Visitor Counter

hitwebcounter web counter
Visitors Since Blog Created in March 2010

Click Below to:

Add Blog to Favorites

Grizzly bears, black bears, wolves, coyotes, cougars/ mountain lions,bobcats, wolverines, lynx, foxes, fishers and martens are the suite of carnivores that originally inhabited North America after the Pleistocene extinctions. This site invites research, commentary, point/counterpoint on that suite of native animals (predator and prey) that inhabited The Americas circa 1500-at the initial point of European exploration and subsequent colonization. Landscape ecology, journal accounts of explorers and frontiersmen, genetic evaluations of museum animals, peer reviewed 20th and 21st century research on various aspects of our "Wild America" as well as subjective commentary from expert and layman alike. All of the above being revealed and discussed with the underlying goal of one day seeing our Continent rewilded.....Where big enough swaths of open space exist with connective corridors to other large forest, meadow, mountain, valley, prairie, desert and chaparral wildlands.....Thereby enabling all of our historic fauna, including man, to live in a sustainable and healthy environment. - Blogger Rick

Subscribe via email to get updates

Enter your email address:

Receive New Posting Alerts

(A Maximum of One Alert Per Day)

Monday, January 13, 2014

Many of us can remember our moms telling us that we "got cranky" when hungry...........Well, no different for any other living creature who goes too long without proper nourishment...............In the case of Grizzly Bears studied in British Columbia, hungry Bears become more hostile than those that are properly food sated................When Salmon populations are at low ebb, Grizzlies testosterone levels fall dramatically...........While Testosterone is usually associated with reproduction, it also “facilitates behavioural and physical traits necessary to win social conflicts in fitness-enhancing situations...........While Bears are not normally focused on humans for protein, they will attack us out of a sense that they must eat something to continue living.................Canadian Central Coast Salmon runs have trended downward over the past 60 years and Wildlife Officials are trying to determine how to set appropriate commercial fishing limits so that the available salmon in any given year can be shared by man and bear alike with the idea that a fed bear is a less likely to get into conflicts with us

Low salmon returns make for hormonal bears

Illustration Beth May / The Martlet
Illustration Beth May / The Martlet
VICTORIA (NUW) — A recent study has uncovered that coastal grizzly bears are more prone to hostile behaviour when salmon numbers are low.
The study, conducted by the University of Victoria, the University of Calgary and the Raincoast Conservation Foundation, traced stress hormones in bears’ fur during periods when the expected salmon run was lower than average. Less salmon means greater competition for food, and the higher competition means grizzly bears could be a greater risk.
The main hormone that experienced change during periods of greater competition was testosterone. Testosterone is mainly thought of as a reproductive hormone; however, according to the study, it also “facilitates behavioural and physical traits necessary to win social conflicts in fitness-enhancing situations.”
“Testosterone, which we often think of as a male sex hormone, is also affected by the social competitive environment,” said Heather Bryan, one of the researchers, in an email. The study found it higher in both male and female coastal bears, as compared to other bears. Bryan said this “suggests that coastal bears have to compete more heavily for access to important resources such as salmon.”
Another hormone tested in the coastal bears was cortisol. Cortisol is a hormone that helps with long-term stress, recovery from stress and coping with change. Although salmon has high amounts of glucocorticoids, a class of steroid hormones to which cortisol belongs, coastal bears did not have a higher amount of cortisol in their fur samples.
The fur samples were collected on a 5,000-square-kilometre grid consisting of 73 area cells. Each cell was seven square kilometres. In each cell, researchers erected a barbed wire enclosure with a 25-metre perimeter. Inside the enclosure, the researchers placed some fish oil. This is called non-reward bait. Although bears are hopelessly attracted to the scent, when they arrive and there is nothing to eat or defend. Within a few short moments, the bears leave the enclosure. When bears pass under the barbed wire, small tufts of hair are pulled loose, and from those samples the researchers were able to find the information they were looking for.
People are reminded time and time again that bears are not the kind of animal that would ever attack a human for sport or snack, but a starved bear can be dangerous. With loss of habitat and food, it could mean life or death for the bear. In November, two residents of Churchill, Man. were attacked by a starved polar bear on the way home from a party. Another man in Quebec barely survived a bear attack while on a wilderness excursion sometime in August. These occurrences aren’t common, but bears do attack out of a sense of necessity.
Salmon numbers are known to fluctuate. Pink, coho and Chinook salmon were plentiful this year along B.C.’s coasts, but this isn’t always the case. As Bryan points out, there “has been an overall downward trend in the last 60 years with several dramatically low returns in the last decade on the central coast.” And while interior bears live off of a diet of mainly plants, the study points out, “salmon allows bears to meet their energetic requirements more efficiently than a diet of plants alone.”
When asked what could be done to increase the numbers of salmon available to the coastal bears, Bryan said, “Setting appropriate commercial fisheries so that salmon are shared among people and wildlife is important, but one of the challenges is that the exact number varies over space and time. Currently, fisheries quotas are determined based only on the needs of people, and do not consider the needs of wildlife.”
There is a national strategy called the Wild Salmon Policy that recognizes there are other species besides humans that have needs for salmon, but Bryan says “there isn’t a lot of information on exactly how much salmon other species need, which makes it difficult to implement the strategy.”

No comments: