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Myrmecophagy by Yellowstone grizzly bears

Canadian Journal of Zoology

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Abstract

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 12a??15A?C. Bears tended to select large ants (>8 mm long) nested in logs over small ants (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 4a??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.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Myrmecophagy by Yellowstone grizzly bears
Series title:
Canadian Journal of Zoology
Volume
79
Issue:
5
Year Published:
2001
Language:
English
Contributing office(s):
Forest and Rangeland Ecosystem Science Center
Description:
p. 779-793
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Canadian Journal of Zoology
First page:
779
Last page:
793
Number of Pages:
15