Monthly Archives: May 2016

Bear Hibernation (Part Two)

Kodiak Bear, Kodiak Wildlife, , , , , , , ,

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Last week I posted about the mechanics of bear hibernation, but how does a large mammal manage to curl up in a ball in a cave and sleep for five months? Humans and other mammals would die if they tried to hibernate. During hibernation, bears do not eat, urinate or defecate. What physiological adaptations allow them to do this?

While in hibernation, a brown bear’s breathing drops from 6 to 10 breaths per minute to one breath every 45 seconds. His heart rate drops from forty to fifty beats per minute to nineteen beats per minute, but his body temperature decreases only a few degrees and does not drop below 88° F (31°C), which is within 12°F (6°C) of his normal body temperature. Some scientists consider bears to be “super hibernators.” Because they have thick fur and also a lower surface area to mass ratio than do smaller hibernators such as rodents, bears lose body heat slowly, which allows them to cut their metabolic rate by 50-60%. Physiologist Øivind Tøien at the University of Alaska Fairbanks has discovered that while a black bear’s body temperature only drops an average of 9.9° F (5.5° C), the bear’s metabolism plunges to 25% of the average summer rate. Furthermore, his studies indicate that when a black bear comes out of hibernation in the spring, it takes several weeks for the bear’s metabolism to return to normal.

The amazing physiological adaptations of bears during hibernation are of much interest to human medical researchers. If a human must endure prolonged bed rest due to paralysis or illness, if a broken limb is immobilized, or if an astronaut spends several months in space; the human body faces such risks as blood clots, heart failure, significant loss of muscle mass, a breakdown of carbohydrates, proteins, and fats, as well as life-threatening bedsores. A hibernating bear has none of these risks, including no loss of muscle function. Scientists are interested in determining what specific changes in metabolites, proteins, and hormones allow bears these physiological adaptations during several months of inactivity. Humans, as well as all other mammals who maintain non-weight-bearing positions for an extended period, suffer from osteoporosis, but bears do not lose bone mass during hibernation. When the secret to how bears accomplish this feat is discovered, it may help people with weak bones, patients who become bedridden for a prolonged period, people who suffer paralysis, and astronauts on long space missions.

While bears are hibernating and metabolizing body fat, their cholesterol levels are twice as high as respective cholesterol levels in humans. Bears, however, do not suffer from arteriosclerosis or gallstones, conditions which plague humans with high cholesterol. Furthermore, a bear’s liver secretes a substance that dissolves gallstones in humans. Insight into how bears recycle urea during hibernation could lead to advances in treatments for kidney failure and dialysis in humans. Also, bears gain a great deal of weight in the fall before going into hibernation, but unlike many obese humans, they remain insulin-sensitive. Conversely, they become insulin-resistant once they are in hibernation, so their fat does not break down too quickly, but when they wake in the spring, they once again respond to insulin. In other words, bears can put themselves into a diabetic state while in hibernation and then reverse out of it in the spring. Understanding what allows bears to do this could lead to breakthrough medical advances in the treatment of diabetes and obesity in humans.

There’s so much more going on with hibernation than simply curling up for a long winter’s nap. I look forward to reading new scientific studies on bear hibernation.

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Kodiak Bear Hibernation (Part One)

Kodiak Bear, Kodiak Wildlife, , , , , , , ,

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Hibernation is one of the most amazing physiological adaptations in nature, and the more I learn about bear hibernation, the more the process fascinates me. Most bears have recently left their dens here on Kodiak, and they are slowly restarting their digestive systems as they prepare for the summer feeding season. Over the next two weeks, I’ll post about denning and hibernation for Kodiak bears. I wrote a post a year ago about den emergence on Kodiak, but this time, I will discuss hibernation in more detail.

Bears hibernate in the winter to conserve energy when weather conditions are harsh, and food is scarce. While hibernating bears experience a degree of dormancy, it is nowhere near as extreme as it is in many other species such as bats, squirrels, and rodents. On Kodiak where winters are relatively mild, bears often go into and out of hibernation and some bears (mostly boars) do not hibernate at all. It is common to see bear tracks in the snow all winter on Kodiak.

Bears typically enter their dens in the order of pregnant females followed by lone females and then females with cubs. Males are the last to enter their dens, and large, old boars in particular may not hibernate at all. Denning conditions vary from year to year depending on the weather conditions and the availability of food.

The time of den emergence in the spring is also dependent upon temperature and weather conditions and varies by sex and age. Males typically leave their dens first, followed by single females and then sows with cubs. Sows with newborn cubs are the last to emerge   Males usually spend three to five months in hibernation while pregnant females may hibernate as long as seven months.

While there is an instinctual aspect to denning, it also appears to be a learned behavior that sows teach their cubs. Perhaps the most important information the mother bear relays to her cubs is how to choose a den site. On Kodiak, there are few natural rock caves, so bears must dig their dens into the sides of the mountains or the sides of snow banks. Lawrence Van Daele, Victor Barnes Jr., and Roger Smith studied and compared denning behaviors on the northern part of the island to those on southwestern Kodiak. On the northern portion of Kodiak where the mountains are taller, they determined that the bears in their study group denned at an average elevation of 2180 ft. (665m). The bears in this region preferred steep slopes in alpine habitat for their dens, probably because the dens were high enough that the soil remained frozen throughout the winter, and the den structure remained stable. On southwestern Kodiak Island with its gentler topography, bears denned at an average elevation of 1499 ft. (457 m) and preferred midslope habitats near alder thickets. The researchers believe that the alder roots help stabilize these dens that were dug in loose, unfrozen soil. It is important that a bear chooses an area for his den that will remain stable throughout the winter and won’t collapse, but dens often do collapse in the spring and summer after the bears have emerged, and the bears are forced to dig new dens the following fall.

Before a bear digs and enters his den, he eats a large amount of food to build his fat layer. Berries provide natural sugars, and a bear may gain as many as 20,000 calories per day from eating berries in the late summer and fall. Bears also drink large quantities of water and consume foods high in protein, such as salmon. Brown bears add six to eight inches (15.24 to 20.32 cm) of fat before hibernation. They stop eating shortly before they enter their dens.

During hibernation, bears do not eat, urinate, or defecate. They curl up to conserve heat, but they may change position in the den. They are sensitive to their surroundings, and hey may awaken and move about or even temporarily leave the den. Pregnant sows give birth while in hibernation, and they can lactate to nurse their cubs. They can also lick and groom their cubs.DSC_0208

Bears emerge slowly from their dens in the spring. A bear may go in and out of his den many times over the course of several days before leaving his den for good. This is especially true of sows with newborn cubs who may stay near the den for one to two weeks, slowly allowing the small cubs to adapt to the outside world. Upon emergence, bears are groggy and sluggish, and it takes time for their bodily functions to return to normal. Soon after leaving the den, a bear will pass a fecal plug that may be as long as two feet in length (61 cm). This plug consists of digested food that has accumulated in the lower intestine as a result of not defecating all winter. After leaving the den, bears drink large quantities of water and slowly begin to eat new plant shoots.

Next week I will write about the amazing physiological adaptations bears employ during hibernation and how and why these adaptations are being studied by human medical researchers.

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Kodiak Bear Growth

Kodiak Bear, Kodiak Wildlife, , , ,
Kodiak Bear Sow Nursing Her Cubs
Kodiak Bear Sow Nursing Her Cubs

Last week I gave you an update on the orphaned cubs we rescued a year ago, and I reported that the cubs weighed only 12 lbs. (5.45 kg) when we rescued them, but they now weigh 175 lbs. (79.54 kg). Is this normal; do Kodiak bear cubs in the wild gain that much weight in one year? The answer to this question varies and is dependent on many factors, including the mother’s physical condition. Was she able to eat enough berries and salmon to provide her with adequate nutrition to care for her cubs, and did she catch so many salmon that the cubs were able to eat a few of the scraps to supplement the milk she fed them? As with humans, some sows are better mothers and providers than others. Older sows with more experience tend to do a better job than young sows providing for their young. If the mother cannot find enough food for herself, she usually drops one of the cubs. Sows often leave the den with three or four cubs but may only have one or two by the end of the first summer. This sounds cruel, but if the mother senses she cannot feed three cubs, she must sacrifice one to save the other two.

Cubs of the Year (COY)
Cubs of the Year (COY)

Under normal conditions, a Kodiak bear cub’s weight doubles every two months during the first year. By their second summer, yearling cubs weigh approximately 135 lbs. (61.36 kg). By the time they are two-and-one-half years old, the males begin to outgrow the females, and weights may vary greatly. Females average 212 lbs. (96.36 kg) And males average 225 lbs. (102.27 kg). Females reach their full adult size at approximately five years when they weigh between 350 and 500 lbs. (159.09 – 227.27 kg). Males continue to grow, gaining approximately 100 lbs. (45.45 kg) per year until they are eight to ten years old and weigh 500 to 1000 lbs. (227.27 – 454.54 kg) Kodiak bears gain weight and add fat in the summer when food is abundant and then burn off this fat during hibernation.

One-Year-Old Cubs
One-Year-Old Cubs

The largest Kodiak bear on record lived in the Cheyenne Mountain Zoo and weighed 1670 lbs. (757 kg.). In the wild, Kodiak bears are not easy to weigh. Biologist Vic Barnes set out to answer the question, “How big do Kodiak bears get?” With the assistance of hunting guides, he obtained the weights of several large boars and sows shot during spring and fall hunts. The largest three boars weighed 1245 lbs. (566 kg), 1483 lbs. (674 kg), and 1519 lbs. (690.5 kg). The largest female weighed 767 lbs. (348.6 kg).DSC00101

I plan to do more bear posts over the next few weeks, so don’t hesitate to ask me a question or tell me something you’d like to know about Kodiak bears. If I don’t know the answer, I’ll research it.

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Update on Orphaned Cubs

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I wrote a post a year ago about three orphaned cubs that entered our lives when a resident hunter killed their mother. Last spring, my husband, Mike Munsey watched a hunter shoot a bear near a den, but Mike didn’t know it was a sow with cubs until several days later when one of our guides saw a newborn cub peer out of the den. It is illegal to shoot a sow with cubs, but the hunter was apparently unaware the bear he shot had cubs. Mike called Alaska Department of Fish and Game biologist Nate Svoboda and asked for permission to rescue the tiny cubs from their den. The helpless newborn cubs had been without food and water for several days, and Nate didn’t think they would survive, but he gave Mike permission to attempt a rescue.

There is an abundance of bears in zoos across the country. Bears live a long time, and they eat a lot of food, so they are expensive to maintain. Not many zoos are looking for bears, and unless The Department of Fish and Game has a specific request from a zoo with a suitable bear-habitat exhibit, they cannot rescue bears from the wilderness, even if they know the bears won’t survive on their own. When Mike called Nate, he expected to be told to let nature take its course, and he was pleasantly surprised when Nate gave the go-ahead for the rescue.

Mike radioed our guide Harry Dodge and Harry, another guide, and one of our hunters climbed to the den and captured the three cubs. The cubs were caked with mud, dehydrated, and hungry. The guys each put a cub in his backpack and hiked down to the beach. From there, the cubs were brought back to our lodge where they spent the night. The following day, Nate and a local pilot flew out to our lodge, put the cubs in a big cage, and flew them back to Kodiak. From there, they were flown to the Alaska Zoo in Anchorage where they were nursed back to health.

The cubs stayed at the Alaska Zoo for several months, and we watched frequent videos of them on the nightly news as they continued to grow. The videos showed the cubs wrestling and playing, and the sight of them looking healthy and playful always brought tears to my eyes.

This past fall, two of the cubs were moved to the Wildwood Zoo in Marshfield, Wisconsin. A few months later, the other cub was sent to the Toledo Zoo. The Wildwood Zoo had just completed a beautiful, large bear enclosure, so the timing couldn’t have been more perfect, and the two cubs were greeted as celebrities in Marshfield. The zoo held a contest to name the cubs, and the winning names were: Munsey and Boda. Munsey was of course named after Mike, and Boda was named after Nate Svoboda. Check out the Wildwood Zoo website to see photos of Munsey and Boda, and while you are there take a look at the beautiful Kodiak Bear Exhibit. The cub that went to the Toledo Zoo was named Dodge after Harry Dodge, the guide who helped rescue the cubs from the den. Mike, Nate, and Harry are all very proud that the cubs were named after them, and we are thrilled that the little guys (all three are males) are thriving.

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When those dirty little cubs were visitors at our lodge, the largest weighed only 12 lbs. The latest report we received on the cubs at the Wildwood Zoo is that they now weigh 175 lbs. I’ve heard several people comment that it’s sad they couldn’t be re-released into the wilderness, but that was never an option. Cubs learn from their mothers how to interact with other bears, avoid danger, procure food, and how to hibernate. These bears have lived in zoos nearly their entire lives, and the Alaska Department of Fish and Game only sends bears to zoos with first-rate bear enclosures. These cubs now have the mission of teaching thousands of people about bears, about Kodiak, and about the Kodiak National Wildlife Refuge. I have no doubt that all three will do a good job.

The photo at the top of this post was taken last year when Nate was putting the cubs in the plane to fly them to Kodiak. The other photo in this post is of two unrelated one-year-old cubs and their mother. This photo was taken in August, so the cubs were a few months older than the orphan cubs.

Happy Mother’s Day to all you mothers.  It didn’t occur to me when I wrote this update that I would be posting it on Mother’s Day.  I hope you will find it a story with a sad beginning but a happy ending.

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Mystery Newsletter

Living in the wilderness on Kodiak Island, Writing, , ,

I have been ending my blog posts for the past few months with a reminder to sign up for my Mystery Newsletter, but I haven’t thoroughly explained what that newsletter is and why I write it.

Two of my main interests are biology and mysteries. In my novels, I try to combine these interests. My main character, Jane, is a fisheries biologist, and my mysteries are set in the wilderness of Alaska, where wildlife abounds. My blog posts mostly focus on the wildlife of Kodiak Island, with a few posts on my writing, my novels, and living in the Alaskan wilderness. I enjoy exploring these subjects, but I also wanted to write about mysteries and crime, and since I don’t have time to do another weekly blog post, I thought a monthly newsletter might work out well. Next, I had to think of an idea, and I decided to either write a short mystery every month or write about true crime. From all the true crime shows on television, I think there has to be a big audience out there intrigued by the evil deeds and misfortunes of others. I’m not criticizing; I watch Dateline and 48 Hours too, and I am relieved at the end of the show when the bad guy or gal gets locked away for a life sentence or two. True crime seemed like a good option for my mystery newsletter, at least for the first several months.

Since I live in Alaska, I decided to write about true crime in Alaska, but I wanted to do more than just report the brutal details of deadly crimes. I remembered a show I enjoyed that was on A & E several years ago called City Confidential. Each week the show profiled a murder in a U.S. town, usually a mid-sized city. The story was not only about the murder but also about how the crime changed the city, or why changes in the city created the right environment for this particular crime. By the end of the show, you learned the details of a crime, but you also learned something about the city where the murder was committed and the history of that city. That show made me realize how murderers can change the lives not only on of their victim’s families and friends, but they can affect a community and even a state.

This past month in my Mystery Newsletter I wrote about the crimes of serial killer Robert Hansen. Hansen preyed on women in and around the Anchorage area in the 1970’s and early 1980’s. This was the time during the construction and early operation of the Alaska oil pipeline when hordes of people moved to Alaska to either work on the pipeline or to find jobs that supported the pipeline employees. In addition to all the legitimate workers, this influx of people included mobsters, drug pushers, and prostitutes. Law enforcement in and around Anchorage was not equipped to handle the huge rise in crime. Conditions were perfect for a predator like Robert Hansen, and due in part to mistakes made by law enforcement, prosecutors, and judges, he was not caught and prosecuted as soon as he should have been. Hansen was smart, but he was not a criminal mastermind. He was simply in the right place at the right time. My newsletter about Hansen has as much to do with Alaska and the turbulent changes during that time as it does with the killer himself. Alaska did not have a decent crime lab before the Hansen case, but it now has one of the best crime labs in the country. Before the Hansen case, no protocols were in place for dealing with sexual assault crimes, but developing those protocols became a priority for the troopers while the Hansen case was proceeding. These changes would have happened without Robert Hansen, but there is an obvious cause and effect between his crimes and the immediate improvements in law enforcement in the state. Next month I will profile a case that happened just three years after Hansen was sentenced, and in this case, the Anchorage police force, crime lab, and FBI were at the top of their game, working together in perfect harmony to capture and prosecute the perpetrator.

I also try in my newsletters is to profile crimes that I think have an “Alaskan flair.” In other words, these are not crimes you are likely to see in New York or Chicago. In my first newsletter, I wrote about a crime where the neighbors in an isolated area of Alaska were gathering near an airstrip to meet their weekly mail plane, when one of the men opened fire on his neighbors. That crime directly relates to the rugged environment, long winters, and brutal isolation of living in the Alaskan wilderness. In my second newsletter, I told about the massacre of the crew of a fishing boat and a murderer that seemed to vanish into thin air. I hope in a couple of months to profile some murders that happened here on Kodiak, including one that took place this winter when a caretaker of a remote lodge murdered another caretaker. That crime hits close to home for me, but as with so many things that happen in the Alaskan wilderness, few facts have been reported.

If you haven’t signed up for my newsletter and these stories sound interesting to you, you can sign up at: http://robinbarefield.com.