A real picture of those two acctually confronting? Wow! The polar bear, however, doesn't look much larger than the grizzly. However, denser bones could acctually make that polar bear heavier than it looks.
@ UM, it is important to to account for the distance from the photographer relative to the bears. The barren ground grizzly bear (visually, it looks to be a large or mature specimen) appears closer to the foreground. IMO, the polar bear is pushing or exceeding half a ton which is the normal weight average for a mature North American male polar bear. Having not seen the documentary, I am not 100% sure, but I will venture to guess the barren ground grizzly bear in the photo is also the same bear found in the Casey Anderson documentary photos on page one.
Post by Ursus arctos on Jul 12, 2012 15:45:53 GMT -9
In the documentary he said there were two brown bears visiting the carcass. It also contained the full clip. The grizzly left the carcass carrying a chunk of meet, and the polar bear followed looking mostly disinterested. The grizzly dropped the meet, turned, and threatened while advancing (pictured) until the polar bear turned to back off.
"Size and Weight. The polar bear is the largest of the extant bears (DeMaster and Stirling 1981). In Hudson Bay, the mean scale weight of 94 males >5 years of age was 489 kg. The largest bear in that group was a 13-year-old, which weighed 654 kg (Kolenosky et al. 1992). The heaviest bear we have weighed in Alaska was 610 kg, and several animals were heavy enough that we could not raise them with our helicopter or weighing tripod. Some animals too heavy to lift have been estimated to weigh 800 kg (DeMaster and Stirling 1981)."
Armstrup, C. Steven. 2003. Polar Bears (Chapter 27) in Wild Mammals of North America.
"When fully grown, adult male polar bears in Canada range in weight from 450-550 kg and most adult females weigh between 160-270 kg."
Stirling, Ian, Wendy Calvert, and Dennis Andriashek. 1980. Population ecology studies of the polar bear in the area of southeastern Baffin Island. [Ottawa]: Canadian Wildlife Service.
Ursus, did the documentary provide any information about the bears themselves, how old they were etc?
I remember a scene where a massive looking polar bear was mentioned to be a huge male, and believe a few others were said to be large. I think one of the two brown bears (the one in the picture) was also called large.
No specific details on age (that I recall). Largely generalisations. The researcher present (who set up barbed wire fences to collect fur samples) didn't present any life history details on individuals (and perhaps wasn't familiar with them).
Foraging ecology and coexistence of Asiatic black bears and sun bears in a seasonal tropical forest in Southeast Asia
Robert Steinmetz *, David L. Garshelis , Wanlop Chutipong , and Naret Seuaturien
Asiatic black bears (Ursus thibetanus) and sun bears (Helarctos malayanus) are ecologically similar and coexist extensively across Southeast Asia. We used foraging signs identified to bear species to examine their food selection and dietary overlap relative to food abundance, nutrition, and phenology in 3 habitats in Thailand. We posited, based on ecological theory, that coexistence of these 2 species would be explained through resource partitioning; our data, however, did not support this hypothesis. We conducted 71 sign transects and recorded 730 bear signs, mainly claw marks on trees that bears climbed for food. Both species fed predominantly on fruit; we documented 93 plant species from 42 families that bears consumed. Insects were of secondary importance. Bears of the 2 species selected fruit trees of the same families and genera in each habitat, especially lipid-rich Lauraceae and Fagaceae, tracking fruiting phenology through time. Diet overlap was high, even during periods of diminished fruit availability. We propose a number of mechanisms that may have promoted coexistence of these 2 species. For example, sun bears consumed proportionately more insects than did black bears; insectivory may help sustain the smaller-sized sun bears in the face of competition over fruits with black bears. Also, competition over fruits was reduced by both species cropping a lower proportion of common fruit trees than rarer fruit trees, thereby leaving a potential surplus for the other species. Furthermore, food resources were generally abundant and available year-round: about half the trees in the forest were potential food trees for bears. Bear populations likely were depressed below carrying capacity by previous hunting; as they recover, more competition for resources and greater niche divergence could ensue.