Stephen Herrero

Grizzly bear response to human development and activities in the Bow River Watershed, Alberta, Canada

Few studies have reported the effects of multiple human activities on grizzly bears, Ursus arctos. We document the degree of grizzly bear response to various human developments as a function of multiple interacting variables based on observed median distances to roads, trails and development features in a landscape where human presence is widespread. Female grizzly bears remained further than males from paved roads regardless of habitat quality or time of day. Males were found closer to paved roads when within or adjacent to high quality habitat and during the period of least human activity. The combination of traffic volume and highway configuration, however, overrides a bear’s attraction to high quality habitats for high-speed, high-volume, highways. Avoidance of busy transportation corridors was strongest in the adult segment of the population. Bears were found closer to trails during the human inactive period when within high quality habitat and further from trails when distant to high quality habitat. Our data indicated an inverse relationship between the sexes in response to vehicles and traffic noise compared to the response to human settlement and encountering people. Female bears were found further away than males in relation to vehicles and traffic noise, yet found closer than males to human settlement and places where people may be encountered. Those males that were more willing to exploit high quality habitat near roads, did so at night and where hiding cover was present. Adult females were the most risk-averse cohort, choosing to avoid humans instead of seeking out high quality habitats. Adult female grizzly bears were influenced most by human activities and development. Management agencies must maintain access to high quality habitat, especially for adult females, and create new opportunities to support the reproductive potential of the population.

GRIZZLY BEAR DEMOGRAPHICS IN AND AROUND BANFF NATIONAL PARK AND KANANASKIS COUNTRY, ALBERTA

Abstract The area in and around Banff National Park (BNP) in southwestern Alberta, Canada, is 1 of the most heavily used and developed areas where grizzly bears (Ursus arctos) still exist. During 1994–2002, we radiomarked and monitored 37 female and 34 male bears in this area to estimate rates of survival, reproduction, and population growth. Annual survival rates of bears other than dependent young averaged 95% for females and 81–85% for males. Although this area was largely unhunted, humans caused 75% of female mortality and 86% of male mortality. Females produced their first surviving litter at 6–12 years of age (x̄ = 8.4 years). Litters averaged 1.84 cubs spaced at 4.4-year intervals. Adult (≥ 6-years-old) females produced 0.24 female cubs per year and were expected to produce an average of 1.7 female cubs in their lifetime, based on rates of reproduction and survival. Cub survival was 79%, yearling survival was 91%, and survival through independence at 2.5–5.5 years of age was 72%, as no dependent young older than yearlings died. Although this is the slowest-reproducing grizzly bear population yet studied, high rates of survival seem to have enabled positive population growth (λ = 1.04, 95% CI = 0.99–1.09), based on analyses using Leslie matrices. Current management practices, instituted in the late 1980s, focus on alleviating human-caused bear mortality. If the 1970–1980s style of management had continued, we estimated that an average of 1 more radiomarked female would have been killed each year, reducing female survival to the point that the population would have declined.

From the Field: Brown bear habituation to people—safety, risks, and benefits

Abstract Recently, brown bear (Ursus arctos) viewing has increased in coastal Alaska and British Columbia, as well as in interior areas such as Yellowstone National Park. Viewing is most often being done under conditions that offer acceptable safety to both people and bears. We analyze and comment on the underlying processes that lead brown bears to tolerate people at close range. Although habituation is an important process influencing the distance at which bears tolerate people, other variables also modify levels of bear-to-human tolerance. Because bears may react internally with energetic costs before showing an overt reaction to humans, we propose a new term, the Overt Reaction Distance, to emphasize that what we observe is the external reaction of a bear. In this paper we conceptually analyze bear viewing in terms of benefits and risks to people and bears. We conclude that managers and policy-makers must develop site-specific plans that identify the extent to which bear-to-human habituation and tolerance will be permitted. The proposed management needs scientific underpinning. It is our belief that bear viewing, where appropriate, may promote conservation of bear populations, habitats, and ecosystems as it instills respect and concern in those who participate.

Human injury inflicted by grizzly bears

Grizzly bear (Ursus arctos horribilis) attacks resulting in human injury and known to have occurred in the national parks of North America were examined. Fifty-seven attacks in which 61 persons were injured took place in three national parks in the United States and accounted for 79 percent of the known injuries. The remaining 16 injuries occurred in four Canadian national parks. The 77 injured persons gives an injury rate of 1 person per 2 million visitors.

Alaskan brown bears, humans, and habituation

Abstract We present a new paradigm for understanding habituation and the role it plays in brown bear (Ursus arctos) populations and interactions with humans in Alaska. We assert that 3 forms of habituation occur in Alaska: bear-to-bear, bear-to-human, and human-to-bear. We present data that supports our theory that bear density is an important factor influencing a bears overt reaction distance (ORD); that as bear density increases, overt reaction distance decreases, as does the likelihood of bear–human interactions. We maintain that the effects of bear-to-bear habituation are largely responsible for not only shaping bear aggregations but also for creating the relatively safe environment for bear viewing experienced at areas where there are high densities of brown bears. By promoting a better understanding of the forces that shape bear social interactions within populations and with humans that mingle with them, we can better manage human activities and minimize bear–human conflict.

A proposed lexicon of terms and concepts for human-bear management in North America

Abstract We believe that communication within and among agency personnel in the United States and Canada about the successes and failures of their human–bear (Ursidae) management programs will increase the effectiveness of these programs and of bear research. To communicate more effectively, we suggest agencies clearly define terms and concepts used in human–bear management and use them in a consistent manner. We constructed a human–bear management lexicon of terms and concepts using a modified Delphi method to provide a resource that facilitates more effective communication among human–bear management agencies. Specifically, we defined 40 terms and concepts in human–bear management and suggest definitions based on discussions with 13 other professionals from the United States and Canada. Although new terms and concepts will emerge in the future and definitions will evolve as we learn more about bear behavior and ecology, our purpose is to suggest working definitions for terms and concepts to help guide human–bear management and research activities in North America. Applications or revisions of these definitions may be useful outside of North America.

Are black bears a factor in the restoration of North American grizzly bear populations

Abstract We assess the potential for American black bears (Ursus americanus) to limit the growth of colonizing or severely reduced grizzly bear (Ursus arctos) populations. Managers are faced with the challenge of increasing the size of small (N < 75) grizzly bear populations in the North Cascade, Selkirk, Cabinet–Yaak, and Bitterroot recovery areas of the USA and Canada. These populations are mainly limited by human-caused mortality. However, other factors such as competition from black bears could impose additional constraints. Brown and grizzly bears and American black bears evolved separately until about 13,000 years ago and, as a probable consequence, they can have substantial diet overlap. Where meat and roots are available, grizzly bears consume more of these foods than do black bears. Where fleshy fruits and succulent forbs are the primary high quality bear foods, as in the North Cascade, Selkirk, and Cabinet–Yaak ecosystems, dietary overlap between grizzly and black bears can be almost complete. Largely because they are smaller, black bears can exist at roughly 10 times the density of grizzly bears, use ranges that are, on average, four-fifths smaller, and are more efficient than grizzly bears at using low densities of small berries. We postulate that the primary impact of black bears on grizzly bears is through reduced reproduction and recruitment caused by exploitation competition, despite the documented ability of most grizzly bears to dominate most black bears during physical confrontations. Such an effect would be greatest in areas where both species rely on berries and forbs, where grizzly bear populations have been extirpated, substantially reduced, or are absent but within dispersal distance, and where black bear populations are comparatively robust. On this basis we postulate that exploitation competition by resident black bears, together with mortality caused by Native Americans, slowed or even curbed the invasion of grizzly bears east across North America during the late Pleistocene and early Holocene. We also postulate that grizzly bears are absent on some coastal islands within dispersal distance of robust grizzly bear populations because of competitive exclusion by black bears.

Distribution of subadult grizzly bears in relation to human development in the Bow River Watershed, Alberta

Abstract We studied the relationship between human development and activity, and subadult grizzly bears (Ursus arctos) by comparing the distribution of radiotelemetry locations from 23 subadult versus 29 adult grizzly bears during 1994–2000 in the Bow River Watershed of Alberta, Canada. We used logistic regression to model significant differences in the spatial distribution of subadult and adult grizzly bears and analysis of variance (ANOVA) to test for significant differences in temporal distribution. Subadult bears were significantly closer to high-use roads and at lower elevations than adult bears. Both subadult and adult bears were significantly closer to high-use roads and at lower elevations during human inactive periods (1800–0700) than during human active periods (0700–1800). Subadult bears were closer to high-use roads regardless of the time of day, and therefore predisposed to greater encounter rates with humans. Consequently, subadult bears had a greater chance of becoming habituated to humans and of being killed or removed from the population by humans than adult bears. In areas with high levels of human use, we recommend that grizzly bear managers consider the population effects of these losses.

Are canadian foxes swift enough

Abstract In 1983, the swift fox Vulpes velox was reintroduced to the Canadian prairie, after an absence of 45 years. We counter recent criticism of our efforts by Stromberg & Boyce (1986). Our initial breeding stock originated from Colorado and South Dakota. From those animals we have developed a successful captive breeding programme in Canada. The goal of our captive breeding programme is to maximise genetic heterogeneity. Once animals are released, natural selection over subsequent generations will produce locally adapted genotypes. Contrary to Stromberg and Boyce, we feel that our reintroduction programme is based on principles of sound genetic management. We do not believe that our efforts will diminish the genetic composition of what appears to be rare populations of swift fox in the northern United States.