other attractants, they also avoid roads because of vehicular activity levels.

To adequately develop effective bear management programs, which have focused primarily on limiting road densities, an understanding of how bears respond to traffic volumes on the roads is also needed, according to a new study.

Although previous studies have used indirect indicators of traffic levels to assess bear activity on and near roadways, it is only recently that investigators have used more precise model estimates of traffic volume to examine the behavior of grizzly bears in response to vehicular activity.

Joe Northrup and his colleagues at the University of Alberta, Edmonton, and the University of Calgary documented the response of grizzlies to vehicular traffic in a recent issue of the Journal of Applied Ecology (British Ecological Society). In the paper entitled “Vehicular Traffic Shapes Grizzly Bear Behaviour on a Multi-use Landscape”, the authors noted that roads themselves are not so detrimental to wildlife, and grizzly bears in particular, but that the human use of roads is what needs to be examined.

The authors created models of road use for an entire road network in southwestern Alberta, Canada, and documented for the first time the response of grizzly bears to a wide range of spatial and temporal traffic patterns. They hypothesized that “traffic would significantly influence grizzly bear habitat selection and movement near roads and that bears would avoid roads with higher traffic volumes.”

What they found was that bears avoided roads with high and medium traffic volumes and instead used low traffic volume roads and crossed these low volume roads with greater frequency.  They also found that bears utilized private agricultural land over multi-use public land. The agricultural land was typically higher in road density, but lower in traffic volume.

Northrup said, “the finding that traffic had a greater impact on bear behavior than road density is important for how we manage bears. Typically management plans focus on limiting road density, but with increasing industrial development in bear habitat, this is becoming difficult. Incorporating measures aimed at reducing traffic, such as access management, into these plans will be an important step for bear conservation.”


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Jordan Carlton SchaulWith training in wildlife ecology, conservation medicine, and comparative psychology, Dr. Schaul's contributions to Nat Geo Voices have covered a range of environmental and social topics. He draws particular attention to the plight of imperiled species highlighting issues at the juncture or nexus of sorta situ wildlife conservation and applied animal welfare. Sorta situ conservation practices are comprised of scientific management and stewardship of animal populations ex situ (in captivity / 'in human care') and in situ (free-ranging / 'in nature'). He also has a background in behavior management and training of companion animals and captive wildlife, as well as conservation marketing and digital publicity. Jordan has shared interviews with colleagues and public figures, as well as editorial news content. In addition, he has posted narratives describing his own work, which include the following examples: • Restoration of wood bison to the Interior of Alaska while (As Animal Curator at Alaska Wildlife Conservation Center and courtesy professor at the University of Alaska) • Rehabilitation of orphaned sloth bears exploited for tourists in South Asia (As executive consultant 'in-residence' at the Agra Bear Rescue Center managed by Wildlife SOS) • Censusing small wild cat (e.g. ocelot and margay) populations in the montane cloud forests of Costa Rica for popular publications with 'The Cat Whisperer' Mieshelle Nagelschneider • Evaluating the impact of ecotourism on marine mammal population stability and welfare off the coast of Mexico's Sea of Cortez (With Boston University's marine science program) Jordan was a director on boards of non-profit wildlife conservation organizations serving nations in Africa, North and South America and Southeast Asia. He is also a consultant to a human-wildlife conflict mitigation organization in the Pacific Northwest. Following animal curatorships in Alaska and California, he served as a charter board member of a zoo advocacy and outreach organization and later as its executive director. Jordan was a member of the Communication and Education Commission of the International Union for the Conservation of Nature (CEC-IUCN) and the Bear Specialist Group of the IUCN Species Survival Commission (BSG-SSC-IUCN). He has served on the advisory council of the National Wildlife Humane Society and in service to the Bear Taxon Advisory Group of the Association of Zoos and Aquariums (AZA Bear TAG). In addition, he was an ex officio member of the council of the International Association for Bear Research and Management.