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| Brown Bear - Ursus arctos | |
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| Tweet Topic Started: Jan 7 2012, 08:00 PM (28,282 Views) | |
| Mammuthus | Jan 1 2017, 08:53 AM Post #91 |
Proboscidean Enthusiast
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Brown Bears during the Pleistocene  This is a chunk of a Pleistocene Brown Bear cranial fragment.  Here are where Pleistocene Brown Bears fossils have been found. One was found in Ontario which was a skull which was dated 11 700 Bp, another Brown Bear fossil was found in Woodbridge which was a Brown Bear Humerus, the 3rd one was found in Trou Otis which was a Brown Bear skull. The last one was Gosselin San-pit (Saint Nicolas)  Here is the third metatarsal bone of 3 Bears, far left is a Black Bear, middle is a Pleistocene Brown Bear, and far right is a modern Brown Bear. Notice there is rough patches of arthritic bone on the Pleistocene Brown Bear. Edited by Mammuthus, Jan 1 2017, 08:55 AM.
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| Ceratodromeus | Mar 20 2017, 08:49 AM Post #92 |
Aspiring herpetologist
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Bears are bigger killers than thought, gruesome video footage reveals "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. 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. The behavior of an average brown bear lthough 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.  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.” " http://www.sciencemag.org/news/2017/03/bears-are-bigger-killers-thought-gruesome-video-footage-reveals Determining kill rates of ungulate calves by brown bears using neck-mounted cameras Abstract Predation of moose (Alces alces) and caribou (Rangifer tarandas) calves by brown bears (Ursus arctos) has been extensively studied, because predation has population implications for both predator and prey species. Existing methods have provided estimates of population-level predation rates, but they have not been able to estimate kill rates by individual bears until recently and the accuracy of these estimates was unknown. Our objectives were to evaluate whether collars equipped with video cameras would be able to record predation events by brown bears and provide useful estimates of ungulate kill rates. We fitted 17 brown bears in the Nelchina Basin of Alaska, USA, with Global Positioning System (GPS) collars equipped with cameras in the spring of 2011, 2012, and 2013. We retrieved the collars in late June of each year to download the video data and associated GPS locations. To compensate for incomplete sampling, we constructed a calf risk model from previous calf mortality studies and used it to predict total calf kills for each bear through the end of June. The camera collars documented kill rates considerably greater than previous estimates. Median handling times by bears were 40 min for caribou calves and 60 min for moose calves. These short handling times should be considered by future researchers when trying to evaluate kill detectability and when factoring calf mortality into population models. We demonstrate that this technology can be successfully applied in the field and provide recommendations on the video sampling intervals necessary to detect predation rates. http://onlinelibrary.wiley.com/doi/10.1002/wsb.733/abstract?campaign=wolearlyview |
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| zergthe | Mar 25 2017, 01:53 AM Post #93 |
Kleptoparasite
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Does anyone have information on wariness towards possible threats to its safety, i.e other bears, certain felids or large ungulates when not actively hunting or foraging? |
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| Warsaw2014 | Jul 19 2017, 05:21 AM Post #94 |
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Herbivore
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"...Obtaining weights of large bears is difficult. Relatively few large Kodiak males have been captured for research projects and even then the equipment needs and difficult terrain made weighing impractical. However, I gathered information from bear guides and Kodiak NWR files for hunter-killed bears that were cut into manageable portions and weighed with hand scales. I obtained weights for 21 males. Because I was only interested in large bears, I limited the sample to males weighing more than 800 lbs in spring and 1000 lbs in fall. For each bear I added 25 lbs to account for blood and other fluids lost in the weighing process. Bears reach maximum size in fall just prior to the winter denning period. Weights of three males taken in fall hunts averaged 1277 lbs (1078-1407 range). Eleven males taken in spring hunts averaged 937 lbs (803-1215 range). Because bear weights increase at least 25% from spring to fall, I adjusted the spring weights accordingly to estimate what those bears would have weighed the previous fall. The estimated fall weights ranged from 1004 to 1519 lbs and averaged 1171. The three largest weight estimates were 1245, 1483 and 1519 lbs. It’s interesting to note that an exceptionally large female taken on a fall hunt weighed 767 lbs. In most cases, the weights reported above were obtained because the guides and biologists recognized that the bears were unusually large. Thus, they probably represent the upper limits of male weights in spring and fall. The results indicate that the biggest Kodiak bears can grow to just over 1500 lbs. I extend thanks to bear guides Joe Want and Dick Rohrer, who provided most of the above information ..." http://www.kodiakbrownbeartrust.org/media/KBBT%202013%20Annual%20Report.pdf |
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| Warsaw2014 | Jul 22 2017, 04:45 PM Post #95 |
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Herbivore
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"...One tranquilized male on the Alaska Peninsula weighed 1,275 pounds in the spring..." https://www.nps.gov/glba/learn/nature/upload/Harmony-20with-20Bears.pdf "Because bear weights increase at least 25% from spring to fall, I adjusted the spring weights accordingly to estimate what those bears would have weighed the previous fall. " The estimated fall weight =1593,75 lbs ≈ 723 kg |
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| Taipan | Aug 24 2017, 05:13 PM Post #96 |
Administrator
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Climate change is luring Kodiak bears away from their iconic salmon streams Date: August 23, 2017 Source: Oregon State University  A female bear and her cubs on Kodiak Island, Alaska. Credit: Lisa Hupp, U.S. Fish and Wildlife Service Kodiak brown bears are abandoning salmon-their iconic prey-due to climate change, according to a new study. The bears are more interested in chowing down on early-arriving red elderberries. The likely result of this "prey switch," the researchers conclude, is a disrupted ecosystem on Alaska's Kodiak Island. The research was conducted by biologists at Oregon State University, University of Montana's Flathead Lake Biological Station, and Kodiak National Wildlife Refuge. The findings were published this week in the journal Proceedings of the National Academy of Sciences. The bears-the largest in the world-typically gorge on sockeye salmon in the summer. But in 2014, researchers were surprised to see streams in the Kodiak National Wildlife Refuge full of salmon-with no bears in sight. The scene repeated itself the next year. "Prior to that summer, we found streams that were littered with thousands of shredded salmon carcasses," Will Deacy, a postdoctoral researcher in OSU's College of Agricultural Sciences and lead author on the study. "In 2014 and again in '15, we were stunned to find such a strikingly different scene. There were piles of rotting, intact carcasses that had died after spawning instead of being killed by bears." It turns out the bears were on the hillsides, feeding on abundant red elderberries, which typically ripen after salmon have finished spawning in streams. Wild fruit, chock full of carbohydrates, is typically an important part of a brown bear's diet, especially when the spawning salmon are gone. Until recently, the bears would eat fish for most of the summer and then move on to the berries, which typically ripen at the end of the salmon season and are available from late August into early September. Bears are generalists that consume dozens of different foods throughout the year, but sockeye salmon and red elderberries are key foods for them. The researchers found that due to warm spring temperatures on Kodiak, the berries were developing fruit weeks earlier, at the same time as the peak of the salmon migration; 2014 was one of the warmest years on the island since record-keeping began 60 years ago. Although there will continue to be considerable variation in Kodiak's climate, the warming trend is likely to continue. The research team analyzed the bears' scat to find direct evidence that the bears were consuming the berries and not the salmon. "An earlier berry crop shut down one of the most iconic predator-prey scenes in nature," said Jonny Armstrong, an ecologist at OSU and member of the research team. "As climate change reschedules ecosystems, species that were once separated in time are now getting a chance to interact -- in this case the berries, bears and salmon. This is going to have large impacts that are hard to predict." For example, birds that depend on bears pulling salmon out of the stream, could be seriously affected, he said. Other far-reaching effects may include changes in bear demographics due to the change in their diet, evolving salmon populations and impacts on plant pollinators. "It is a strange, indirect effect of climate change," Deacy said. "These bears eat dozens of different foods throughout the year but now two of them are overlapping. This is causing a disruption in the food web that could have profound implications for the ecology of the island." The abundance of salmon and berries on Kodiak Island are why there are so many bears there, and why they are so large, said Jack Stanford, director emeritus at the University of Montana's Flathead Lake Biological Station and one of the study's co-authors. "This overlap in their resources forces the bears to make a choice that could in the long run result in fewer bears and/or unexpected changes in ecosystem structure," Stanford said. Story Source: Oregon State University. "Climate change is luring Kodiak bears away from their iconic salmon streams." ScienceDaily. www.sciencedaily.com/releases/2017/08/170823121333.htm (accessed August 24, 2017). Journal Reference: William W. Deacy, Jonathan B. Armstrong, William B. Leacock, Charles T. Robbins, David D. Gustine, Eric J. Ward, Joy A. Erlenbach, Jack A. Stanford. Phenological synchronization disrupts trophic interactions between Kodiak brown bears and salmon. Proceedings of the National Academy of Sciences, 2017; 201705248 DOI: 10.1073/pnas.1705248114 Abstract Climate change is altering the seasonal timing of life cycle events in organisms across the planet, but the magnitude of change often varies among taxa [Thackeray SJ, et al. (2016) Nature 535:241–245]. This can cause the temporal relationships among species to change, altering the strength of interaction. A large body of work has explored what happens when coevolved species shift out of sync, but virtually no studies have documented the effects of climate-induced synchronization, which could remove temporal barriers between species and create novel interactions. We explored how a predator, the Kodiak brown bear (Ursus arctos middendorffi), responded to asymmetric phenological shifts between its primary trophic resources, sockeye salmon (Oncorhynchus nerka) and red elderberry (Sambucus racemosa). In years with anomalously high spring air temperatures, elderberry fruited several weeks earlier and became available during the period when salmon spawned in tributary streams. Bears departed salmon spawning streams, where they typically kill 25–75% of the salmon [Quinn TP, Cunningham CJ, Wirsing AJ (2016) Oecologia 183:415–429], to forage on berries on adjacent hillsides. This prey switching behavior attenuated an iconic predator–prey interaction and likely altered the many ecological functions that result from bears foraging on salmon [Helfield JM, Naiman RJ (2006) Ecosystems 9:167–180]. We document how climate-induced shifts in resource phenology can alter food webs through a mechanism other than trophic mismatch. The current emphasis on singular consumer-resource interactions fails to capture how climate-altered phenologies reschedule resource availability and alter how energy flows through ecosystems. http://www.pnas.org/content/early/2017/08/15/1705248114 |
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| Taipan | Aug 31 2017, 05:31 PM Post #97 |
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Administrator
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Do squirrels teach bears to cross the railroad? Grizzlies dig squirrel middens for grains Date: August 30, 2017 Source: Pensoft Publishers  This is a Grizzly bear excavating a squirrel midden where bear signs had been previously recorded during a survey of an area with high bear use. The photo was taken with a remote camera on hyperfire settings. Credit: Julia Put Grains have been reported to regularly trickle from hopper cars travelling via the railway located within the Canadian Banff and Yoho National Parks, attracting the local red squirrels. As a result, the rodents have grown used to foraging on the spilled seeds, which they collect in underground storage areas where they can be discovered and dug up by grizzly bears. Grain-conditioned bears may frequent the railway more often than usual, resulting in increased mortality by trains strikes. Furthermore, the dispersal, following caching and digestion of such seeds by both squirrels and bears, could lead to the spread and establishment of those agricultural plants in the area. The case is investigated and discussed by members of the University of Alberta's research team of Julia Elizabeth Put, Laurens Put and Dr. Colleen Cassady St. Clair. Their study is published in the open access journal Nature Conservation. It all began when members of the team found a grain-filled midden that was visited by a bear near where the same bear had bluff-charged Parks Canada employees. At the time, the researchers were investigating possible explanations for causes of grizzly bear mortality on the adjacent railway. Thus, an unexpected opportunity to document interactions between species and how those can lead to human-wildlife conflicts presented itself to the scientists. The three basic questions brought up by Julia and her team were whether spilled grain could increase the number of squirrels near the rail; if other middens contained grain; and if other bears accessed grain in middens. Eventually, their data provided a resounding 'yes' to all of them. In some mountain parks in North America, including Banff, grizzly bears are known to excavate squirrel middens to access whitebark pine seeds. The tree, however, is only found at high elevations far from the valley bottom where the railway is located. Nevertheless, this behaviour may easily translate to targeting other food items in middens, such as grain, speculate the researchers. Once a bear consumes grain from a squirrel midden, it could initiate or reinforce a tendency to seek grain on the rail, where it is generally less concentrated. Such conditioning of food rewards could lead to grizzly bears spending more time in the area around or on the rails, where they would be at risk of being struck by trains. "The only feasible mitigation for these effects is to reduce spillage from hopper cars via careful attention to loading and gate maintenance," conclude the authors. Story Source: Pensoft Publishers. "Do squirrels teach bears to cross the railroad? Grizzlies dig squirrel middens for grains." ScienceDaily. www.sciencedaily.com/releases/2017/08/170830103451.htm (accessed August 31, 2017). Journal Reference: Julia Elizabeth Put, Laurens Put, Colleen Cassady St. Clair. Caching behaviour by red squirrels may contribute to food conditioning of grizzly bears. Nature Conservation, 2017; 21: 1 DOI: 10.3897/natureconservation.21.12429 Abstract We describe an interspecific relationship wherein grizzly bears (Ursus arctos horribilis) appear to seek out and consume agricultural seeds concentrated in the middens of red squirrels (Tamiasciurus hudsonicus), which had collected and cached spilled grain from a railway. We studied this interaction by estimating squirrel density, midden density and contents, and bear activity along paired transects that were near (within 50 m) or far (200 m) from the railway. Relative to far ones, near transects had 2.4 times more squirrel sightings, but similar numbers of squirrel middens. Among 15 middens in which agricultural products were found, 14 were near the rail and 4 subsequently exhibited evidence of bear digging. Remote cameras confirmed the presence of squirrels on the rail and bears excavating middens. We speculate that obtaining grain from squirrel middens encourages bears to seek grain on the railway, potentially contributing to their rising risk of collisions with trains. https://natureconservation.pensoft.net/articles.php?id=12429 |
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| Warsaw2014 | Sep 4 2017, 01:34 AM Post #98 |
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Herbivore
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Conflicts between humans and bears Case study: Brown bear In the late 1960s, about 100,000 brown bears lived in Russia (Vereshchagin 1972). The number of bears is now 180,000. The bear population density in the European part of Russia is 0.4 per 10 km2 , and that in the Asiatic part is 0.09 per 10 km2 (Gubar 2011). Since 1950s, the idea advanced that brown bear is not a pest animal but a valuable hunting trophy. Since 1981, hunters have to buy a license to hunt bear. Fig. 6 reflects the dynamics of brown bear numbers in different parts of Russia. The professional hunting often leads to the extermination of bears. Hunters with well trained dogs easily find bears in a forest during summer. There are professionals to find bear dens for the sale. Sport hunting of bears is difficult without assistance of professional hunters. My analysis of the bear densities in 529 districts of European Russia gave the positive correlation with forestation (0.61, P < 0.01) and the negative correlation with human density (–0.35, P < 0.01). Although both forest cover and a human abundance are the main factors affecting the bear population density, forest cover is likely a stronger factor for the bear density. In fact, some highly wooded and densely human populated areas (e.g., Leningrad and Perm’ oblast’, Udmurt, and Bashkir Republics) have the numerous bear populations. In woods a man can notice bears in a short distance. In 13% cases humans noticed a bear from 10 m, in 56% from a distance of 50 m, in 20% from 100 m, and in 11 % from 150 m (Loskutov et al. 1993). Only forests provide shelters for bears in the plain European Russia. During 1990–2015, more than 300 cases of brown bear’s attacks on humans were recorded in Russia. Only six of them happened in the European part of Russia (Komi Republic. Fig. 7). The largest number of attacks on people of bears were observed on Kamchatka and in Krasnoyarsky Kray (Fig. 7). Encounters between humans and bears are common in Siberia and rare in the European part in spite of fourfold more bear density there. It proves that the Siberian bears are not shy (Zavatsky 1993; Baskin 1996). The European bears always give humans the way to hide in bushes or behind a tree. But in Central Siberia bears attack humans in 1.6% of chance encounters, and they demonstrate exploratory behavior in 15% of chance encounters (Zavatsky 1993). In Siberia bears often attack people especially in years when their basic food is poor (Ustinov 1987). In such years, the bear terror become an important problem for local inhabitants. Food capacity of the bear habitats in the European part of the range is much higher and stable. Another important feature of environmental differences is the sparse human population in Siberia. Probably, hunting controls fearfulness of bears. According to the official data, only 2.5% of all bears are shot in Siberia annually (Gubar 2007). In the European part hunters kill 3.6% of all bears annually. Hunting success in the European part correlates with total numbers of bears (r = 0.73) but in Siberia the correlation is weak (r = 0.38). In the Asian part of Russia, the majority of bears inhabit the sparsely populated, remote localities. The Siberian bears often attack men working away from villages (86% cases). Women and children become bear prey in settlements. Starvation forces bears arrive at villages, even break into the houses. Conflicts between humans and bears occur in cemeteries where people leave food on the graves of relatives (the Russian custom). Siberian bears are so brave, and they are not afraid to attack a group of people (37% cases of the fatal attacks). Discussions The Russian experience confirms the Reinmoser’s conclusion (Reinmoser et al. 2013) that sustainable wildlife management requires integrated intersectoral cooperation. In Russia, hunting management is the main factor of game species dynamics. In the turbulent times of wars and revolutions the crashes of hunting management led to decline of the species, up to their extermination. The bans of hunting restored game species slowly. Licensing of hunt produced results more quickly when it based on counts and modelling of population dynamics. By this way, some species (sable and brown bear) have reached the high productivity  Fig. 6. Brown bear dynamics in the different parts of Russia during 1965–2010 (Data source: Vereshchagin 1972; Priklonsky 1967; Kashentseva 1990; Borisov et al. 1992; Baskin 1996, 1998; Gubar 1996, 2000, 2007, 2011). Dotted line: Central European Russia, Dashed line: Europian Russia, Black line: Siberia and Far East.  Fig. 7. Numbers of bear attacks on humans in the Russian regions during 1990–2015 (Data sources: collection from Internet information). Numbers in each region denote the number of bear attacks. http://www.bioone.org/doi/pdf/10.3106/041.041.0402 Bear attacks in Russia increase as population explodes and climate goes haywire https://www.sott.net/article/303657-Bear-attacks-in-Russia-increase-as-population-explodes-and-climate-goes-haywire |
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| Taipan | Oct 24 2017, 12:03 PM Post #99 |
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Administrator
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Routes out of isolation for Yellowstone grizzlies Montana scientists project pathways to wider mating pools in the Northern Rockies, based on characteristic movements of male bears Date: October 23, 2017 Source: Ecological Society of America Summary: An interagency team of Montana and Wyoming biologists models possible routes to a reunion of the Yellowstone and Northern Continental bear populations through adventurous male immigrants. An influx of genetic diversity through breeding with outsiders could give the Yellowstone grizzly population greater resiliency to changing environmental conditions.  Chad Dickinson, a biological science technician with the Interagency Grizzly Bear Study Team, fits a Global Positioning System collar on a male grizzly bear in Yellowstone National Park. Christopher Peck and colleagues used GPS telemetry data from males like this one to predict the behavior and habitat selection of bears exploring landscapes outside the Greater Yellowstone Ecosystem, on journeys that could bring them into contact with breeding grizzly populations in the Northern Continental Divide Ecosystem, and vice versa. They report their results in "Potential paths for male-mediated gene flow to and from an isolated grizzly bear population" in the journal Ecosphere. Credit: Frank van Manen In summer of 2017, biologists from Montana Fish, Wildlife and Parks confirmed sightings of a grizzly bear in the Big Belt Mountains northeast of Helena, Montana. The bear, an adventurous vanguard from its home range in the Northern Continental Divide Ecosystem of northwestern Montana, could be an unwitting pioneer on a path that may one day bring grizzlies from the Northern Continental Divide face to face with cousins long isolated in Yellowstone, say an interagency team of Montana and Wyoming biologists. They report their results in an article to be published next week in the Ecological Society of America's open access journal Ecosphere. Drawing from rich data on the movements of male bears in both grizzly populations, the researchers projected the rambles that future bears might take to pass through (or bypass) human occupied territory around Helena, Butte, and Bozeman, hopping between islands of wildlands in developed farm and rangeland. The bears' best options may be the longest routes, the researchers say, traversing state and federally owned wildlands in a westward arc around the more developed Interstate 90 corridor. "We let the male bears tell us where they would be most likely to go, by looking at their movement characteristics. We had the luxury of huge datasets of location data from both populations. We could be very picky about our data selection," said Frank van Manen, team leader for the Interagency Grizzly Bear Study Team. He coauthored the study with seven colleagues from Montana Fish, Wildlife and Parks, Wyoming Game and Fish, and his own home agency, the U.S. Geological Survey (USGS). Increasing public interest in a reunion of the Yellowstone and Northern Continental bear families motivated van Manen and colleagues to look at the possible paths the bears might take. An influx of genetic diversity through breeding with outsiders could give the Yellowstone grizzly population greater resiliency to changing environmental conditions. "We've been asked for this information by many groups invested in grizzlies. Organizations involved in land conservation want to know where land purchases will be most useful. Government agencies need to know where to put in place education efforts," said coauthor Cecily Costello, a research wildlife biologist at Montana Fish, Wildlife and Parks in Kalispell. "There were routes that were not obvious before we started, and a lot more alternatives than we thought initially," van Manen said. The predicted routes matched well with 21 verified sightings of grizzly bears outside their usual ranges, like the bear seen in the Big Belts this summer (number 19 on the accompanying map). Sightings extend back to 1998, but most occurred in the last two years. But trekking south towards Yellowstone through the Big Belts could be a relatively constrained and precarious route for bears, hemmed in by private land in low-lying valleys harboring highways, ranches, farms, and urban centers. Map visualizations of the models emphasize where corridors for the bears are narrowest. Overlapping predictions from the model indicate a tight squeeze for the bears, with few optimal paths. A scattered proliferation of paths through a region suggests that it offers more continuous habitat. "On the western edge there is more natural habitat, fewer humans. Paths are more diffuse, and longer, but those routes are much more secure. If bears were to go in those directions they would be much less vulnerable to mortality," van Manen said. But any crossing would likely take several years to complete, he said. Long term monitoring of the Yellowstone and Northern Continental grizzlies provided the researchers with a wealth of data on bear movements. They trained their model on data from 124 males carrying GPS transmitters, collected from 2000 to 2015 (199 bear-years), tracking how bears move, how far and how quickly they travel, the habitats and physical features they favor, and how they exploit and explore the landscape. Female bears typically set a home range near their mothers. The researchers looked only at the movements of male bears, which range more widely than females and are more likely to make the crossing of no-bears-land. "The sightings data validated the models. Also interesting, looking at the pattern of bear observations, is that most were likely from bears that originated in the Northern Continental Divide Ecosystem. Based on the data from both observations and modeling, it seems that an immigrant coming from the north is the more likely scenario, which is good, because that is what we want. That is what is needed," van Manen said. Establishing a natural genetic exchange between the populations, without resort to relocation of animals, is a top priority for many people invested in the recovery of grizzly bears, and a long-term management goal for the state of Montana. But expansion will take the bears onto private land, and lead to encounters with dangerous highways. With more human dominated landscapes comes the potential for conflicts with people. "The dispersing males, they are the ones that get in trouble, that get into the garbage, that roam into town, because they are more exploratory," van Manen said. Preparing people to coexist with bears may be as important as securing conservation easements, said van Manen and Costello. Bear-proof garbage storage systems and electric fences around beehives can minimize conflicts with people and go a long way towards securing a safe path for the bears. Costello would like to look at potential highway crossings, to investigate ways to mitigate collisions with vehicles. But she emphasizes that the models represent movement corridors. The projected paths, particularly where they cross more developed low country, do not necessarily indicate where bears would set up permanent residence. Grizzly bears generally prefer to be where people are not. Though they are adaptable to a wide variety of habitats and diets, they need a lot of undeveloped space. The domestication of the West during the twentieth century pushed grizzlies out of most of the lower 48 states, isolating a small population of bears in the haven of Yellowstone, the United States' first national park, and in the remote northwest corner of Montana. The Yellowstone bears were among the first animal populations protected by the Endangered Species Act, in 1975. They thrived under the act's protection, expanding from a group of perhaps fewer than 250 bears in the early 1980s to over 700 today, and spilling outside the park into adjacent federal forested lands. The grizzlies now roam over 65,000 square kilometers (25,000 square miles) of the Greater Yellowstone Ecosystem, with only about a fifth of the population inside the national park at its core. The U.S. Fish and Wildlife Service removed the Yellowstone grizzlies from threatened species protection under the Endangered Species Act in June, 2017. The bear population in the Northern Continental Divide, still listed as threatened, has grown on a similar trajectory. This group, which is about 1,000 bears strong, inhabits Glacier National Park and adjacent National Forests, connecting northward to grizzly populations in Canada. At the outermost edges of its range, only 110 kilometers (68 miles) separate it from the Yellowstone population. "110 kilometers is right on the cusp of what we might see in the dispersal patterns of males. We are within the realm of immigration events happening naturally," van Manen said. Story Source: Ecological Society of America. "Routes out of isolation for Yellowstone grizzlies: Montana scientists project pathways to wider mating pools in the Northern Rockies, based on characteristic movements of male bears." ScienceDaily. www.sciencedaily.com/releases/2017/10/171023101807.htm (accessed October 23, 2017). Journal Reference: Peck, C.P. et al. Potential paths for male-mediated gene flow to and from an isolated grizzly bear population. Ecosphere, 2017 DOI: 10.1002/ecs2.1969 Abstract For several decades, grizzly bear populations in the Greater Yellowstone Ecosystem (GYE) and the Northern Continental Divide Ecosystem (NCDE) have increased in numbers and range extent. The GYE population remains isolated and although effective population size has increased since the early 1980s, genetic connectivity between these populations remains a long-term management goal. With only ~110 km distance separating current estimates of occupied range for these populations, the potential for gene flow is likely greater now than it has been for many decades. We sought to delineate potential paths that would provide the opportunity for male-mediated gene flow between the two populations. We first developed step-selection functions to generate conductance layers using ecological, physical, and anthropogenic landscape features associated with non-stationary GPS locations of 124 male grizzly bears (199 bear-years). We then used a randomized shortest path (RSP) algorithm to estimate the average number of net passages for all grid cells in the study region, when moving from an origin to a destination node. Given habitat characteristics that were the basis for the conductance layer, movements follow certain grid cell sequences more than others and the resulting RSP values thus provide a measure of movement potential. Repeating this process for 100 pairs of random origin and destination nodes, we identified paths for three levels of random deviation (θ) from the least-cost path. We observed broad-scale concordance between model predictions for paths originating in the NCDE and those originating in the GYE for all three levels of movement exploration. Model predictions indicated that male grizzly bear movement between the ecosystems could involve a variety of routes, and verified observations of grizzly bears outside occupied range supported this finding. Where landscape features concentrated paths into corridors (e.g., because of anthropogenic influence), they typically followed neighboring mountain ranges, of which several could serve as pivotal stepping stones. The RSP layers provide detailed, spatially explicit information for land managers and organizations working with land owners to identify and prioritize conservation measures that maintain or enhance the integrity of potential areas conducive to male grizzly bear dispersal. http://onlinelibrary.wiley.com/doi/10.1002/ecs2.1969/abstract;jsessionid=EF4EC53D80B2A5E682C41A41CD6FF71C.f04t02 |
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| Warsaw2014 | Dec 8 2017, 02:15 AM Post #100 |
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https://translate.google.pl/translate?hl=pl&sl=pl&tl=en&u=gospodarkapodkarpacka.pl%2Fnews%2Fview%2F23091%2Fniedzwiedz-zabil-dwa-zubry-w-bieszczadach . . . . .    http://gospodarkapodkarpacka.pl/news/view/23091/niedzwiedz-zabil-dwa-zubry-w-bieszczadach Edited by Warsaw2014, Dec 8 2017, 02:17 AM.
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| Warsaw2014 | Dec 12 2017, 05:15 AM Post #101 |
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MINIMAL DISUSE MUSCLE ATROPHY AND SEASONAL ALTERATIONS IN THE CALCIUM HANDLING SYSTEM IN SKELETAL MUSCLE OF HIBERNATING BROWN BEARS By JOHN DAVIDSON HERSHEY http://www.dissertations.wsu.edu/dissertations/fall2008/j_hershey_020309.pdf "...Previous studies on wild black bears (Ursus americanus) have shown skeletal muscle morphology, composition and overall force generating capacity do not differ drastically between seasons despite prolonged inactivity during hibernation. The first goal of these studies was to compare the amount of muscle atrophy in captive brown bears (U. arctos) to that observed in wild black bears and measure seasonal differences in twitch characteristics. Samples from the biceps femoris muscle were collected during the summer and winter; protein concentration, fiber type composition and fiber cross-sectional area were measured along with twitch characteristics..." "...The study of the resistance to muscle atrophy in bears was pioneered by Dr. Henry J Harlow in wild black bears. Harlow et al. (2001) designed and implemented an apparatus which measured torque generated at the hock joint of a bear, in response to contraction of the hock flexors (primarily the cranial tibial and long digital extensor muscles). Utilizing percutaneous stimulation of the common peroneal nerve in sedated wild black bears, bears lost only 23% of strength in the hock flexors over a 130 day period (time period described as early and late winter), compared to a predicted loss of 90% in humans over the same time period and conditions. Additionally, the bears had no loss of skeletal muscle fiber size or number during the same time period. A more recent study on wild black bears using the same experimental apparatus determined that over a 110 day period, bears lost only 29% of muscle strength in the hock flexors, compared to human reports of a 54% decrease in the same muscle over a 90 day period of bed rest. Additionally, muscle contractile properties, including half-rise time, twitch contraction time and half-fall time remained unchanged (Lohuis et al. 2007). In a different study, the relative proportion of fast and slow fibers were quantified in the gastrocnemius of seven wild black bears and the biceps femoris of six wild black bears; samples were collected during the fall (October-November) and spring (March) (Rourke et al. 2006). .."   
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| Taipan | Dec 29 2017, 12:32 PM Post #102 |
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Iberian brown bears do not descend from those fled from the north during the Ice Age December 27, 2017, Plataforma SINC According to the glacier refuges theory, after the last glaciations, the bears of northern Europe sought shelter in the South. Researchers from A Coruña University reject this idea. They have reconstructed the colonization of brown bears in the Iberian Peninsula and shown that the lineage of the Pleistocene bears was lost. After the last glaciations in Western Europe, southern Europe could have been a refuge for some species of bears arrived from the North, according to a widely accepted scientific hypothesis. However, recent studies have added nuances to this idea. Now, a team of scientists from the A Coruña University has reconstructed the dynamics of the populations of bears in the Iberian Peninsula "We have investigated the mitochondrial DNA of a significant number of samples of current bears, from the Holocene the and Pleistocene, in the European context, and we have seen that the glacier refugee theory, commonly accepted, does not work for this species," explains Aurora Grandal Danglade, researcher of A Coruña University and co-author of the study published by the Historical Biology journal. In their work, they compiled data on the chronology and mitochondrial genome of brown bears (Ursus arctos) from Western Europe, adding new sequences of the current ones from the Cantábrico Mountains. "Through the study of today's bears, it had been seen that the brown bears of southern Scandinavia were of the same lineage as the current Iberian ones. This led to the hypothesis that the Peninsula would have served as a glacier refuge for the brown bears, which at the end of the last glacial maximum, would have colonized again Western Europe from here," explains Ana García Vázquez, co-author of the research. In the North of the Iberian peninsula there were three maternal lineages during the Pleistocene: one more numerous and two others of which only remains of a single individual of each group exist. The coexistence of three different lineages of bears is something that happens, for example, nowadays in Russia. However, on the Peninsula there is only one, which means that the other two lineages arrived from very distant areas and did not have continuity over time. This implies that the Pleistocene lineage was lost, and the Holocene bears, after the last glacial maximum, entered the peninsula from some unidentified area -probably France- and they did it 5,000 years after having colonized the British Isles. "It would be necessary to obtain more mitochondrial sequences from bears from other regions of Western Europe to clarify if the presence of these maternal lineages is casual or, on the contrary, no other representatives were found due to the scarcity of data," the scientist points out. The delay in the re-colonization of the Iberian Peninsula could be due to the orographical characteristics of the Pyrenees and the abundant presence of human beings in the natural entrance to the Peninsula. However, as there is no continuity of any of the Pleistocene lineages in the Holocene, Grandal and her team propose the existence of a cryptic refuge on the Atlantic slopes of continental Europe, ""from where the bears expanded as the ice receded," she concludes. https://phys.org/news/2017-12-iberian-brown-descend-fled-north.html Journal Reference: Ana García-Vázquez et al. Post-glacial colonization of Western Europe brown bears from a cryptic Atlantic refugium out of the Iberian Peninsula, Historical Biology (2017). DOI: 10.1080/08912963.2017.1384473 Abstract The European brown bear (Ursus arctos) shows a particular phylogeography that has been used to illustrate the model for contraction-expansion dynamics related to glacial refugia in Southern European peninsulas. Recent studies, however, have nuanced the once generally accepted paradigm, indicating the existence of cryptic refugia for some species further north. In this paper we collected available data on chronology and mitochondrial haplotypes from Western European brown bears, adding new sequences from present day individuals from the Cantabrian (North Iberia) area, in order to reconstruct the dynamics of the species in the region. Both genetics and chronology show that the Iberian Pleistocene lineages were not the direct ancestors of the Holocene ones, the latter entering the Peninsula belatedly (around 10,000 years BP) with respect to other areas such as the British Isles. We therefore propose the existence of a cryptic refugium in continental Atlantic Europe, from where the bears would expand as the ice receded. The delay in the recolonization of the Iberian Peninsula could be due to the orographic characteristics of the Pyrenean-Cantabrian region and to the abundant presence of humans in the natural entrance to the Peninsula. http://www.tandfonline.com/doi/full/10.1080/08912963.2017.1384473 |
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| Warsaw2014 | Jan 7 2018, 05:03 AM Post #103 |
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European brown bear (Ursus arctos) skeleton Edited by Warsaw2014, Jan 7 2018, 05:04 AM.
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| Taipan | Feb 28 2018, 05:33 PM Post #104 |
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Scientists use forensic technology to genetically document infanticide in brown bears Modern open-source software helped the researchers identify the male that killed a female and her two cubs Date: February 27, 2018 Source: Pensoft Publishers Scientists used a technology designed for the purposes of human forensics, to provide the first genetically documented case of infanticide in brown bears, following the murder of a female and her two cubs in Trentino, the Italian Alps, where a small re-introduced population has been genetically monitored for already 20 years. The study, conducted and authored by Francesca Davoli, The Italian Institute for Environmental Protection and Research (ISPRA), Bologna, and her team, is published in the open access journal Nature Conservation. To secure their own reproduction, males of some social mammalian species, such as lions and bears, exhibit infanticidal behaviour where they kill the offspring of their competitors, so that they can mate with the females which become fertile again soon after they lose their cubs. However, sometimes females are also killed while trying to protect their young, resulting in a survival threat to small populations and endangered species. "In isolated populations with a small number of reproductive adults, sexually selected infanticide can negatively impact the long-term conservation of the species, especially in the case where the female is killed while protecting her cubs," point out the researchers. "Taking this into account, the genetic identification of the perpetrators could give concrete indications for the management of small populations, for example, placing radio-collars on infanticidal males to track them," they add. "Nevertheless, genetic studies for identifying infanticidal males have received little attention." Thanks to a database containing the genotypes of all bears known to inhabit the study site and an open-source software used to analyse human forensic genetic profiles, the scientists were able to solve the case much like in a television crime series. Upon finding the three corpses, the researchers were certain that the animals had not been killed by a human. In the beginning, the suspects were all male brown bears reported from the area in 2015. Hoping to isolate the DNA of the perpetrator, the researchers collected three samples of hairs and swabbed the female's wounds in search for saliva. Dealing with a relatively small population, the scientists expected that the animals would share a genotype to an extent, meaning they needed plenty of samples. However, while the DNA retrieved from the saliva swabs did point to an adult male, at first glance it seemed that it belonged to the cubs' father. Later, the scientists puzzled out that the attacker must have injured the cubs and the mother alternately, thus spreading blood containing the inherited genetic material from the father bear. Previous knowledge also excluded the father, since there are no known cases of male bears killing their offspring. In fact, they seem to distinguish their own younglings, even though they most likely recognise the mother. To successfully determine the attacker, the scientists had to use the very small amount of genetic material from the saliva swabs they managed to collect and conduct a highly sophisticated analysis, in order to obtain four genetic profiles largely overlapping with each other. Then, they compared them against each of the males reported from the area that year. Eventually, they narrowed down the options to an individual listed as M7. "The monitoring of litters is a fundamental tool for the management of bear populations: it has allowed the authors to genetically confirm the existence of cases of infanticide and in the future may facilitate the retrieval of information necessary to assess the impact of SSI on demographic trends," conclude the researchers. Story Source: Pensoft Publishers. "Scientists use forensic technology to genetically document infanticide in brown bears: Modern open-source software helped the researchers identify the male that killed a female and her two cubs." ScienceDaily. www.sciencedaily.com/releases/2018/02/180227090715.htm (accessed February 27, 2018). Journal Reference: Francesca Davoli, Mario Cozzo, Fabio Angeli, Claudio Groff, Ettore Randi. Infanticide in brown bear: a case-study in the Italian Alps – Genetic identification of perpetrator and implications in small populations. Nature Conservation, 2018; 25: 55 DOI: 10.3897/natureconservation.25.23776 Abstract Sexually Selected Infanticide (SSI) is thought of as a male reproductive strategy in social mammalian species, because females who lose cubs may quickly re-enter oestrus. SSI has rarely been documented in non-social mammals and, in brown bears, SSI has been studied mainly in an eco-ethological perspective. The authors examined the first genetically documented infanticide case which occurred in May 2015 in brown bears in Italy (Trentino, Central-Eastern Alps). The infanticide killed two cubs and their mother. Hair samples were collected from the corpses as well as saliva, through swabs on mother’s wounds, with the aim of identifying the genotype of the perpetrator. The samples were genotyped by PCR amplification of 15 autosomal microsatellite loci, following the protocol routinely used for individual bear identifications within the Interregional Action Plan for Brown Bear Conservation in the Central-Eastern Alps (PACOBACE). Reliable genotypes were obtained from the mother, cubs and putative perpetrator. The genotypes were matched with those populating the PACOBACE database and genealogies were reconstructed. Both mother and perpetrator genotypes were already present in the database. Kinship analyses confirmed mother-cubs relationships and identified the father of the cubs. In this study, for the first time, the authors used the open-source LRmix STUDIO software, designed to analyse human forensic genetic profiles, to solve a case in wildlife. Through LRmix STUDIO, those alleles that do not belong to the victims were isolated and, finally, the perpetrator was identified. This study presents a method that allows, through the application of different models, the genetic identification of the conspecific perpetrator with the highest probability. The identification of the infanticidal male is relevant for the better management and conservation of wild populations with small effective population size (Ne) and low population growth rate, especially in the case of recently established populations in human-dominated landscapes. This procedure will have predictably wide applications, supplying important data in the monitoring of small and isolated populations. |
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| Taipan | Mar 28 2018, 03:37 PM Post #105 |
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Hunting turns bear cubs into mama's boys (and girls) Date: March 27, 2018 Source: Norwegian University of Life Sciences Summary: Human hunting changes brown bear reproductive strategies, so that the cubs stay with their mother longer. As a result, the females have fewer offspring, but grow older. We live in the Antropocene -- where human impact extends to all corners of the globe. New research shows that this also applies to the relationship between mothers and cubs of the Scandinavian brown bear. Human hunting has changed the characteristics of mother bear's care and how often she has cubs. Stays with mother bear longer "Generally, the cubs have followed their mother for a year and a half," says Professor Jon Swenson from the Norwegian University of Life Sciences (NMBU). "Only rarely have we observed them to follow her for two and a half years." This has now changed. Today, more cubs stay with their mothers an additional year, as opposed to 15-20 years ago. "Man is now an evolutionary force in the lives of the bears," Swenson says. Bear monitoring The Scandinavian brown bear is one of the world's most monitored animal populations. Norwegian and Swedish researchers have followed them closely since 1984. "The Scandinavian brown bear project is one of the world's two longest research projects on bears," Swenson says, who has been attached to the project almost since its very beginning. "We have followed over five hundred bears, many from birth to death." The number of shot bears in Sweden has increased steadily during this time. In the period 2010-2014, Swedish hunters shot about 300 bears each year. Game-changer In the vast majority of countries that allow bear hunting, there is a ban on hunting family groups. "A single female in Sweden is four times more likely to be shot as one with a cub," Swenson says. As long as a female has cubs, she is safe. This hunting pressure has resulted in a change in the proportion of females that keep their cubs for 1.5 years in relation to those that keep them for 2.5 years. In the period from 2005 to 2015, the number of females keeping their cubs for an additional year has increased from 7% to 36%. The individuals themselves do not alter their strategies. They portray either one behavior or the other, and this trait seems fixed. "This basically means that we are shooting more of those females that only keep their cubs for a year." One compensates for the other The new female strategy involves both advantages and disadvantages. Females who keep the cubs longer live safer lives, but on the other hand, they reproduce less often. This reduces their total number of offspring throughout their lives. "In an evolutionary perspective, this would not be beneficial," Swenson comments. "The animals with the most offspring "win" nature's race." However, the researchers' results show that the increased life of the females largely counteracts the reduced birth rate. "This is especially true in areas of high hunting pressure. There the females that keep their cubs the extra year have the greatest advantage." Story Source: Norwegian University of Life Sciences. "Hunting turns bear cubs into mama's boys (and girls)." ScienceDaily. www.sciencedaily.com/releases/2018/03/180327110515.htm (accessed March 27, 2018). Journal Reference: Joanie Van de Walle, Gabriel Pigeon, Andreas Zedrosser, Jon E. Swenson, Fanie Pelletier. Hunting regulation favors slow life histories in a large carnivore. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-03506-3 Abstract As an important extrinsic source of mortality, harvest should select for fast reproduction and accelerated life histories. However, if vulnerability to harvest depends upon female reproductive status, patterns of selectivity could diverge and favor alternative reproductive behaviors. Here, using more than 20 years of detailed data on survival and reproduction in a hunted large carnivore population, we show that protecting females with dependent young, a widespread hunting regulation, provides a survival benefit to females providing longer maternal care. This survival gain compensates for the females’ reduced reproductive output, especially at high hunting pressure, where the fitness benefit of prolonged periods of maternal care outweighs that of shorter maternal care. Our study shows that hunting regulation can indirectly promote slower life histories by modulating the fitness benefit of maternal care tactics. We provide empirical evidence that harvest regulation can induce artificial selection on female life history traits and affect demographic processes.
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