Lactation, hibernation, and mass dynamics of American black bears and grizzly bears

1995 ◽  
Vol 73 (12) ◽  
pp. 2216-2222 ◽  
Author(s):  
Sean D. Farley ◽  
Charles T. Robbins
Keyword(s):  
Mass Loss ◽  
Black Bear ◽  
Milk Composition ◽  
Ash Content ◽  
Milk Intake ◽  
Black Bears ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
American Black ◽  
American Black Bears

Milk composition and intake, cub growth, and mass loss of hibernating lactating and nonlactating American black bears (Ursus americanus) and grizzly bears (Ursus arctos horribilis) were investigated. Except for ash content, milk composition was similar between species. Lipid content varied only slightly throughout lactation, whereas carbohydrate content increased from 1 to 3% during hibernation before decreasing to less than 0.5% at the end of lactation. Protein and dry matter content increased from 6.6 ± 0.4 and 29.8 ± 3.9% during hibernation to 13.7 ± 1.1 and 34.4 ± 3.7% post hibernation, respectively. The ash content of black bear milk increased from 1% during hibernation to 2% after den emergence, but the ash content of grizzly bear milk (1.3 ± 0.1%) did not fluctuate. Mean milk intake and growth during hibernation were 185 ± 89 and 49 ± 9 g/day for black bear cubs and 353 ± 54 and 98 ± 22 g/day for grizzly bear cubs, respectively, which accounted for about 9% of the estimated yearly milk consumption by the cubs. Milk intake peaked during the summer at levels approximately 4 times higher than those occurring in the winter den. The mass lost by older, hibernating, nonlactating bears was proportional to their metabolic body mass and was almost exclusively lipid. The rate of mass loss by denning, lactating females relative to nonlactating bears was 45% higher for black bears and 95% higher for grizzly bears. The less costly black bear cub may be at an important competitive advantage when both species occupy nutritionally limited habitat.

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 Whitebark Pine (Pinus albicaulis) seeds as food for bears (Ursus spp.) in Banff National Park, Alberta

2015 ◽  
Vol 129 (1) ◽  
pp. 8 ◽  
Author(s):  
David Hamer ◽  
Ian Pengelly
Keyword(s):  
National Park ◽  
Basal Area ◽  
Black Bears ◽  
Habitat Characteristics ◽  
Grizzly Bears ◽  
Pinus Albicaulis ◽  
Whitebark Pine ◽  
Banff National Park ◽  
American Black ◽  
American Black Bears

The large, nutrient-rich seeds of Whitebark Pine (Pinus albicaulis Engelmann) are important food for bears (Ursus spp.) in Yellowstone National Park. In Banff National Park, studies have shown that American Black Bears (Ursus americanus) eat these seeds, but little additional information is available. We studied Whitebark Pine in Banff National Park to address this information gap. Because bears obtain Whitebark Pine seeds from Red Squirrel (Tamiasciurus hudsonicus) middens, our objective was to measure the abundance, habitat characteristics, and use by bears of middens in Whitebark Pine forests. A second objective was to determine whether Grizzly Bears (U. arctos) in Banff National Park also eat Whitebark Pine seeds. In 2011–2012, we ran 29 ha of 20–50 m wide transects at 10 sites with accessible Whitebark Pine stands and found 0–3.7 middens/ha (mean 1.23, SD 1.17, n = 10). Midden density was weakly related to total basal area of all conifers but not to basal area of Whitebark Pine. Middens were located in the upper subalpine at an average elevation of 2110 m (SD 90, n = 8) on 41–248° facing slopes with a mean steepness of 28° (SD 5, n = 8). Bears had excavated middens at all eight sites where we found middens; at the remaining two sites, middens did not occur within our transects. Overall, 24 (67%) of the 36 middens located in our transects had been dug by bears. In October 2013, we searched areas where three global positioning system (GPS)-collared Grizzly Bears had been located in late September 2013 and found five recently dug middens located less than 6 m from GPS fixes. These observations are, to our knowledge, the first conclusive evidence that grizzly Bears in Banff National Park eat Whitebark Pine seeds. Because Whitebark Pine occurs at high elevations on steep slopes where human use is low, this resource may be important in keeping bears in habitat where risk of human-caused mortality is lower. Our results may assist managers responsible for conservation of bears in Banff National Park, where both American Black Bears and Grizzly Bears are subject to high levels of human-caused mortality.

Spring diet of American black bears (Ursus americanus) in a moose (Alces alces) – woodland caribou (Rangifer tarandus caribou) system in northern Ontario, Canada

2021 ◽  
pp. 721-728
Author(s):  
A.A.D. McLaren ◽  
S.E. Jamieson ◽  
M. Bond ◽  
A.R. Rodgers ◽  
B.R. Patterson
Keyword(s):  
Rangifer Tarandus ◽  
Ursus Americanus ◽  
Alces Alces ◽  
Black Bear ◽  
Black Bears ◽  
Rangifer Tarandus Caribou ◽  
Woodland Caribou ◽  
Northern Ontario ◽  
American Black ◽  
American Black Bears

American black bears (Ursus americanus Pallas, 1780) are opportunistic foragers, and across most of their range in North America, their diet is predominantly vegetation with limited consumption of vertebrates and invertebrates. However, they are also predators of ungulates, especially neonates, with regional variation in the amount of predation pressure they exert. We used scat analysis to examine the diet of black bears during the calving season in a moose (Alces alces (Linnaeus, 1758)) – woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) system in the Boreal forest of northern Ontario, Canada. Bears consumed herbaceous plants (46.5%), fruits and (or) seeds (20.0%), moose (3.3% adults; 4.3% calves), American beaver (Castor canadensis Kuhl, 1820; 8.5%), and insects (mostly ants; 4.2%). Bears had the highest consumption of moose and beaver in early spring, before switching to a more vegetation-dominated diet. We did not detect evidence of caribou consumption. Based on our results, black bear consumption of moose, particularly neonates, may warrant further investigation.

scholarly journals Temporal variation in food habits of the American Black Bear (Ursus americanus) in the boreal forest of northern Ontario

2013 ◽  
Vol 127 (2) ◽  
pp. 118 ◽  
Author(s):  
Derrick A. Romain ◽  
Martyn E. Obbard ◽  
James L. Atkinson
Keyword(s):  
Temporal Variation ◽  
Food Habits ◽  
Ursus Americanus ◽  
Late Summer ◽  
Black Bear ◽  
Black Bears ◽  
Northern Ontario ◽  
American Black Bear ◽  
American Black ◽  
American Black Bears

We used scat analysis to investigate temporal variation in the food habits of American Black Bears (Ursus americanus) in the boreal forest of northern Ontario. Specifically, we examined whether there was a seasonal shift in foraging over three years (1990–1992) and which foods, if any, varied in occurrence among years. American Black Bears ate foods ranging from green vegetation in the spring to ants in mid-summer and berries and nuts in late summer and fall. Late summer berry forage, especially blueberries (Vaccinium spp.), varied greatly among years. American Black Bears in northern Ontario consumed a variety of foods opportunistically. Understanding how American Black Bears in northern Ontario exploit food resources and how these food items vary among years can provide insights into demographic processes and help wildlife managers better anticipate changes in the structure of the harvest of American Black Bears and in human–bear conflict levels. In northern Ontario, forest management practices that increase the availability of early successional species would be beneficial to American Black Bear populations.

Dietary adjustability of grizzly bears and American black bears in Yellowstone National Park

2012 ◽  
Vol 77 (2) ◽  
pp. 270-281 ◽  
Author(s):  
Jennifer K. Fortin ◽  
Charles C. Schwartz ◽  
Kerry A. Gunther ◽  
Justin E. Teisberg ◽  
Mark A. Haroldson ◽  
...  
Keyword(s):  
Yellowstone National Park ◽  
National Park ◽  
Black Bears ◽  
Grizzly Bears ◽  
American Black ◽  
American Black Bears

Black bear marking behaviour at rub trees during the breeding season in northern California

Behaviour ◽  
2015 ◽  
Vol 152 (7-8) ◽  
pp. 1097-1111 ◽  
Author(s):  
A. Preston Taylor ◽  
Maximilian L. Allen ◽  
Micaela S. Gunther
Keyword(s):  
Breeding Season ◽  
Black Bear ◽  
Black Bears ◽  
The Novel ◽  
Video Cameras ◽  
Frequent Use ◽  
American Black ◽  
Marking Behaviour ◽  
American Black Bears ◽  
Novel Behaviour

We studied the marking behaviour of American black bears (Ursus americanus) during the breeding season 2013. Six remote video cameras captured 529 trapping nights. We collected behaviour, sex, and age class of bears rubbing on trees. Marking events () were observed between 26 April and 27 July with a median of 12 June. The majority (96%) of marking events were performed diurnally. All bears we could accurately identify to sex were males () and 29 of 31 marking bears were adults. The most frequent use of contact with substrate was bipedal marking followed by pede marking, quadrupedal marking. Bears used their back, neck, head, and cheeks in nearly 90% of observations while scratching and biting occurred in less than a third of observations. We documented the novel behaviour ‘groin marking’. This study suggests rub trees are locations for chemical communication through a variety of marking techniques in forested environments.

Helminths of grizzly bears (Ursus arctos) and American black bears (Ursus americanus) in Alberta and British Columbia, Canada

2015 ◽  
Vol 93 (10) ◽  
pp. 765-772 ◽  
Author(s):  
S. Catalano ◽  
M. Lejeune ◽  
P. Tizzani ◽  
G.G. Verocai ◽  
H. Schwantje ◽  
...  
Keyword(s):  
British Columbia ◽  
Ursus Arctos ◽  
Ursus Americanus ◽  
Statistical Significance ◽  
Black Bears ◽  
Grizzly Bears ◽  
Infection Prevalence ◽  
Infection Parameters ◽  
American Black ◽  
American Black Bears

Between May 2011 and June 2013, we collected the carcasses and gastrointestinal tracts of 40 American black bears (Ursus americanus Pallas, 1780) and 13 grizzly bears (Ursus arctos L., 1758) from populations of Alberta and British Columbia, Canada. Specimens were examined for helminths, which were identified to the species level by applying an integrated morphological and molecular approach. Our goal was to investigate parasite biodiversity and infection parameters in the sampled grizzly and black bears. We found seven parasite taxa: Dirofilaria ursi Yamaguti, 1941, Baylisascaris transfuga (Rudolphi, 1819), Uncinaria rauschi Olsen, 1968, Uncinaria yukonensis (Wolfgang, 1956), Taenia arctos Haukisalmi, Lavikainen, Laaksonen and Meri, 2011, Diphyllobothrium dendriticum (Nitzsch, 1824), and Diphyllobothrium nihonkaiense Yamane, Kamo, Bylund and Wikgren, 1986. The statistical significance of infection prevalence, intensity, and abundance for each helminth species was assessed relative to host species, gender, age class, sampling season, and location. This is the first unequivocal report of the potentially zoonotic tapeworms D. dendriticum and D. nihonkaiense in North American bears. Furthermore, we provide insight into the biology and ecology of the nematodes B. transfuga, D. ursi, and species of Uncinaria Frölich, 1789, and enrich the information available on the recently described tapeworm T. arctos.

“Dear, Honored Guest”

Bears ◽  
2020 ◽  
pp. 48-70
Author(s):  
David Mather
Keyword(s):  
Mixed Forest ◽  
Body Part ◽  
Black Bears ◽  
Grizzly Bears ◽  
Bone Fragments ◽  
American Black ◽  
American Black Bears ◽  
Culturally Connected ◽  
Calcined Bone ◽  
Indian Nations

Bears are represented in Minnesota’s archaeological record through rock art, effigy earthworks, and portable art, but most frequently through zooarchaeology. Most identified bone fragments are American black bears (Ursus americanus), with rare identifications of grizzly bears (U. arctos). These finds are found throughout the state, but are most frequent in the forested biomes of the Laurentian Mixed Forest and Eastern Broadleaf Forest. The sites are archaeological expressions of bear ceremonialism, culturally connected to the Dakota, Ojibwe, or related American Indian nations, and descriptions by native elders and cultural anthropologists Irving Hallowell and Ruth Landes. Analyses of body part representation and taphonomy (such as burned or calcined bone) allows interpretation of sites representing feasts or bear graves where the remains were respectfully placed. Traditions of bear ceremonialism in Minnesota also include cultural manifestations of bear power, such as by healers, warriors, spiritual societies, or clans.

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