Structure and Distribution of a Kodiak Bear Population

Troyer, Willard A.; Hensel, Richard J.

doi:10.2307/3798793

Cited by 27 publications

(13 citation statements)

References 2 publications

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“…In each case, the integrity of the litter was maintained for the entire period of observation and no mortalities occurred. These findings correspond with those for grizzly populations on Kodiak Island (Troyer and Hensel, 1964) and in Glacier National Park, Canada (Mundy and Flook, 1973), but are in contrast to first year mortality of 39 per cent in Yellowstone National Park (Craighead and Craighead, 1967).…”

Section: Litter Size and Maternal Relationshipssupporting

confidence: 85%

“…The mean computed density of one grizzly per 8.2 square miles was intennediate to those of other populations studied with generally comparable methods. Troyer and Hensel (1964) observed one grizzly per 0.6 square miles during an aerial census of shrubby habitats on Kodiak Island, Alaska. In contrast, Jonkel and Cowan (1971) found a density of about one grizzly per 13 square miles on an area of extensive coniferous forests adjacent to Glacier National Park using a combination of marking and direct observations.…”

Section: Density and Sizementioning

confidence: 97%

“…The trend shown by observation frequency was reflected by a slightly larger size of yearling as compared to cub litters. Litter sizes for other populations ranged from 1.58 in the Yukon Territory, Canada (Pearson, 1972), to 2.36 for the hunted population in Alaska (Troyer and Hensel, 1964).…”

Section: Litter Size and Maternal Relationshipsmentioning

confidence: 99%

“…Craighead and Craighead (1971) and Mundy and Flook (1973) found mean increments of 19 and 18 per cent cubs, respectively, for Yellowstone National Park and Glacier National by guest on June 9, 2016 http://jmammal.oxfordjournals.org/ Downloaded from Park, Canada. A mean increment of 22 per cent was described for a hunted grizzly population on Kodiak Island (Troyer and Hensel, 1964).…”

Section: Sex and Age Compositionmentioning

confidence: 99%

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Population Characteristics of Grizzly Bears in Glacier National Park, Montana

Martinka¹

1974

Journal of Mammalogy

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Grizzly bears (Ursus arctos) were studied in Glacier National Park, Montana, from 1967Montana, from through 1971. Annual samples of density permitted total park population estimates that ranged from 175 to 230 grizzlies. Mean population composition was 49, 19, 17, and 15 per cent unclassified adults, productive females, cubs, and yearlings, respectively. Production of cubs varied from year to year. Comparable litter sizes for cubs (1.7) and yearlings (1.8) suggested a low mortality rate for cubs. Differences in productivity between years appeared related to variations in length of maternal relationships. Social structure was characterized by a predominance of single individuals and family groups. Other groupings resulted from mating behavior, maintaining the integrity of litters following dissolution of the maternal bond, unusual relationships, or response to preferred food sources. A mean mortality of 1.8 grizzlies per year resulted from management to protect park visitors. Mortality in areas immediately adjacent to the park is summarized. Population regulation and the impact of human activity on the population are discussed.

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Section: Litter Size and Maternal Relationshipssupporting

confidence: 85%

Section: Density and Sizementioning

confidence: 97%

Section: Litter Size and Maternal Relationshipsmentioning

confidence: 99%

Section: Sex and Age Compositionmentioning

confidence: 99%

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Population Characteristics of Grizzly Bears in Glacier National Park, Montana

Martinka¹

1974

Journal of Mammalogy

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“…On a 96 square mile sub unit of the Kodiak National Wildlife Refuge 160 different bears were identified, to give a population density of 1 per 384 a c r e s (Troyer & Hensel 1964). This is the greatest density reported for an a r e a of this size in any part of the world.…”

mentioning

confidence: 99%

The Status and Conservation of Bears (Ursidae) of the World: 1970

Cowan¹

1972

Bears: Their Biology and Management

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

Bled

Belant

Daele

et al. 2017

Ecology and Evolution

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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.

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Structure and Distribution of a Kodiak Bear Population

Cited by 27 publications

References 2 publications

Population Characteristics of Grizzly Bears in Glacier National Park, Montana

Population Characteristics of Grizzly Bears in Glacier National Park, Montana

The Status and Conservation of Bears (Ursidae) of the World: 1970

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

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