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Victor G. Barnes

Publications and source records attributed to Victor G. Barnes.

12 recordsLinked to original sources
USGS2017

Using multiple data types and integrated population models to improve our knowledge of apex predator population dynamics

Current management of large carnivores is informed using a variety of parameters, methods, and metrics; however, these data are typically considered independently. Sharing information among data types based on the underlying ecological, and recognizing observation biases, can improve estimation of individual and global parameters. We present a general integrated population model (IPM), specifically designed for brown bears ( Ursus arctos ), using three common data types for bear ( U . spp.) populations: repeated counts, capture–mark–recapture, and litter size. We considered factors affecting ecological and observation processes for these data. We assessed the practicality of this approach on a simulated population and compared estimates from our model to values used for simulation and results from count data only. We then present a practical application of this general approach adapted to the constraints of a case study using historical data available for brown bears on Kodiak Island, Alaska, USA. The IPM provided more accurate and precise estimates than models accounting for repeated count data only, with credible intervals including the true population 94% and 5% of the time, respectively. For the Kodiak population, we estimated annual average litter size (within one year after birth) to vary between 0.45 [95% credible interval: 0.43; 0.55] and 1.59 [1.55; 1.82]. We detected a positive relationship between salmon availability and adult survival, with survival probabilities greater for females than males. Survival probabilities increased from cubs to yearlings to dependent young ≥2 years old and decreased with litter size. Linking multiple information sources based on ecological and observation mechanisms can provide more accurate and precise estimates, to better inform management. IPMs can also reduce data collection efforts by sharing information among agencies and management units. Our approach responds to an increasing need in bear populations’ management and can be readily adapted to other large carnivores.

Ecology and Evolution↗
USGS2003

Reproductive maturation and senescence in the female brown bear

Changes in age-specific reproductive rates can have important implications for managing populations, but the number of female brown (grizzly) bears ( Ursus arctos ) observed in any one study is usually inadequate to quantify such patterns, especially for older females and in hunted areas. We examined patterns of reproductive maturation and senescence in female brown bears by combining data from 20 study areas from Sweden, Alaska, Canada, and the continental United States. We assessed reproductive performance based on 4,726 radiocollared years for free-ranging female brown bears (age ≥3); 482 of these were for bears ≥20 years of age. We modeled age-specific probability of litter production using extreme value distributions to describe probabilities for young- and old-age classes, and a power distribution function to describe probabilities for prime-aged animals. We then fit 4 models to pooled observations from our 20 study areas. We used Akaike's Information Criterion (AIC) to select the best model. Inflection points suggest that major shifts in litter production occur at 4-5 and 28-29 years of age. The estimated model asymptote (0.332, 95% CI = 0.319-0.344) was consistent with the expected reproductive cycle of a cub litter every 3 years (0.333). We discuss assumptions and biases in data collection relative to the shape of the model curve. Our results conform to senescence theory and suggest that female age structure in contemporary brown bear populations is considerably younger than would be expected in the absence of modern man. This implies that selective pressures today differ from those that influenced brown bear evolution.

Ursus↗
USGS1999

Evaluations of plastic mesh tubes for protecting conifer seedlings from pocket gophers in three western states

The efficacy of plastic mesh tubes for protecting conifer seedlings from pocket gopher damage was evaluated on three national forest lands in three states. In each area, cohorts of 640 protected seedlings and 640 unprotected seedlings (3,840 total) were individually monitored for damage, survival, and growth twice each summer for 5 yr after planting. Substantial differences were found between protected and unprotected seedlings for time until occurrence of damage, survival time, proportion damaged and proportion surviving, as well as differences in growth. Over the three forest study sites, the proportion of unprotected seedlings damaged ranged from 60-89%, whereas the proportion of protected seedlings damaged after 5 yr ranged from 18-27%. The proportion of unprotected seedlings that died of gopher damage over 5 yr ranged from 46-64%, versus 1-19% for protected seedlings. Height growth was 25% greater for protected seedlings. Even when only undamaged seedlings were considered, protected seedlings exhibited superior height growth, possibly due to a more favorable microclimate provided by the tubes. These results were reflected in the higher and more uniform stocking rates for protected seedlings.

Western Journal of Applied Forestry↗
USGS1998

Double-stocking for overcoming damage to conifer seedlings by pocket gophers

A 5-yr study was conducted on national forests in Idaho and Oregon to evaluate how doubling the seedling stocking rate of lodgepole pine ( Pinus contorta ) would relate to 5-year survival and the uniformity of distribution of seedlings in the presence of northern pocket gopher ( Thomomys talpoides ) damage. Either 4 or 8 seedlings were planted in 40-m 2 subplots (1000 or 2000 seedlings/ha) and monitored for gopher damage. We found that the number of seedlings attacked by gophers, and consequently, the number of seedlings surviving for 5 years, were directly proportional to the stocking rate, but the consistency of seedling distribution within each site (as measured by the proportion of 40-m 2 subplots with ≥ 2 surviving seedlings) did not double with stocking rate. In some situations, increasing the stocking rate should be considered as a method for overcoming pocket gopher damage.

Idaho, Oregon↗
USGS1998

Responses of brown bears to human activities at O'Malley River, Kodiak Island, Alaska

We classified levels of direct response of brown bears ( Ursus arctos middendorffi ) to aircraft, watercraft, and groups of people on the O'Malley River area of Kodiak Island, Alaska. General public use occurred on the area in 1991 and 1993, whereas structured bear viewing programs used the area in 1992 and 1994. Brown bears displayed high (running) or moderate (walking away) response on 18 (48%) occasions when fixed-wing aircraft flew over the animals <100 m above ground. Three of 4 helicopter flights <200 m overhead and 9 interactions with watercraft at ≤200 m distance also elicited strong response. Encounters between people and bears resulted in strong responses from bears more frequently (37%, n = 134) during years of general public use than in years of structured bear viewing (6%, n = 72, P < 0.0001). We suggest that higher levels of low or neutral response by bears to encounters with guided bear viewing groups was the result of consistent and predictable patterns of human activity.

Alaska↗
USGS1997

Effect of vegetation management for reducing damage to lodgepole pine seedlings from northern pocket gophers

The effects of vegetation management on northern pocket gopher ( Thomomys talpoides ) activity and damage to lodgepole pine ( Pinus contorta ) seedlings were studied using 2,4-D herbicide to alter the habitat. Treatments were applied to a large (8.1 ha) treatment unit and observed effects were compared with an untreated control unit of the same size. The greatly reduced forb and grass cover on the treated unit was associated with a corresponding decrease in pocket gopher activity that persisted for 6 years after initial treatment. Times until seedlings first incurred gopher damage and overall survival of seedlings were greatly increased on the treated unit.

Oregon↗
USGS1995

Vegetation management for reducing mortality of ponderosa pine seedlings from Thomomys spp

The effects of vegetation management on Mazama pocket gopher activity and damage to ponderosa pine seedlings were studied using atrazine herbicide to alter the habitat. Atrazine treatments were applied to a large treatment unit and observed effects were compared to an untreated control unit. The greatly reduced forb and grass cover on the treated unit was associated with a corresponding decrease in pocket gopher activity. Times until seedlings first incurred gopher damage and overall survival of two cohorts of seedlings were greatly increased on the treated unit.

Crop Protection↗
USGS1995

Kodiak brown bears

Brown bears ( Ursus arctos middendorffi ) on the Kodiak Archipelago are famous for their large size and seasonal concentrations at salmon streams. Sport hunting of Kodiak bears has been popular since World War II. Their value as captivating subjects to observe or photograph is a more recent development that is increasing rapidly; visitors from around the world come to experience brown bears on Kodiak, adding substantially to Alaska's economy. An equally important contribution of brown bears is their value as an indicator of ecosystem vitality. Despite high population numbers, Kodiak bears are vulnerable to the environmental effects that have seriously depleted brown bear populations in Europe and parts of North America (Cowan 1972; Servheen 1990). They are long-lived mammals that require large expanses of land to meet biological needs, and their low reproductive rate limits population recovery. Energy development, depletion of salmon resources, and recreational growth are factors that can adversely affect bears and, in doing so, signal a loss of environmental quality affecting many species. Management of Kodiak brown bears is directed at maintaining current density, distribution, and habitat-use patterns. This goal is challenged by growing levels of commercial and private use throughout the region. An immediate concern is cabin and lodge development on 121,500 ha (300,000 acres), formerly part of the Kodiak National Wildlife Refuge, that were deeded to Alaska Natives via the Alaska Native Claims Settlement Act. Much of that Native-conveyed land is coastal or riparian habitat especially important to brown bears during summer and fall. Concurrently, recreational use of the Kodiak refuge is increasing about 10% annually (USFWS 1987). Sport fishing, bear photography, and deer and elk hunting often put bears and humans in direct conflict (Smith et al. 1989). Timber harvest on Afognak Island, uncertain trends of salmon populations due to natural or human-caused events (e.g., Exxon Valdez oil spill), and hydroelectric development (Smith and Van Daele 1990) could impose additional long-term effects on localized bear populations.

Alaska↗
USGS1994

Brown bear-human interactions associated with deer hunting on Kodiak Island

I compared distribution and range of brown bears ( Ursus arctos middendorffi ) with temporal and spatial distribution of Sitka black-tailed deer ( Odocoileus hemionus sitkensis ) hunting activity on westside Kodiak Island, Alaska, to examine impacts of deer hunting on bears. Mean number of bears that annually ranged ≤5 km from the coast, >5 km inland from the coast, or in both areas was 10, 8, and 11, respectively. Bears that exclusively or seasonally occupied the coast zone were usually classed as having moderate or high potential to interact with hunters because most hunter access and effort (>95%) was via the coast. Bears that ranged exclusively inland were considered unlikely to encounter hunters. Animals that ranged in both zones often (39%) moved inland during fall (Oct-Dec) and most bears (70%) denned in the inland zone. Females that denned near the coast entered dens later (x̄ = 22 Nov) than females that denned inland (x̄ = 12 Nov). Two radio-collared bears were known to raid deer-hunting camps and 9 other marked bears were observed by hunters or were located <200 m from hunting camps. Deer-hunter surveys revealed that more than two-thirds of the deer harvest occurred during October-November. About half of the hunters observed at least 1 bear during their hunt. Seven to 21% of the respondents reported having a threatening encounter with a bear and 5-26% reported losing deer meat to bears. Human-induced mortality to radio-collared bears occurred more often near the coast (5) than inland (3); 7 bears were harvested by sport hunters and 1 was killed (nonsport) in a Native village. Deer hunters killed 2 unmarked females in defense of life or property situations in the study area. High bear densities and concentrated deer-hunting activity combine to make conflicts unavoidable. Adverse impacts to bears can be minimized by maintaining low levels of human activity in inland areas and improving hunter awareness of bear ecology and behavior.

Alaska↗
USGS1975

Movements, home range, and control of porcupines in western Washington.

Radio-telemetry was used to monitor the movements of 18 porcupines (Erethizon dorsatum) in typical west Cascase habitat near Mount St. Helens, Washington. Average linear movement ranged from 249 m in 24 hr to 1,585 m for periods of more than 30 days. The greatest linear movement was 31.1 km in 66 days. Average home range of animals tracked for 10 months or more was 83.5 hectares; the average range of males (106.6 hectares) exceeded that of females (81.2 hectares). Concentration of animals at den sites was not observed. Hunting porcupines with dogs is probably the most effective control measure.

Wildlife Leaflet↗