Grizzly bear selection of managed and unmanaged forests in the Selkirk Mountains

2003 ◽  
Vol 33 (5) ◽  
pp. 822-829 ◽  
Author(s):  
Robert B Wielgus ◽  
Pierre R Vernier
Keyword(s):  
Goodness Of Fit ◽  
Ursus Arctos ◽  
Negative Impact ◽  
Small Sample ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Managed Forests ◽  
Selkirk Mountains ◽  
Young Forests ◽  
Small Sample Sizes

We tested the commonly held hypotheses that grizzly bears (Ursus arctos) select against clearcuts and young forests and select for natural openings and old forests in the Selkirk Mountains from 1986 to 1991. We compared use versus availability using χ2 goodness-of-fit for 11 bears (five females, six males) in a south study area containing both open roads (public use allowed) and closed roads (no public use allowed) and 11 bears (seven females, four males) in a north study area containing restricted roads (forestry use only). Zero of 11 females and 1 of 11 males (1/22 bears) selected against (P < 0.05) clearcuts. Five of 11 females and 2 of 11 males (7/22 bears) selected against (P < 0.05) young forests. The apparent selection against young forests appeared to be due to selection against associated open roads, not against young forests themselves. Forestry activities alone (managed forests and restricted roads) appeared to have no negative impact on grizzly bear habitat use. Because of small sample sizes, pooling of seasonal data, and lack of experimental replication, our results should not be extrapolated until similar studies are conducted elsewhere.

A grizzly bear from the Middle Wisconsin of Woodbridge, Ontario

1976 ◽  
Vol 13 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Charles S. Churcher ◽  
Alan V. Morgan
Keyword(s):  
Ursus Arctos ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Bone Fragment ◽  
Mammuthus Primigenius ◽  
Ursus Arctos Horribilis ◽  
Before And After ◽  
Lake Simcoe ◽  
Left Humerus ◽  
Woolly Mammoth

The distal end of the left humerus of a grizzly bear, Ursus arctos, has been recovered from above the Early Wisconsin Sunnybrook Till at Woodbridge, Ontario, from the same horizon that previously has yielded remains of the woolly mammoth, Mammuthus primigenius. The age of these specimens is estimated at 40 000–50 000 years BP, within the mid-Wisconsin, Port Talbot Interstadial. The only other recognized Canadian record of a grizzly bear east of Manitoba is from a gravel sequence at Barrie, near Lake Simcoe, Ontario, dated from a bone fragment to 11 700 ± 250 years BP. A specimen recovered in Toronto in 1913 from an Early Wisconsin horizon is also considered to represent the grizzly. Bears of the grizzly type, Ursus arctos-horribilis were present in Ontario before and after the Early and Late Wisconsin ice advances.

On the use of chi-square analyses in studies of resource utilization

1991 ◽  
Vol 21 (1) ◽  
pp. 58-65 ◽  
Author(s):  
Dennis E. Jelinski
Keyword(s):  
Resource Utilization ◽  
Goodness Of Fit ◽  
Small Sample ◽  
Homogeneity Test ◽  
Type I ◽  
Sample Sizes ◽  
Goodness Of Fit Test ◽  
Chi Square ◽  
Test Of Homogeneity ◽  
Small Sample Sizes

Chi-square (χ2) tests are analytic procedures that are often used to test the hypothesis that animals use a particular food item or habitat in proportion to its availability. Unfortunately, several sources of error are common to the use of χ2 analysis in studies of resource utilization. Both the goodness-of-fit and homogeneity tests have been incorrectly used interchangeably when resource availabilities are estimated or known apriori. An empirical comparison of the two methods demonstrates that the χ2 test of homogeneity may generate results contrary to the χ2 goodness-of-fit test. Failure to recognize the conservative nature of the χ2 homogeneity test, when "expected" values are known apriori, may lead to erroneous conclusions owing to the increased possibility of committing a type II error. Conversely, proper use of the goodness-of-fit method is predicated on the availability of accurate maps of resource abundance, or on estimates of resource availability based on very large sample sizes. Where resource availabilities have been estimated from small sample sizes, the use of the χ2 goodness-of-fit test may lead to type I errors beyond the nominal level of α. Both tests require adherence to specific critical assumptions that often have been violated, and accordingly, these assumptions are reviewed here. Alternatives to the Pearson χ2 statistic are also discussed.

Predation on moose and caribou by radio-collared grizzly bears in east central Alaska

1988 ◽  
Vol 66 (11) ◽  
pp. 2492-2499 ◽  
Author(s):  
R. D. Boertje ◽  
W. C. Gasaway ◽  
D. V. Grangaard ◽  
D. G. Kelleyhouse
Keyword(s):  
Important Implication ◽  
Rangifer Tarandus ◽  
Ursus Arctos ◽  
Prey Availability ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
East Central ◽  
Specific Factors ◽  
Low Levels ◽  
Predation Rates

Radio-collared grizzly bears (Ursus arctos) were sighted daily for approximately 1-month periods during spring, summer, and fall to estimate predation rates. Predation rates on adult moose (Alces alces) were highest in spring, lowest in summer, and intermediate in fall. The highest kill rates were by male grizzlies killing cow moose during the calving period. We estimated that each adult male grizzly killed 3.3–3.9 adult moose annually, each female without cub(s) killed 0.6–0.8 adult moose and 0.9–1.0 adult caribou (Rangifer tarandus) annually, and each adult bear killed at least 5.4 moose calves annually. Grizzly predation rates on calves and grizzly density were independent of moose density and are probably more related to area-specific factors, e.g., availability of alternative foods. An important implication of our results is that managers should not allow moose densities to decline to low levels, because grizzlies can have a greater relative impact on low- than on high-density moose populations and because grizzly predation can be difficult to reduce. Grizzly bears were primarily predators, rather than scavengers, in this area of low prey availability (11 moose/grizzly bear); bears killed four times more animal biomass than they scavenged.

A study of predominant aerobic microflora of black bears (Ursus americanus) and grizzly bears (Ursus arctos) in northwestern Alberta

1987 ◽  
Vol 33 (11) ◽  
pp. 949-954 ◽  
Author(s):  
L. J. Goatcher ◽  
M. W. Barrett ◽  
R. N. Coleman ◽  
A. W. L. Hawley ◽  
A. A. Qureshi
Keyword(s):  
Soil Bacteria ◽  
Ursus Arctos ◽  
Random Distribution ◽  
Ursus Americanus ◽  
Black Bear ◽  
Black Bears ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Streptococcus Species ◽  
Generic Composition

Swab specimens were obtained from nasal, rectal, and preputial or vaginal areas of 37 grizzly and 17 black bears, captured during May to June of 1981 to 1983, to determine the types and frequency of predominant aerobic microflora. Bacterial genera most frequently isolated from bears were Escherichia, Citrobacter, Hafnia, Proteus, Staphylococcus, and Streptococcus species, comprising about 65% of the isolates. Erwinia, Xanthomonas, Agrobacterium, Rhizobium, and Gluconobacter/Acetobacter were also isolated but at lower frequencies (< 5%). Comparison of bacterial generic composition using similarity quotient values showed no appreciable differences between grizzly and black bear flora. Also, no outstanding differences in bacterial generic composition were observed among grizzly bear samples; however, differences were noted among black bear samples. Fungal genera most commonly encountered included Cryptococcus, Rhodotorula, Cladosporium, Penicillium, Sporobolomyces, and Candida. In general, the microflora of both bear types were marked by generic diversity and random distribution. The majority of microorganisms isolated from the plant samples in the study area were also found in bear samples. This observation and the presence of certain water and soil bacteria in samples from bears suggest that the predominant microflora of both grizzly and black bears were transient and probably influenced by their foraging habits and surrounding environments.

scholarly journals A Meta-Analysis Shows That Screen Bottom Boards Can Significantly Reduce Varroa destructor Population

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 624
Author(s):  
Fang Liu ◽  
Xinjian Xu ◽  
Yuan Zhang ◽  
Hongxia Zhao ◽  
Zachary Y. Huang
Keyword(s):  
Apis Mellifera ◽  
Honey Bee ◽  
Varroa Destructor ◽  
Negative Impact ◽  
Meta Analysis ◽  
Small Sample ◽  
Effect Sizes ◽  
Negative Results ◽  
Mite Control ◽  
Small Sample Sizes

Varroa destructor is by far the most serious threat to the western honey bee, Apis mellifera. A screen bottom board, a cultural method for mite control, is a modified bottom board with a screen that allows mites to fall onto a sticky board, or the grass or soil below the screen. Whether or not a screen bottom board can reduce varroa significantly has been controversial. Most studies show a trend of lower varroa populations in colonies with these boards, but the results are usually not statistically significant. To understand whether the negative results have been due to small sample sizes, or because the board is actually ineffective, we conducted a meta-analysis with seven published studies with a total of 145 colonies. Meta-analysis showed that the confidence intervals of the combined effect sizes were negative with a Hedges’ g of −1.09 (SE 0.39, 95% CI −2.0 to −0.19, p < 0.01), which suggests that the varroa population in colonies with screen bottom boards is significantly lower compared to those with traditional wooden floors. We thus conclude that the screen bottom board does have a significantly negative impact on the varroa population and can be part of tool kits for mite control.

Grizzly bear digging sites for Hedysarum sulphurescens roots in southwestern Alberta

1984 ◽  
Vol 62 (12) ◽  
pp. 2571-2575 ◽  
Author(s):  
Anne C. Holcroft ◽  
Stephen Herrero
Keyword(s):  
Discriminant Function ◽  
Discriminant Function Analysis ◽  
Ursus Arctos ◽  
Function Analysis ◽  
Soil Surface ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Rock Fragments ◽  
Ursus Arctos Horribilis ◽  
Steep Slopes

Characteristics of sites where Hedysarum sulphurescens Rydb. roots were extensively, less extensively, or not dug by grizzly bears Ursus arctos horribilis Ord. were analyzed in relation to topographic, vegetative, soil, and geologic features. Discriminant function analysis significantly separated dug and undug sites, but did not separate extensively and less extensively dug sites. Ease of breaking the soil surface, presence of shaly rock fragments, loose cobble and gravel, and steep slopes were characteristic of dug sites. The abundance of H. sulphurescens appeared less important than the loose nature of the substrate indicating that digging time was important in optimizing energetics.

scholarly journals Estimating unrecorded human-caused mortalities of grizzly bears in the Flathead Valley, British Columbia, Canada

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5781
Author(s):  
Bruce N. McLellan ◽  
Garth Mowat ◽  
Clayton T. Lamb
Keyword(s):  
British Columbia ◽  
Ursus Arctos ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Considerable Uncertainty ◽  
The Government ◽  
Reporting Rates ◽  
Gravel Road

Managing the number of grizzly bear (Ursus arctos) mortalities to a sustainable level is fundamental to bear conservation. All known grizzly bear deaths are recorded by management agencies but the number of human-caused grizzly bear deaths that are not recorded is generally unknown, causing considerable uncertainty in the total number of mortalities. Here, we compare the number of bears killed legally by hunters to the number killed by people for all other reasons, for bears wearing functioning radiocollars and for uncollared bears recorded in the British Columbia (BC) government mortality database for the Flathead Valley in southeast BC. Between 1980 and 2016, permitted hunters killed 10 collared bears and 12 (9 known, 3 suspected) were killed by people for other reasons. This ratio differed (p < 0.0001) from the uncollared bears in the government database where 71 were killed by hunters while only 10 were killed for other reasons. We estimate that 88% (95% CI; 67–96%) of the human-caused mortalities that were not by permitted hunters were unreported. The study area may have low reporting rates because it is >40 km on a gravel road from a Conservation Officer office, so reporting is difficult and there are no human residences so there is little concern of a neighbor contacting an officer. Our results are likely indicative of other places that are road-accessed but far from settlements. We discuss the implications of sampling individuals for collaring and the possible implications of wearing a collar on the animal’s fate.

Grizzly bear feeding activity at alpine army cutworm moth aggregation sites in northwest Montana

1998 ◽  
Vol 76 (2) ◽  
pp. 221-227 ◽  
Author(s):  
Don White, Jr. ◽  
Katherine C Kendall ◽  
Harold D Picton
Keyword(s):  
National Park ◽  
Ursus Arctos ◽  
Feeding Activity ◽  
Grizzly Bears ◽  
Glacier National Park ◽  
Grizzly Bear ◽  
Use Patterns ◽  
Ursus Arctos Horribilis ◽  
Early Fall ◽  
Minimum Numbers

Grizzly bears (Ursus arctos horribilis) consume army cutworm moths (Euxoa auxiliaris) from late June through mid-September at alpine moth aggregation sites in Glacier National Park, Montana. To better understand the importance of army cutworm moths to grizzly bears, we determined the sex and age classes and minimum numbers of grizzly bears foraging at known alpine moth aggregation sites, and documented the timing and use patterns of grizzly bears foraging in these areas. A minimum of 36 grizzly bears were observed 106 times feeding at 6 of 9 known moth aggregation sites from late June through mid-September in 1992-1995; no bears were observed on moth sites in 1993. Bears fed on moth aggregations disproportionately more at elevations >2561 m, on slopes between 31° and 45°, and on southwest-facing aspects. Lone adult grizzly bears appeared to be underrepresented and subadults overrepresented at moth sites. Moths are highly digestible; all parts are digested except for the exoskeleton. We propose that army cutworm moths are an important, high-quality, preferred summer and early-fall food for grizzly bears in Glacier National Park. We do not present any data that demonstrate an increase in the importance of moths when other foods fail.

Major components of grizzly bear diet across North America

2006 ◽  
Vol 84 (3) ◽  
pp. 473-489 ◽  
Author(s):  
Garth Mowat ◽  
Douglas C Heard
Keyword(s):  
British Columbia ◽  
North America ◽  
Rangifer Tarandus ◽  
Ursus Arctos ◽  
Nitrogen Isotope ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Carbon And Nitrogen ◽  
Skull Size ◽  
Meat Diet

We measured stable carbon and nitrogen isotope ratios in guard hair of 81 populations of grizzly bears (Ursus arctos L., 1758) across North America and used mixing models to assign diet fractions of salmon, meat derived from terrestrial sources, kokanee (Oncorhynchus nerka (Walbaum in Artedi, 1792)), and plants. In addition, we examined the relationship between skull size and diet of bears killed by people in British Columbia. The majority of carbon and nitrogen assimilated by most coastal grizzly bear populations was derived from salmon, while interior populations usually derived a much smaller fraction of their nutrients from salmon, even in areas with relatively large salmon runs. Terrestrial prey was a large part of the diet where ungulates were abundant, with the highest fractions observed in the central Arctic, where caribou (Rangifer tarandus (L., 1758)) were very abundant. Bears in some boreal areas, where moose (Alces alces (L., 1758)) were abundant, also ate a lot of meat. Bears in dryer areas with low snowfall tended to have relatively high meat diet fractions, presumably because ungulates are more abundant in such environments. Kokanee were an important food in central British Columbia. In areas where meat was more than about a third of the diet, males and females had similar meat diet fractions, but where meat was a smaller portion of the diet, males usually had higher meat diet fractions than females. Females reached 95% of their average adult skull length by 5 years of age, while males took 8 years. Skull width of male grizzly bears increased throughout life, while this trend was slight in females. Skull size increased with the amount of salmon in the diet, but the influence of terrestrial meat on size was inconclusive. We suggest that the amount of salmon in the diet is functionally related to fitness in grizzly bears.

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