Myrmecophagy by Yellowstone grizzly bears

2001 ◽  
Vol 79 (5) ◽  
pp. 779-793 ◽  
Author(s):  
David J Mattson
Keyword(s):  
Forest Canopy ◽  
Ursus Arctos ◽  
Woody Debris ◽  
Regional Climate ◽  
Large Diameter ◽  
Grizzly Bears ◽  
Optimal Conditions ◽  
Important Food ◽  
Ursus Arctos Horribilis ◽  
Open Forest

I used data collected during a study of radio-marked grizzly bears (Ursus arctos horribilis) in the Yellowstone region from 1977 to 1992 to investigate myrmecophagy by this population. Although generally not an important source of energy for the bears (averaging <5% of fecal volume at peak consumption), ants may have been an important source of protein during midsummer and were heavily consumed during some years. Myrmecophagy was most common annually when known high-quality foods were scarce, as well as during the warmest months of the study, when regional average temperatures exceeded 12–15°C. Bears tended to select large ants (>8 mm long) nested in logs over small ants ([Formula: see text]6 mm long) nested under stones. Optimal conditions for consumption of ants occurred on the warmest sites with ample substrate suitable for ant nests. For ants in mounds, this occurred at low elevations at non-forested sites. For ants in logs, this occurred at low elevations or on southerly aspects where there was abundant, large-diameter, well-decomposed woody debris under an open forest canopy. Grizzly bears selected moderately decomposed logs 4–5 dm in diameter at midpoint. Ants will likely become a more important food for Yellowstone's grizzly bears as currently important foods decline, owing to disease and warming of the regional climate.

Bear feeding activity at alpine insect aggregation sites in the Yellowstone ecosystem

1991 ◽  
Vol 69 (9) ◽  
pp. 2430-2435 ◽  
Author(s):  
David J. Mattson ◽  
Colin M. Gillin ◽  
Scott A. Benson ◽  
Richard R. Knight
Keyword(s):  
Food Source ◽  
Ursus Arctos ◽  
Feeding Activity ◽  
Grizzly Bears ◽  
National Forest ◽  
Important Food ◽  
High Quality ◽  
Ursus Arctos Horribilis ◽  
Adult Females ◽  
Important Food Source

Bears (Ursidae) were observed from fixed-wing aircraft on or near alpine talus in the Shoshone National Forest between 15 June and 15 September in 1981–1989. Bears fed on insect aggregations at 6 known and 12 suspected alpine talus sites, disproportionately more at elevations > 3350 m, on slopes > 30°, and on south- and west-facing aspects. While at these sites, bears almost exclusively ate invertebrates, typically army cutworm moths (Euxoa auxiliaris). Subadult grizzly bears (Ursus arctos horribilis) appeared to be underrepresented at the sites, and proportionate representation of adult females with young appeared to decrease between 15 June and 15 September. Overall, observations of bears at these sites increased between 1981 and 1989. We suggest that alpine insect aggregations are an important food source for bears in the Shoshone National Forest, especially in the absence of high-quality foraging alternatives in July and August of most years.

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.

scholarly journals Can offsetting the energetic cost of hibernation restore an active season phenotype in grizzly bears (Ursus arctos horribilis)?

2021 ◽  
Author(s):  
Heiko T. Jansen ◽  
Brandon Evans Hutzenbiler ◽  
Hannah R. Hapner ◽  
Madeline L. McPhee ◽  
Anthony M. Carnahan ◽  
...  
Keyword(s):  
Heart Rate ◽  
Insulin Sensitivity ◽  
Metabolic Rate ◽  
Ursus Arctos ◽  
Metabolic Effects ◽  
Energetic Cost ◽  
Grizzly Bears ◽  
Flux Analysis ◽  
Active Season ◽  
Ursus Arctos Horribilis

ABSTRACTHibernation is characterized by suppression of many physiological processes. To determine if this state is reversible in a non-food caching species, we fed hibernating grizzly bears (Ursus arctos horribilis) glucose for 10 days to replace 53% or 100% of the estimated minimum daily energetic cost of hibernation. Feeding caused serum concentrations of glycerol and ketones (ß-hydroxybutyrate) to return to active season levels irrespective of the amount of glucose fed. By contrast, free-fatty acids and indices of metabolic rate, such as general activity, heart rate, and strength of the daily heart rate rhythm and insulin sensitivity were restored to roughly 50% of active season levels. Body temperature was unaffected by feeding. To determine the contribution of adipose to these metabolic effects of glucose feeding we cultured bear adipocytes collected at the beginning and end of the feeding and performed metabolic flux analysis. We found a roughly 33% increase in energy metabolism after feeding. Moreover, basal metabolism before feeding was 40% lower in hibernation cells compared to fed cells or active cells cultured at 37°C, thereby confirming the temperature independence of metabolic rate. The partial suppression of circulating FFA with feeding likely explains the incomplete restoration of insulin sensitivity and other metabolic parameters in hibernating bears. Further suppression of metabolic function is likely an active process. Together, the results provide a highly controlled model to examine the relationship between nutrient availability and metabolism on the hibernation phenotype in bears.

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 Can offsetting the energetic cost of hibernation restore an active season phenotype in grizzly bears (Ursus arctos horribilis)?

2021 ◽  
Author(s):  
Heiko T. Jansen ◽  
Brandon Evans Hutzenbiler ◽  
Hannah R. Hapner ◽  
Madeline L. McPhee ◽  
Anthony M. Carnahan ◽  
...  
Keyword(s):  
Heart Rate ◽  
Insulin Sensitivity ◽  
Metabolic Rate ◽  
Ursus Arctos ◽  
Metabolic Effects ◽  
Energetic Cost ◽  
Grizzly Bears ◽  
Flux Analysis ◽  
Active Season ◽  
Ursus Arctos Horribilis

Hibernation is characterized by depression of many physiological processes. To determine if this state is reversible in a non-food caching species, we fed hibernating grizzly bears (Ursus arctos horribilis) dextrose for 10 days to replace 53% or 100% of the estimated minimum daily energetic cost of hibernation. Feeding caused serum concentrations of glycerol and ketones (ß-hydroxybutyrate) to return to active season levels irrespective of the amount of glucose fed. By contrast, free-fatty acids and indices of metabolic rate, such as general activity, heart rate, and strength of the daily heart rate rhythm and insulin sensitivity were restored to roughly 50% of active season levels. Body temperature was unaffected by feeding. To determine the contribution of adipose to the metabolic effects observed after glucose feeding, we cultured bear adipocytes collected at the beginning and end of the feeding and performed metabolic flux analysis. We found a roughly 33% increase in energy metabolism after feeding. Moreover, basal metabolism before feeding was 40% lower in hibernation cells compared to fed cells or active cells cultured at 37°C, thereby confirming the temperature independence of metabolic rate. The partial depression of circulating FFA with feeding likely explains the incomplete restoration of insulin sensitivity and other metabolic parameters in hibernating bears. Further depression of metabolic function is likely to be an active process. Together, the results provide a highly controlled model to examine the relationship between nutrient availability and metabolism on the hibernation phenotype in bears.

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