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| Brown Bear - Ursus arctos | |
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| Tweet Topic Started: Jan 7 2012, 08:00 PM (28,285 Views) | |
| UrsusHorribilis | May 28 2013, 03:28 PM Post #46 |
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Unicellular Organism
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Huh, fascinating. So I do have another question, tangentially related to the first. Members on this forum have posted a lot in Interspecific Conflict about the legendary strength of the swipe of a grizzly bear's paw. There's those old urban legends that circulate around about California grizzlies killing fighting bulls with single swipes. There's the stories about grizzly bears decapitating moose with paw swipes. Exactly how hard could a brown bear hit with it's forelimbs anyways? They're immensely strong animals, that's for certain, but how much of the stories about the swipe of a grizzly bear are true and how much are fabricated? |
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| Ursus arctos | May 28 2013, 05:22 PM Post #47 |
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Autotrophic Organism
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"A third instance involved a grizzly bear found in late September 1988 that had died within the month along the Southeast Arm of Yellowstone Lake. The carcass had not been scavenged and was necropsied at the Wyoming State Veterinary Laboratory.The necropsy report indicated that the animal was a young adult male weighing ca. 118 kg at death. The bear died from a blow de- livered by another bear to the back, over the posterior thoracic vertebrae, and also had a large bite wound on one thigh." From "Cannibalism and predation on black bears by grizzly bears in the Yellowstone Ecosystem", by Mattson et al. Journal of Mammalogy, Vol. 73, No. 2 (May, 1992), pp. 422-425. More info, helping to answer both of your questions, from the book Identifying sheep killed by bears by David E. Griffel, Joseph V. Basile, Intermountain Forest and Range Experiment Station (Ogden, Utah):     There was some info on ShaggyGod suggesting moose may be especially vulnerable to decapitation, but I would have to see a modern report to really believe something like that could happen to an animal so large and powerful. Based on muscle info from Garmbaryan, brown bears do not appear particularly well adapted to extending the shoulder joint (bending the shoulder so the limb moves toward the animal's rear). On the other hand, the crossed-flight phase of a brown bear's stride when running is relatively very long, and the extended flight practically non-existent. -Crossed flight is the airborn phase after the front legs pushed off the ground. "Crossed" because the front legs are still bent toward the back of the animal, and the hind legs are stretching forward in preparation for contact with the ground. -Extended flight is the airborn phase after the rear legs pushed off the ground. Extended, because the legs are stretched apart- hind legs backwards, after having pushed off the ground, and front legs stretched forward in preparation for touching the ground. My uncertainty is because these two facts appear to contradict each other: 1) Brown bears appear less well adapted to pushing themselves forward with their front legs, based on muscle info. 2) Based on analysis of how they run, their front legs appear especially important to propelling them forward. Maybe their hind legs are just especially badly adapted for running But that would have to primarily be because of skeletal proportions and muscle architecture, rather than the relative sizes of their hind limb muscles compared to one another. Also, regarding strength: -Brown bears are not particularly impressive for the maximum strength or power they can produce with their forelimbs. Their strengths and specialisations are elsewhere. Ask yourself this: what was it that allowed this bear cub to hold its own against a much larger and physically stronger child? Strength isn't everything. I can provide more details, clarifications, etc, if readers are interested. Just ask! EDIT: While I might not think brown bears are particularly well adapted to striking in terms of strength or power of the striking movements, it is worth pointing out that they have relatively heavy distal limb segments. Especially their large, plantigrade, paws. This can be important. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006738 Edited by Ursus arctos, May 29 2013, 12:53 PM.
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| Bandog | May 29 2013, 09:09 PM Post #48 |
Everything else is just a dog.
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Its interesting that the omnivorous bear still has such impressive predatory know-how. Very cool info. |
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| Ursus arctos | May 30 2013, 03:30 AM Post #49 |
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Autotrophic Organism
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Depending on population, terrestrial meat can make up well over half their diet. Also in that post, some info on the impact of brown bear predation on some prey species- brown bear predation can make up a very important percentage of herbivore mortalities. There are other populations that are far less predatory (I have posted plenty of info in this profile). Many are largely herbivorous. Presumably, these bears have much less predatory know how. While those that are regular predators of course have plenty of experience. There is presumably very high individual variance. |
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| Jinfengopteryx | May 30 2013, 05:03 AM Post #50 |
Aspiring paleontologist, science enthusiast and armchair speculative fiction/evolution writer
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Daily activity patterns of brown bears were monitored using radiotelemetry from 1993 to 2006, in the Sikhote-Alin Biosphere Reserve and adjacent areas. Outside of the denning period, bears were active for approximately 52% of the 24-hour period. Males were more active (64% of total time) than females (51%). Brown bears in the Sikhote-Alin are diurnal and crepuscular, but switch to a nocturnal pattern in areas of high anthropogenic influence. During the summer months, daily activity patterns were influenced by precipitation, cloud cover, and air temperature. http://link.springer.com/article/10.1134/S1067413613010104# |
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| Ursus arctos | Jun 7 2013, 03:20 PM Post #51 |
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Autotrophic Organism
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750-pound bear is captured in Montana GREAT FALLS, Mont. (AP) — State bear managers seeking to capture and collar female grizzly bears as part of a population count recently trapped a 7 foot, 6 inch male grizzly that weighed 750 pounds after a winter of hibernation. Mike Madel, bear management specialist with the state Department of Fish, Wildlife and Parks, said it took two scales and a hydraulic crane to weigh the 8-year-old bruin that had 3 1/2-inch claws and a neck circumference of 4 feet. "This bear was just a beautiful bear," Madel said. Madel said the big male with the bronze head, golden back and dark chocolate legs could weigh as much as 900 pounds by the fall. "This is really a large male," he said. In fact, it is the second-largest male grizzly ever recorded in the Northern Rockies Region, Madel said. Madel captured the bear he dubbed "Big Daddy," on May 24. He was trying to capture female grizzlies near Choteau to fit them with radio collars to track their movements and whether they have cubs. "We actually were trying to avoid males," Madel said. But he decided to put a radio collar on the bear to track its range. Madel said he didn't know the big bear even existed. "Here's a bear that's down on the Front, and he's accustomed to moving in and around human activity, and he's never caused a conflict before," Madel said. The average-sized male grizzly along the Rocky Mountain Front is 600 pounds, while females are around 300 to 325 pounds. Madel, who has been managing bears on the Front for 24 years, wonders if the bear he trapped this spring was sired by the largest male grizzly ever recorded in the Northern Rockies: an 8-foot, 800-plus pound bruin trapped in 2003 in the Blackleaf Wildlife Management Area northwest of Choteau. "This bear," he said, "looked very much like that bear." Madel collected hair from the 2003 bear, but an Idaho lab lost the samples, making it impossible to know if they're related. Madel said the younger bear captured this spring hasn't reached its full size. "He's got some growing to do," Madel said.  Image caption: Montana Park authorities recently captured the second-largest grizzly bear ever recorded. It was captured in the 10,000-square-mile Northern Continental Divide Ecosystem. Its claws, shown here, are 3 1/2 inches long. From here. |
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| Taipan | Jul 30 2013, 03:50 PM Post #52 |
Administrator
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Yellowstone wolves spur recovery of bears' berries By Simon Redfern Reporter, BBC News 29 July 2013 Last updated at 18:31 GMT  Wolves were re-introduced to the park in the 1990s in an effort to control elk numbers The return of wolves to Yellowstone National Park may be leading to an improvement in the diet of grizzly bears, a study suggests. When wolves were eradicated from Yellowstone in the early 20th Century, the elk population boomed, devastating berry-shrubs relied upon by bears. Details are published in the Journal of Animal Ecology. A team from Oregon and Washington links the reintroduction of predatory wolves with a fall in over-browsing by elk. There is a consequent recovery in the availability of late-summer berries, the favoured pre-hibernation food of the grizzly bear. The study indicates that the number of berries measured in bear droppings has doubled as elk numbers have decreased, following the wolves' return in the 1990s. The complex interactions of the Yellowstone ecosystem were revealed in data measured before and after the reintroduction of wolves. David Mattson, a US Geological Survey (USGS) wildlife biologist, commented previously on Yellowstone: "It's a complex system and grizzly bears are a kind of consummate connector of all of the species in that system." The study shows that berry shrubs have increased since elk populations declined, and as shrubs recover from over-browsing the fruit consumption of bears has increased. William Ripple, lead author, commented: "Wild fruit is typically an important part of grizzly bear diet, especially in late summer when they are trying to gain weight as rapidly as possible before winter hibernation". "Elk browsing reducing berry production is well known in Europe as well," said Atle Mysterud, an ecologist from the University of Oslo. "The study shows that new patches of berries have formed after the wolves were reintroduced. It is clear that berry production is very important for bears." But the reduction in elk may not be all good news. Yellowstone's northern elk population hit 19,000 in 1988, but last winter the herd was estimated to number just 3,900 animals.  Double-edged sword: the bears feed on berries in late summer... and elk in spring Elk calves are an important food source for grizzly bears in the spring and Arthur Middleton of Yale University suggests that the decline in elk may pose a threat to the grizzly bear rather than a benefit, since their other spring food source, cutthroat trout, is also in decline. "This is an interesting paper and it is important that we understand the consequences of wolf recovery", Dr Middleton added.  The berry bushes also produce flowers of value to pollinators like butterflies and hummingbirds "But wolf re-introduction is not the only change that has occurred in recent years in Yellowstone. Bears eat elk and bear numbers have increased three or four times during this period. Bears eat about three times as many elk calves as wolves do and it may be that reduction in elk numbers and the increase in berry eating is feature of the increase in bear numbers. "Unfortunately, as wildlife ecologists working in a vast landscape such as the greater Yellowstone ecosystem it is very difficult to unravel the complexity of the patterns." The latest results demonstrate that acknowledging the many inter-relationships between species and environments in these systems is key to understanding that complexity. http://www.bbc.co.uk/news/science-environment-23495074 Journal Reference: William J. Ripple, Robert L. Beschta, Jennifer K. Fortin, Charles T. Robbins. Trophic cascades from wolves to grizzly bears in Yellowstone. Journal of Animal Ecology, 2013; DOI: 10.1111/1365-2656.12123 Summary We explored multiple linkages among gray wolves (Canis lupus), elk (Cervus elaphus), berry-producing shrubs, and grizzly bears (Ursus arctos) in Yellowstone National Park. We hypothesized competition between elk and grizzly bears whereby, in the absence of wolves, increases in elk numbers would increase browsing on berry-producing shrubs and decrease fruit availability to grizzly bears. After wolves were reintroduced and with a reduced elk population, we hypothesized there would be an increase in the establishment of berry-producing shrubs, such as serviceberry (Amelanchier alnifolia) which is a major berry-producing plant. We also hypothesized that the percent fruit in the grizzly bear diet would be greater after than before wolf reintroduction. We compared the frequency of fruit in grizzly bear scats to elk densities prior to wolf reintroduction during a time of increasing elk densities (1968-1987). For a period after wolf reintroduction, we calculated the percent fruit in grizzly bear scat by month based on scats collected in 2007–09 (n = 778 scats) and compared these results to a scat data collected before wolf reintroduction. Additionally, we developed an age structure for serviceberry showing the origination year of stems in a northern range study area. We found that over a 19-year period, the percent frequency of fruit in the grizzly diet (6,231 scats) was inversely correlated (p < 0.001) with elk population size. The average percent fruit in grizzly bear scats was higher after wolf reintroduction in July (0.3% versus 5.9%) and August (7.8% versus 14.6%) than before. All measured serviceberry stems accessible to ungulates originated since wolf reintroduction, while protected serviceberry growing in a nearby ungulate exclosure originated both before and after wolf reintroduction. Moreover, in recent years, browsing of serviceberry outside of the exclosure decreased while their heights increased. Overall, these results are consistent with a trophic cascade involving increased predation by wolves and other large carnivores on elk, a reduced and redistributed elk population, decreased herbivory, and increased production of plant-based foods that may aid threatened grizzly bears. http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12123/abstract Edited by Taipan, Oct 24 2017, 11:41 AM.
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| Taipan | Aug 24 2013, 06:09 PM Post #53 |
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Grizzly bear chows down on black bear near Canadian hiking trail Sarah WolfeGlobalPost.com August 23, 2013 Officials in Alberta's Banff National Park had to close the Sundance Canyon area earlier this month after a large male grizzly bear ate a black bear in the popular hiking area. The grizzly known as No. 122 was found feasting on the carcass by a group of hikers. An investigation later determined the carcass was of a small black bear. “It had been completely consumed,” Steve Michel, a human wildlife conflict specialist with Banff National Park, told the Calgary Herald. “There was nothing remaining other than a skull, a hide, the four paws and some bones.” It's believed to be a predatory attack on the black bear. Wildlife experts say the black bear was likely foraging along the trail and was just in the wrong place at the wrong time. The grizzly had about a big size advantage. "We know it's a dog-eat-dog world out there, but we're finding out it's a bear-eat-bear world as well," Michel joked to CBC News. http://www.alaskadispatch.com/article/20130823/grizzly-bear-chows-down-black-bear-near-canadian-hiking-trail |
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| Taipan | Mar 26 2014, 02:01 PM Post #54 |
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Study yields 'Genghis Khan' of brown bears, and brown and polar bear evolution Date: March 25, 2014 Source: Molecular Biology and Evolution (Oxford University Press) Summary: By mining the genome of a recently sequenced polar bear, researchers developed Y chromosome-specific markers, and analyzed several regions of the Y chromosome from a broad geographic sample of 130 brown and polar bears. 'This pattern in brown bears covers even larger geographic areas than analogous findings from humans, where the Y-chromosomal lineage of Genghis Khan, founder of the Mongol Empire, was spread across much of Asia,' said experts. Male bears are seemingly always on the prowl, roaming much greater distances than females, particularly for mating. For bear evolution, studying the paternally inherited Y chromosome is therefore a rich source to trace both the geographic dispersal and genetic differences between bear species. This new study is particularly important, because a large part of our current knowledge about range-wide population structuring in mammals relies on data from maternally inherited mitochondrial DNA (mtDNA). More extensive male than female movement in bears and many other mammals implies that males carry genetic material over greater geographic distances than females. Therefore, the pronounced population structuring that has been reported for female-inherited mtDNA genes in brown bears might not be representative of the species as a whole. By mining the genome of a recently sequenced polar bear, researchers from Axel Janke´s group at the Biodiversity and Climate Research Centre in Frankfurt, Germany, developed Y chromosome-specific markers, and analyzed several regions of the Y chromosome from a broad geographic sample of 130 brown and polar bears. They also included a continuous 390,000 base pair long stretch of genomic Y chromosomal region available in brown, polar and black bear genomes to gain a better understanding of the paternal signature of bear evolution. They found evidence of extensive male gene flow that has led to the distribution of some brown bear Y chromosomes across incredibly large geographic distances, with two brown bears as far away as Norway and the Alaskan ABC islands carrying very similar Y chromosomes. This implies that one male brown bear lineage has spread across most of the brown bear's distribution range. "This pattern in brown bears covers even larger geographic areas than analogous findings from humans, where the Y-chromosomal lineage of Genghis Khan, founder of the Mongol Empire, was spread across much of Asia," said Tobias Bidon and Frank Hailer, lead authors of the study. Because their data consistently showed that black, brown and polar bears carry highly distinct Y chromosome lineages, the researchers also estimated the timing of the split between the male lineages of brown and polar bears. The obtained time estimate for the speciation event of brown and polar bears is ca. 0.4 to 1.1 million years ago. This is significantly older than previous estimates based on mtDNA, confirming recent observations from autosomal markers that brown and polar bears from a genetic point of view represent highly distinct species. The study also shows that dispersing males connect the enigmatic brown bear population of the Alaskan ABC-islands to the North American mainland, and that the resulting movement of genes is substantial enough to maintain high genetic variability within this island population. The study demonstrates that the Y chromosome represents an understudied part of the mammalian genome, providing crucial information to our understanding of the geographic structuring and evolutionary history of species. http://www.sciencedaily.com/releases/2014/03/140325210631.htm Journal Reference: Tobias Bidon, Axel Janke, Steven R. Fain, Hans Geir Eiken, Snorre B. Hagen, Urmas Saarma, Björn M. Hallström, Nicolas Lecomte, and Frank Hailer. Brown and polar bear Y chromosomes reveal extensive male-biased gene flow within brother lineages. Mol Biol Evol, March 25, 2014 DOI: 10.1093/molbev/msu109 Abstract Brown and polar bears have become prominent examples in phylogeography, but previous phylogeographic studies relied largely on maternally inherited mitochondrial DNA (mtDNA) or were geographically restricted. The male-specific Y chromosome, a natural counterpart to mtDNA, has remained under-explored. Although this paternally inherited chromosome is indispensable for comprehensive analyses of phylogeographic patterns, technical difficulties and low variability have hampered its application in most mammals. We developed 13 novel Y-chromosomal sequence and microsatellite markers from the polar bear genome, and screened these in a broad geographic sample of 130 brown and polar bears. We also analyzed a 390 kb-long Y-chromosomal scaffold using sequencing data from published male ursine genomes. Y chromosome evidence support the emerging understanding that brown and polar bears started to diverge no later than the Middle Pleistocene. Contrary to mtDNA patterns, we found (i) brown and polar bears to be reciprocally monophyletic sister (or rather brother) lineages, without signals of introgression, (ii) male-biased gene flow across continents and on phylogeographic time scales, and (iii) male dispersal that links the Alaskan ABC-islands population to mainland brown bears. Due to female philopatry, mtDNA provides a highly structured estimate of population differentiation, while male-biased gene flow is a homogenizing force for nuclear genetic variation. Our findings highlight the importance of analyzing both maternally and paternally inherited loci for a comprehensive view of phylogeographic history, and that mtDNA-based phylogeographic studies of many mammals should be re-evaluated. Recent advances in sequencing technology render the analysis of Y chromosomal variation feasible, even in non-model organisms. http://mbe.oxfordjournals.org/content/early/2014/03/20/molbev.msu109 |
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| Vodmeister | Apr 8 2014, 04:00 AM Post #55 |
Ultimate Predator
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Here's data on the absolute largest subspecies of Brown Bears, those of Alaska Peninsula and Kodiak Island: Study on Kodiak Brown Bears;  835 pounds is an average for a sub-adult 8-9 year old Kodiak. Notice the section under Adult Weight. "Willard A. Troyer writes: Four males weighed in the fall ranged from 960 - 1,346 pounds and three spring species ranged from 813 - 1190 lbs." Take the median value between 813 and 1190, and you'll come up with an average of about 1000 lbs for boar Kodiak Brown Bears. ADF&G technical report on Alaskan Grizzlies suggests an average weight of 441 kg, or 974 lbs for mature (>10 y.o.) Brown Bears from Alaska Peninsula.  Coastal grizzlies;  Bear hunting in Alaska: the brown & grizzly bear hunter's guide - By Tony Russ Another study done by Bear Biology;  Data on brown bears of Alaska Peninsula (including youngsters); Size and Weight of Brown Bears of Alaska Peninsula during Spring Time Edited by Vodmeister, Jun 10 2014, 10:41 PM.
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| Vodmeister | Apr 8 2014, 04:02 AM Post #56 |
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Ultimate Predator
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Kamchatka Brown Bear "The bigger of the two was about 10 feet tall and weighed about 1,050 pounds. The smaller one stood 9 feet tall and weighed about 950 pounds."  15 March 2008 - By John Gunther theworldlink.com/sports/outdoors/bears-provide-fun-challenge-for-taxidermist/article_cc8f9f59-b7e4-5b0b-8334-0022fba96248.html#ixzz1mdG4FFDI Mean mass, 1000 lbs. Sample size, 2. "Size and mass of Kamchatka subtype of brown bear (U a. piscator of Pucheran, 1855) one of the largest ground-based bear predators and under optimal conditions the maximum fixed weight of a male of Kamchatka bear registers 600 kg, the average weight 350-450 kg are confirmed data and before the autumn period the weight of record specimens have exceeded 700 kg." (Gordienko, 2005). Mean mass 400 kg (882 lbs). Sample size, unknown. "The dimensions of this bear exceed the dimensions of usual brown. Its length frequently reaches 250 cm, with the height before the arms 140 cm. the weight of the old male before the bedding before the den frequently reaches 400 kg, but there are the cases of the acquisition of bears before 425 kg. Fat in this colossus sometimes can weigh up to 150 kg." (N.A. Baikov) Similar to Gordienko, Baikov also suggests a mean spring/summer mass 400 kg (882 lbs). The first source isn't really a study, so I'd take the other two as prime examples of evidence to support that Kamchatka Brown Bear average about 400 kg. Back in the 1940's;  Excessive hunting caused a sharp decline in the size of the animal. The bigger were weeded out, and the smaller were left to breed. Edited by Vodmeister, Jun 10 2014, 10:42 PM.
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| Vodmeister | Apr 8 2014, 04:04 AM Post #57 |
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Ultimate Predator
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Chinese hunting records The 275kg female brown bear and the 225kg male brown in the Northeast China. Sex\boby mass\HB length\Tail lenght\Hind foot length\Ear length  The 212kg female Tibetan brown bear and other about Tibetan brown bear. Sex\boby mass\HB length\Tail lenght\Hind foot length\Ear length  The 350kg female brown bear in the Northeast China according to hunter. 
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| Canadianwildlife | Apr 8 2014, 05:42 AM Post #58 |
Apex Predator
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So according to the results after weighing kodiak bears, some of the males weighed 1,190 lbs, so saying a kodiak bear at maturity is 1,000-1,200 lbs would be close enough and is correct. My bears of the world source and your charts agree after all. 1,000-1,200 lbs. 1,190 lbs is close enough to 1,200 lbs, so my source was correct, as it agree with your first rate chart source where the animals have actually been weighed in the wild. Edited by Canadianwildlife, Apr 10 2014, 12:48 PM.
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| Canadianwildlife | Apr 10 2014, 12:48 PM Post #59 |
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Apex Predator
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Interesting information. |
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| Vodmeister | Apr 10 2014, 01:16 PM Post #60 |
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Ultimate Predator
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Photobucket is glitching again. So many of my data screenshots have gone blank and it ruins my posts. |
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