Bears are bigger killers than thought gruesome video footage reveals

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first_img Email Country * Afghanistan Aland Islands Albania Algeria Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Cote d’Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People’s Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People’s Democratic Republic Latvia Lebanon Lesotho Liberia Libyan Arab Jamahiriya Liechtenstein Lithuania Luxembourg Macao Macedonia, the former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Martinique Mauritania Mauritius Mayotte Mexico Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Norway Oman Pakistan Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Qatar Reunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Vietnam Virgin Islands, British Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe The scenes start out innocently enough, often with a springtime stroll through Alaska’s Nelchina River Basin. But without warning, things turn grim: tableaus of blood and gore, usually with an unlucky caribou calf at the center.Such is the video footage collected by scientists over 3 years from cameras strapped around bears’ necks, offering the first “bear’s eye view” of life in this bucolic but harsh reserve. One of the team’s main findings: These bears kill a lot more than we think they do. A whole lot more.“It was really exciting because it’s the kind of thing you know occurs,” says Christopher Brockman, a wildlife biologist with the Alaska Department of Fish and Game (ADFG) in Palmer and lead author of the study. By carefully analyzing the most gruesome footage, the researchers were also able to identify the bears’ prey. More than half of their meals came from moose or caribou calves, whereas vegetation made up nearly 20%, and adult moose made up just over 12%, they report this month in the Wildlife Society Bulletin. But there were also some unusual items on the menu: snowshoe hares, swans, and even other brown bears. In one case, a 10-year-old male killed—and ate—a 6-year-old female bear.Overall, the bears killed an average of 34.4 moose and caribou calves over 45 days. That’s far higher than average kill rates from previous studies using other methods, including aerial observation. Compared with one 1988 study in which scientists counted an average of 5.4 moose calf kills from the air in a different part of Alaska, the new study found an average of 13.3 moose calf kills. The new study also found wide variation in the number of calves killed by any one bear, with one killing 44 calves in 25 days and another killing just seven in 27 days.That matters because kill rates are often used to manage wildlife living in protected areas. For example, if too many calves are being killed by bears, then removing a few of the predators could have a big impact on allowing the moose and caribou population to increase. Alternatively, Brockman says if the management goal is to increase bear numbers in an area, it may be important to pay attention to whether there are enough calves around in the spring to support more of the predators.Still, the study has its weaknesses. The low numbers make it hard to draw any firm conclusions about predation rates, says Martin Leclerc, a Ph.D. student at the Université de Sherbrooke in Canada who has studied how female brown bears use human settlements to shield their cubs. He also points out that the bears chosen in the first year of the study were known calf killers and could thus represent a bias in the overall numbers.But the use of camera collars could greatly improve knowledge about population dynamics in the future, Leclerc says. “The technological development will really help biologists and ecologists to have a more precise understanding of predator-prey relationships.” The behavior of an average brown bear Although researchers found that bears ate a lot more caribou and moose calves than was previously believed, a bear’s life is generally not particularly strenuous. Researchers tracking brown bears in Alaska’s Nelchina River Basin by GPS and collar cameras found that the animals only spent 6.2% of their time feeding, on average—most of their time is spent resting. Bears are bigger killers than thought, gruesome video footage reveals Click to view the privacy policy. Required fields are indicated by an asterisk (*) Sign up for our daily newsletter Get more great content like this delivered right to you! Country Figuring out the “kill rate” of large carnivores is notoriously difficult, says study author Bruce Dale, a wildlife science coordinator at ADFG in Palmer. It’s hard tracking them for long periods over large distances, and it’s also easy to miss a kill. A brown bear might spend a couple days eating an adult moose, compared with just 40 minutes for a caribou calf. So preferred tracking methods—like twice-daily aerial observations—can’t capture the full scope of bears’ hunting and feeding habits. They also can’t capture individual variation in kill rates, resulting in wildly different estimates for entire populations.To come up with a more accurate estimate, Brockman and his colleagues decided to try something new: outfitting the bears with camera collars and GPS trackers. Similar to security cameras, the collars filmed 10-second clips every 5 to 15 minutes for more than a month, from mid-May to late June. “We were focusing on the period of time when the [moose and caribou] calves are most vulnerable to predation,” Brockman says. He and his team collared 17 bears in total from 2011–13.Just seven collars provided the researchers with decent data—the others either fell off, didn’t work properly, or were chewed off their mothers by meddlesome bear cubs. But the ones that did work gave the team more than 100 hours of footage—36,376 clips in total. From those, the scientists reconstructed the bears’ days. Most of their time was spent resting or traveling (60.5% and 21.3%, respectively), and just 6.3% was spent feeding. There were even a few instances of bear mating caught on camera, Brockman says. G. Grullón/Science By Joshua Rapp LearnMar. 17, 2017 , 3:00 AMlast_img

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