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

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.

Download Full-text

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

Canadian Journal of Zoology ◽

10.1139/cjz-2020-0263 ◽

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.

Download Full-text

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

The Canadian Field-Naturalist ◽

10.22621/cfn.v127i2.1442 ◽

2013 ◽

Vol 127 (2) ◽

pp. 118 ◽

Cited By ~ 5

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.

Download Full-text

Individual identification via remote video verified by DNA analysis: a case study of the American black bear

Wildlife Research ◽

10.1071/wr18049 ◽

2019 ◽

Vol 46 (4) ◽

pp. 326

Author(s):

Alan B. Ramsey ◽

Michael A. Sawaya ◽

Lorinda S. Bullington ◽

Philip W. Ramsey

Keyword(s):

Habitat Use ◽

Dna Analysis ◽

Black Bear ◽

Black Bears ◽

Individual Identification ◽

Video Cameras ◽

American Black Bear ◽

Open Population ◽

Other Information ◽

American Black

Context Researchers and managers often use DNA analysis and remote photography to identify cryptic animals and estimate abundance. Remote video cameras are used less often but offer an increased ability to distinguish similar-looking individuals as well as to observe behavioural patterns that cannot be adequately captured with still photography. However, the use of this approach in species with minimally distinguishing marks has not been tested. Aims To determine the utility and accuracy of distinguishing characteristics of American black bears, Ursus americanus, observed on remote video for identifying individuals in an open population. Methods We compared individuals identified on video with individuals and their sex identified by DNA analysis of hairs collected from hair traps visited by the bears. Key results We found that remote video could be used to determine the number of male and female black bears sampled by the video cameras. Specifically, we matched 13 individual bear genotypes with 13 video identifications, one genotype for each individual. We correctly matched ~82% of video identifications with all 38 genotypes collected from hair traps. Conclusions We demonstrated that distinguishing characteristics of a cryptic animal in remote video can be used to accurately identify individuals. Remote video complements genetic analysis by providing information about habitat use and behaviour. Implications When remote video cameras can be used to identify individuals, a wealth of other information will subsequently be obtained. Multi-year video-based studies can show sex ratios, and relative physical condition; shed light on fine-scale habitat use, such as when and where animals feed and what they eat; and display social interactions and rare behaviours.

Download Full-text

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

Canadian Journal of Zoology ◽

10.1139/z95-262 ◽

1995 ◽

Vol 73 (12) ◽

pp. 2216-2222 ◽

Cited By ~ 99

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.

Download Full-text

Litter size and cub age influence weight gain and development in American black bears (Ursus americanus)

Journal of Mammalogy ◽

10.1093/jmammal/gyaa009 ◽

2020 ◽

Vol 101 (2) ◽

pp. 564-573

Author(s):

J Bernardo Mesa-Cruz ◽

Colleen Olfenbuttel ◽

Michael R Vaughan ◽

Jaime L Sajecki ◽

Marcella J Kelly

Keyword(s):

Food Consumption ◽

Litter Size ◽

Ursus Americanus ◽

Black Bear ◽

Developmental Differences ◽

Black Bears ◽

Deciduous Teeth ◽

Relative Growth Rates ◽

American Black ◽

American Black Bears

Abstract We assessed the effects of cub age, litter size, and sex, on body mass (BM), absolute and relative growth rates (AGR, RGR), opening of ears and eyes, and deciduous teeth eruption from 129 cubs of American black bears (Ursus americanus) born at Virginia Tech’s Black Bear Research Center. Specific ages, related to maternal food consumption, and litter size, best described BM, AGR, RGR, and ear and eye development. Overall, newborns weighed ~0.44 kg at birth and increased ~9-fold by ~14 weeks. Twins were greater in BM than single cubs and triplets. Single and triplet cubs had higher AGR and RGR than twins after mothers resumed food consumption post-hibernation. Newborns displayed RGR > 3.5% that decreased until den emergence (RGR < 3.5% after emergence). RGR differed among litter sizes, particularly after den emergence. Ear and eye opening occurred concurrently at ~44 days of age, while teeth erupted ~10 days later. Single cubs experienced delayed development of these organs compared to other litter sizes. Postnatal developmental differences between black bears and other carnivores likely stem from strategies allowing black bears to minimize energy expenditure during the gestational period when hibernating.

Download Full-text