Michael L. Gibeau

Rates and causes of grizzly bear mortality in the interior mountains of British Columbia, Alberta, Montana, Washington, and Idaho

Trends of grizzly bear (Ursus arctos) populations are most sensitive to female survival; thus, understanding rates and causes of grizzly bear mortality is critical for their conservation. Survival rates were estimated and causes of mortalities investigated for 388 grizzly bears radiocollared for research purposes in 13 study areas in the Rocky and Columbia mountains of Alberta, British Columbia, Montana, Idaho, and Washington between 1975 and 1997. People killed 77-85% of the 99 grizzly bears known or suspected to have died while they were radiocollared. In jurisdictions that permitted grizzly bear hunting, legal harvest accounted for 39-44% of the mortalities. Other major causes of mortality included control killing for being close to human habitation or property, self-defense, and malicious killings. The mortality rate due to hunting was higher (P = 0.006) for males than females, and subadult males had a higher probability (P = 0.007) of being killed as problem animals than did adult males or females. Adult females had a higher (P = 0.009) mortality rate from natural causes than males. Annual survival rates of subadult males (0.74-0.81) were less than other sex-age classes. Adult male survival rates varied between 0.84 and 0.89 in most areas. Survival of females appeared highest (0.95-0.96) in 2 areas dominated by multiple-use land and were lower (0.91) in an area dominated by parks, although few bears were killed within park boundaries. Without radiotelemetry, management agencies would have been unaware of about half (46-51%) of the deaths of radiocollared grizzly bears. The importance of well-managed multiple-use land to grizzly bear conservation should be recognized, and land-use plans for these areas should ensure no human settlement and low levels of recreational activity.

Hair cortisol concentration as a noninvasive measure of long-term stress in free-ranging grizzly bears (Ursus arctos): considerations with implications for other wildlife

Human-caused landscape change negatively affects the sustainability of many wildlife populations. In Alberta, Canada, grizzly bears (Ursus arctos L., 1758) live in one of the most populated and heavily exploited landscapes in which the species survives. Long-term physiological stress in individual animals may be the predominant mechanism linking landscape change with impaired wildlife population health. Hair cortisol concentration has been validated as a biomarker of long-term stress in humans and domestic animals; however, limited work has examined factors that may affect its meas- urement or interpretation. We have measured cortisol in as few as five guard hairs of a grizzly bear and have identified factors influencing hair cortisol concentration in this species. Hair cortisol varies with hair type, body region, and capture method. It is not influenced by colour, age, sex, environmental exposure (18 days), or prolonged laboratory storage (>1 year) and does not vary along the length of the hair shaft. Recommendations for prudent use of hair cortisol analysis in grizzly bears are discussed with implications for the development of hair cortisol concentration as a tool to monitor long-term stress in other wildlife.

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.

Uncontrolled field performance of Televilt GPS-Simplex™ collars on grizzly bears in western and northern Canada

Abstract Commercially available telemetry collars for wildlife that employ Global Positioning System (GPS) devices generally have the ability to gather a large volume of precise location data. We appraised the performance of 12-channel Televilt GPS-Simplex™ collars (Televilt/TVP Positioning AB, Lindesberg, Sweden) deployed across western and northern Canada on grizzly bears (Ursus arctos). Of 71 collar deployments between 2000 and 2002, 38 were retrieved and performed according to their programmed schedule, 20 were retrieved and had some degree of failure, and 13 experienced catastrophic failures and were not retrieved. In addition to these deployments, 10 collars failed predeployment. GPS collar fix success rates were greater for the retrieved collars from the Northwest Territories than for the 4 study areas in British Columbia and Alberta (F4,50 = 10.82, P < 0.001); thus, the latter areas were grouped for further analyses. Collar fix success rates in the British Columbia and Alberta study areas differed between the retrieved collars that functioned normally (x̄ = 65%, SE = 2.3, n = 28) and collars retrieved with failure events (x̄ = 56%, SE = 4.3, n = 17; t43 = 2.09, P = 0.043). Fix success rates were lower the longer collars were in the field (rs = −0.35, n = 45, P = 0.020). Locations from the GPS collars had a mean dilution of precision of <4 for 2D and 3D locations and thus had a good degree of precision. We were satisfied with the volume and quality of the location data; however, we advise other researchers that significant time and money may be lost troubleshooting problems with the Televilt Simplex system. Other recommendations for future and current users are considered.

Estimating Grizzly and Black Bear Population Abundance and Trend in Banff National Park Using Noninvasive Genetic Sampling

We evaluated the potential of two noninvasive genetic sampling methods, hair traps and bear rub surveys, to estimate population abundance and trend of grizzly (Ursus arctos) and black bear (U. americanus) populations in Banff National Park, Alberta, Canada. Using Huggins closed population mark-recapture models, we obtained the first precise abundance estimates for grizzly bears ( = 73.5, 95% CI = 64–94 in 2006;  = 50.4, 95% CI = 49–59 in 2008) and black bears ( = 62.6, 95% CI = 51–89 in 2006;  = 81.8, 95% CI = 72–102 in 2008) in the Bow Valley. Hair traps had high detection rates for female grizzlies, and male and female black bears, but extremely low detection rates for male grizzlies. Conversely, bear rubs had high detection rates for male and female grizzlies, but low rates for black bears. We estimated realized population growth rates, lambda, for grizzly bear males ( = 0.93, 95% CI = 0.74–1.17) and females ( = 0.90, 95% CI = 0.67–1.20) using Pradel open population models with three years of bear rub data. Lambda estimates are supported by abundance estimates from combined hair trap/bear rub closed population models and are consistent with a system that is likely driven by high levels of human-caused mortality. Our results suggest that bear rub surveys would provide an efficient and powerful means to inventory and monitor grizzly bear populations in the Central Canadian Rocky Mountains.

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.

Brown Bear Population Trends from Demographic and Monitoring-based Estimators

Abstract A primary goal of monitoring wildlife populations is the estimation of population growth rate, λ. Two common methods by which biologists estimate λ are demographic studies of marked individuals, which tend to be expensive and labor-intensive, and estimators derived from time series of population indices. We compare grizzly bear (Ursus arctos) population growth rates in the Banff ecosystem (Alberta, Canada) from a published demographic study to estimates from concurrent monitoring of an index of population size, the number of females with cubs-of-the-year (Fcub). We estimated population trends by transforming the index into 2 population estimators (bias-corrected Chao and summation), and used each to estimate λ. The 95% confidence intervals of λ̂ from the 2 monitoring-based estimators overlapped the point estimate of the demographic study. Precision of the bias-corrected Chao estimator was very low (95% CI of λ  =  0.572–1.679); its application to the time-series used here is essentially fruitless. Precision of the summation estimator (95% CI of λ  =  0.847–1.137) and the demographic study (0.99–1.09) were higher, but the CI of the former at least could be artificially narrow. Because all estimates were close to 1.00, the long-term fate of this population may depend critically on subtle changes in growth rate and on environmental stochasticity. Given that long-term demographic studies are not feasible in this system, population monitoring may be a worthwhile way to assess population dynamics. However, given the low power of many monitoring techniques to detect trends and the low precision of the Fcub estimators in particular, long time-series and explicit measures to remove sampling variance should be employed to increase trend estimate precision.

Non-invasive genetic sampling of brown bears and Asiatic black bears in the Russian Far East: A pilot study

Abstract Non-invasive genetic sampling (NGS) methods have been instrumental in providing robust population abundance and density estimates of bears. We conducted a small pilot study to (1) evaluate 2 NGS methods of hair traps and bear rubs in the Russian Far East (RFE) on sympatric populations of Asiatic black bears (Ursus thibetanus) and brown bears (Ursus arctos), and (2) to identify potential DNA marker sets for future study. Genetic analysis required 6 microsatellite markers to definitively identify individuals plus a gender marker, and closed population models estimated 142 Asiatic black bears and 18 brown bears. Spatially-explicit mark–recapture (SECR) density estimates for brown bears were 3 bears/100 km2. Inflated Asiatic black bear estimates resulted from a lack of recaptures, although using combined detection data from the 2 NGS methods was found to improve precision for abundance estimates. Capture probabilities were higher for brown bears than for Asiatic black bears, but overall recapture probabilities were low for both species. The frequency of rubbing declined from June to August, possibly due to bears leaving the study area, and Asiatic black bears were detected less frequently on rubs than brown bears, suggesting that species-specific ecology must be incorporated into future study designs. We recommend that future applications of NGS in the RFE improve capture probabilities by sampling earlier in the season to mitigate geographic closure violation for abundance estimates and to increase the number of detections for robust spatially explicit capture–recapture analyses. Our results demonstrate that NGS methods have strong potential for monitoring of bear populations in the RFE.