Category Archives: Harbor Seal

Harbor Seal behavior and biology near Kodiak Island

Avian Flu Poses Threat for Wildlife in Alaska

In 2022, an avian flu strain reached the United States. Over the past year, more than fifty-eight million domestic poultry and thousands of wild birds have died from the viral H5N1 flu strain. According to biologists, it is the largest bird flu outbreak in U.S. history and doesn’t seem to be going away. As its name suggests, the virus mainly affects wild and domestic birds but can also infect mammals.

In Alaska, more than twelve hundred chickens and ducks have died from the avian flu, and it has killed more than two-hundred wild birds, including eagles, ravens, and shorebirds. Biologists have also found the virus in wild mammals, including bears and foxes. Migrating wild ducks and geese spread the virus when they defecate contagious droppings across the areas where they travel.

Scientists have no treatment for avian influenza, and the mortality rate is high for poultry and wild raptors such as hawks, eagles, and owls. Symptoms in diseased birds include fatigue, difficulty walking, nasal discharge, decreased egg production, and swollen combs or wattles.

Transmission to humans is rare, but flu viruses tend to mutate easily, so this disease could affect humans in the future. Scientists have already identified the virus in marine mammals around the world. Biologists have detected outbreaks among seals and other marine mammals in Maine, Chile, and Peru.

The remoteness of most areas in Alaska makes it difficult for biologists to know how widespread the disease is here. In October 2022, researchers found a sick black bear cub in Glacier Bay National Park that tested positive for the H5N1 virus. A month later, a deer hunter on Kodiak Island collected the carcass of a dead brown bear cub that tested positive for the virus. A necropsy on the brown bear cub revealed infection in the cub’s brain, lungs, and liver. Biologists suspect both cubs scavenged on wild birds that had died from influenza and inhaled the virus while tearing the birds apart. Luckily, at this point, the virus cannot be transmitted from bear to bear.

Kodiak bears are at risk if a deadly novel virus spreads among them. A 1998 study on the genetic diversity of North American brown bears indicated that Kodiak bears have less genetic diversity among them than other populations of North American brown bears. Several of the genetic samples from bears on Kodiak showed identical genotypes, meaning the bears were so genetically similar that biologists could not measure the differences between them. According to a 2006 report conducted for the Kodiak National Wildlife Refuge, the genetic variation among Kodiak bears is much lower than the variation found among any other brown bear population. While the Kodiak bear population presently remains healthy, this low genetic variability makes this population susceptible to decimation by novel parasites or pathogens, which could reach Kodiak and infect bears.

If you see a sick wild bird in Alaska, report the animal to a hotline managed by the U.S. Fish and Wildlife Service at 866-527-3358 or by email at ak_mbm@fws.gov. In particular, look for signs of disorientation, twitching, or tremors, and birds with necks twisted back.


For those of you in the Anchorage area, I have a book signing at Barnes and Noble on Saturday, May 27th, from 1-5 p.m. Please stop by and say hi. I would love to meet you. I will be at Mosquito Books at the Anchorage airport on Tuesday, May 30th.


Robin Barefield is the author of five Alaska wilderness mystery novels: Big Game, Murder Over Kodiak, The Fisherman’s Daughter, Karluk Bones, and Massacre at Bear Creek Lodge. She is also the author of the non-fiction book Kodiak Island Wildlife and the true-crime book Murder and Mystery in the Last Frontier. Sign up below to subscribe to her free monthly newsletter on true crime and mystery in Alaska, and listen to her podcast, Murder and Mystery in the Last Frontier.

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In Conclusion

When I reach the end of a manuscript, I dread writing the conclusion because a conclusion requires a great deal of thought and effort. Just as we were nearly done polishing my non-fiction book, Kodiak Island Wildlife, the editor said he believed the book needed a conclusion, and I groaned, but I also agreed with him.

I don’t know how long I stared at a blank computer screen, but I could think of nothing to write. How do you sum up a book about wildlife? Then, as I stood on our boat one morning, watching giant fin whales with our guests, the conclusion for my book popped into my mind, fully formed. When I read it to my husband, tears came to my eyes, and I knew I had done my best work. My editor agreed, and he said it was the perfect ending. The following is the conclusion for my recently released book, Kodiak Island Wildlife.

Emerald cliffs plunge into the gray ocean, and only a slight breeze stirs the surface of the water. In front of our boat, three huge fin whales feed, frequently surfacing to breathe. Their exhalations sound like cannon shots, and our guests capture every moment with their cameras. A sea otter bobs placidly a short distance from our boat, and a bald eagle circles overhead. I have seen all of this many times, but still, it takes my breath away, and a chuckle escapes my lips. How have I managed to live my life in one of the most beautiful places on the planet? To me, Kodiak is paradise. Sure, the weather here throws frequent tantrums, and mistakes in the hostile wilderness do not go unpunished, but I have found nowhere else I would rather live.

One of my greatest joys is to guide visitors into the Kodiak wilderness. I love the look on a newcomer’s face the first time she sees a Kodiak bear or watches a sea otter eat a crab. I wrote this book to honor the wild animals we’ve watched over the years and to thank the many folks who have visited our lodge. I know they would tell you that Kodiak is a special place. The island is mysterious and magical.

It is a short conclusion, but it sums up how I feel and accurately describes my motivations for writing the book. I am grateful for the many experiences I’ve enjoyed. My life is an adventure filled with wonder in the Kodiak wilderness, and I can’t imagine living anywhere else.


Speaking of wildlife, I hope to return to regular and more frequent posts soon. The past two months have been hectic. I’m writing this while I sit on our boat. We are cruising 100 miles around Kodiak Island from our lodge to the town of Kodiak, where we will have our boat lifted out of the water so that we can clean and paint the bottom. As soon as we return home, we have endless jobs awaiting us before our summer season begins. Meanwhile, I am trying to promote my new book and keep up with my scheduled newsletters and podcasts. I realize I’ve let my blog posts fall through the cracks, and I vow to make my posts more of a priority in the future. Thank you for your patience.


Kodiak Island Wildlife is now Available


Robin Barefield is the author of four Alaska wilderness mystery novels: Big Game, Murder Over Kodiak, The Fisherman’s Daughter, and Karluk Bones. Sign up below to subscribe to her free, monthly newsletter on true crime and mystery in Alaska, and listen to her podcast, Murder and Mystery in the Last Frontier.

Listen to my podcast about true crime and mystery in Alaska.

Mystery Newsletter

Sign Up for my free, monthly Mystery Newsletter about true crime in Alaska.

Mammalian Diving Reflex

The mammalian diving reflex is a fantastic biological adaptation intrinsic not only to marine mammals but also to land mammals, including humans, whose ancestors once lived in the ocean. I am currently editing my wildlife book and was once again awed by how deep some marine mammals dive and how long they can stay below the surface without breathing. I think the mammalian diving reflex represents one of nature’s most incredible adjustments for air-breathing mammals required to find food in an inhospitable environment void of air.

What is the mammalian diving reflex? Biologists mostly have studied the reflex in harbor seals, so I will use a seal to explain the elements of the physiological changes. A harbor seal can dive as deep as 1640 ft. (500 m) and stay submerged for over twenty minutes. When it dives, a harbor seal’s heart rate slows from its normal rate between 75 to 120 beats per minute down to just four to six beats per minute. Blood shunts from peripheral tissues tolerant to low oxygen levels and flows to the heart, brain, and tissues dependent on a constant supply of oxygen to survive. These adaptations allow the seal to conserve oxygen while it dives and searches for food.

Seals utilize additional adaptations to conserve oxygen and withstand the rigors of increased pressure when they dive. Before a deep dive, seals exhale several times to collapse their lungs, and they then store their oxygen in blood and muscle tissues instead of in the lungs. Harbor seals have a proportionately higher blood volume than land mammals of the same size, and seals also possess ten times more myoglobin than humans. This oxygen-binding protein helps prevent muscle oxygen deficiency.

Researchers originally believed the diving reflex was an automatic response triggered by breath-holding and submergence in cool water. In recent studies, though, scientists attached a device similar to a Fitbit to harbor seals. The device records blood flow and oxygen levels in the seal’s brain, and the study produced some interesting results. Seals can control their diving reflex. Seals contract their peripheral blood vessels beginning 15 to 45 seconds before they dive, and they restore normal blood flow to their blubber several seconds before they reach the surface. When seals are feeding, they return to the surface to breathe but often don’t stay there long enough to restore normal oxygen levels. Researchers also learned that seals slow their heart rates more if they plan to stay underwater longer.

Biologists hope to learn if other animals, including humans, can also consciously control their dive reflex. The world’s top freedivers can descend to a depth of 426 ft. (130 meters) and return to the surface, and the record for breath-holding without moving tops 11 minutes. Are these free divers able to control the physiology of the diving reflex to accomplish these incredible feats?

The next time you see a harbor seal, pause for a moment to consider the rigors this animal must endure just to eat dinner.


I hope you are well and navigating our changed world. Life remains quiet here in the wilderness of Kodiak Island, and we feel oddly removed from the biological havoc wreaked by this virus. Even here, though, we have been touched by the economic disaster the world faces. I look forward to better times for all of us soon!  Take care.


Join the Battle of the Books contest, and you could win a $500 Amazon Gift Card! I am very excited to have my novel, Karluk Bones, included in this contest.

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Robin Barefield is the author of four Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter, and Karluk Bones. You are invited to watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska, and listen to her podcast, Murder and Mystery in the Last Frontier.

Mystery Newsletter

Sign Up for my free, monthly Mystery Newsletter about true crime in Alaska.
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