Q & A: The Bears of Brooks Falls Book Club

Bearcam is back for 2021, and while it’s still very early in the season several bears—including Grazer, Holly, and their yearlings—have made an appearance. As Rangers Naomi Boak and Lian Law discussed with me during our Welcome to Bearcam live chat, there are many fascinating storylines to follow this year. At the risk of offering a shameless plug, my book, The Bears of Brooks Falls, explores many of those stories too.

A dedicated book club has sprung up to discuss the book. At the end of each meeting, participants answer one question: If you could ask the author anything, what would be? Below, I’m happy to answer those questions. If you are interested in joining the book club for their next discussion on June 19 via Zoom, please sign up.

Questions from the club’s discussion of Part One: Creation and Discovery (May 29, 2021)

Can you clarify WHY there used to be fewer bears at the falls? In the past, were they hazed away? Did they stay away from the falls because anglers were given priority there?

In Part One of my book, I discuss the events that led to the proclamation of Katmai National Monument in 1918 and the monument’s evolution into one of the largest national parks in the United States.  Bears were not a major tourist attraction at Brooks River until long after Brooks Lodge was established. It wasn’t because anglers were given priority. It was because the bear population was much smaller than today. The national monument was expanded in 1931 to include areas such as Brooks River to protect habitat for wildlife like bears, but:

By all accounts, few bears used the river when Brooks Lodge first opened for business in 1950. Bears and any type of bear-management activities were absent from the reports of the first rangers stationed at Brooks Camp. Ranger Russell Todd, for example, never saw a bear on foot in the summer of 1954. The presence of people alone was apparently enough of a deterrent to displace bears from the river except at night. In 1957, biologists conducting salmon research at Brooks River for the US Fish and Wildlife Service reported bears “loudly evident” every night during September at the salmon- counting weir strung across the head of the river.

How many bears lived within the monument at that time remains an open question, but it was likely not many. The population may even have been at a nadir, the result of decades of heavy hunting pressure near the monument and, I suspect, the lingering effects of the 1912 eruption. After a two- summer biological investigation of the monument in 1953 and 1954, Victor Cahalane reported: “It is impossible to make even a rough estimate of the population of bears in Katmai National Monument.” Yet he tried. According to his and other anecdotal sightings, including one from a pilot who claimed to have seen 60 bears along Savonoski River in early September 1954, Cahalane ventured that about 200 bears lived in the monument.

Steady levels of salmon and a reduction in hunting pressure outside the monument were probably the main factors that allowed the area’s bear population to slowly increase, but at Brooks Camp people inadvertently helped accelerate the bears’ use of the river. By the end of the 1960s, a small and growing contingent of bears had become accustomed to the easy access to unsecured food at nearby garbage dumps, the lodge’s burn barrels, and unsecured supplies. By the mid- 1970s, Brooks Camp had become well known as a place to find at least a few bears, and several had begun to fish in the river during the day when people were active. (Pg. 172-173, The Bears of Brooks Falls)

I will add that over the last 40 years, salmon runs in the Naknek River watershed have been quite strong and that, perhaps more than anything else, has allowed the bear population to increase in the park. Additionally, during much of that time, park staff management have emphasized minimizing bear-human conflicts. The experience of cubs that accompanied their mothers to Brooks River may now consist largely of relatively benign contacts with people. This probably allowed the number and proportion of adult bears tolerant of people to increase.

It sounds, from Mike’s description [in Chapter 3 — Ramble], that the outlet of Brooks Lake into Brooks River is pretty shallow. Could global warming threaten the snowfall on the mountains, dropping the level of the lake and halting the flow of the river? If so, could that be a risk in the near future?

Although I can only provide a speculative answer, and while Lake Brooks will be affected by a warmer atmosphere, its water flow may not change appreciably. Lake Brooks occupies a deep basin that is almost completely below the water table of the surrounding land. There are no glaciers in its headwaters, unlike nearby Naknek Lake, so it’s already adapted in a sense to a hydrology that is highly influenced by annual precipitation. Snowmelt is only one influence. After most of the snow melts from the watershed in late spring, then summertime rain seems to have the biggest influence on water levels in the lake. Wetter summers can raise lake levels more than a foot compared to dry summers. Importantly, much of its water is sourced from spring-fed streams and springs under the lake surface. So, even during drought years, the lake basin experiences some recharge.

Climate change is certainly altering Katmai’s landscape, both the land and water. In 2019, we saw the impacts of a very hot, dry summer on Brooks River. Water levels were quite low and water temperatures were quite hot during an early July heat wave that year. However, water continued to flow through the river, albeit at a reduced level.. That’s just one year, though. By the end of the century—especially if we don’t get our act together and reduce our greenhouse gas emissions as quickly as possible—the summer of 2019 will be one of the coolest of this century. Droughts and heat waves may become the norm in Katmai. For more information on the present and future of Katmai’s climate, please see chapter 17 of The Bears of Brooks Falls.

Can you clarify the distance from Brooks River to Margot Creek? Is it common — or uncommon — to see “our” cam bears at Margot Creek?

The shoreline of Naknek Lake between Brooks River and Margot Creek is about 13 miles, well within a day’s walk for a brown bear. If a bear takes a few shortcuts through the forest, then the walk is closer to 10-12 miles.

Google Earth image showing relative locations of Brooks Falls (upper left) and Margot Creek (lower right). Thickly vegetated land surrounds milky blue lake. North is the top of the map. The scale at lower right is 2 miles

Several identifiable Brooks River bears use Margot Creek in August including 402, 435 Holly, 480 Otis, and 856. I would not be surprised if there are others well. But, salmon are dispersed widely in central Katmai in August when bears fish at Margot Creek. Unlike early summer and early fall when Brooks River is the only place to fish, bears have many other alternatives to Margot Creek in mid summer so not all Brooks River bears need to go there.

Can you talk about your research process? The book draws on your personal experience — but it clearly draws on extensive research, too. 

When I began drafting the manuscript, I thought most of my research was finished since I had to study a lot to prepare programs and talk about bears when I was a park ranger at Katmai and through my current job at explore.org. That head start was helpful but not thorough enough. It was merely the foundation to build upon.

As I wrote, I wanted to be sure that my facts and conclusions were backed up by personal observations, experience, and the best available science. While working on the manuscript, I probably spent half my time reading research and half my time writing.

I began writing each chapter by outlining it. Then after I established what I wanted to write about and the stories that would add depth to the facts, I read or skimmed through the relevant books and scientific papers that I saved previously to establish the basic facts that I wanted to include and confirm what I thought I knew. This led me down many rabbit holes. I probably read dozens of papers for some chapters, especially Chapter 4 on hibernation. Tracking down specific facts and, hopefully, ensuring that I represented them accurately in the book was a tedious yet necessary task. Readers deserve no less.

Not a bear question, but a question for you as an author: What did it hurt to leave out of the book? What did you have to omit that you wish you’d been able to keep?

Quite a lot, actually. For example, I drafted chapters on glaciation and the evolution of Brooks River, but after consulting with an editor I decided to cut those. They weren’t a great fit for the narrative I tried to build. I also wanted to include the story of Holly adopting a yearling 503 in 2014 but couldn’t find the right place for it when I outlined the book. I considered using that story as the framework for Chapter 5: Family, but since adoption in bears is so uncommon I thought it best to focus on a bear whose maternal experiences were engaging yet more typical. That’s how I settled on 273 and her cub for Chapter 5. I’m happy with the final result of that chapter, yet I still wish I had found a way for Holly to be a part of it.

Questions from the club’s discussion of Chapter 6: Mating Season (June 6, 2021)

What if a female [bear] doesn’t want to mate? How much “say” does she have in the decision?

The female bear can’t control estrus or the signals that indicate to males that she is in estrus. However, female bears seem to have a lot of say in the timing of copulation. Although male bears are much larger than females, I’ve never seen a male bear force himself on a female bear. Instead, he doggedly follows her until she is ready to accept his advances. I also wonder if prolonged courtship can provide female bears with the chance to shed a suitor that they do not prefer. As I write in the book, a bear’s sense of smell is so powerful that a female can’t hide from a male. But, since mating opportunities are so limited for males, it’s not uncommon for more than one male to catch the scent of an estrous female. A prolonged estrus cycle coupled with a lengthy courtship could increase competition between males—an unconscious way for her to attract the most “fit” mate.

What is the ratio of males/females at Brooks River?

It hovers near 50:50, but last year there were more females than males. Because large adult male bears occupy the most productive fishing spots at Brooks Falls, it can sometimes seem like there are more males on the river than females. In July 2020 park bear monitoring staff identified slightly more female bears than males (29 adult females, 22 adult males, 14 subadult females, 11 subadult males).

Can you talk a bit about inbreeding? It seems like a lot of the bears we see mating are likely related to each other…

There’s only one confirmed case (through DNA analysis) of consanguineous couplings (inbreeding) between related bears at Brooks River.

24 BB was a very dominant male bear at Brooks River from the late 1990s through 2007. He was the equivalent of 856 during that time, and because of his dominance few bears would ever challenge him for fishing spots or for access to estrus females. BB sired a litter with the female 209. Bear 402, who still uses Brooks River, was one of the cubs from that litter born in 1998. 24 BB then sired a litter with 402. The offspring from the 402/24 relationship were weaned by 402 and identified as independent bears, but have not been seen in many years. I should note that this is common among subadult bears and their absence may not be reflective of interbreeding between a father bear and a daughter bear.

The limited DNA analysis of bears in 2005-2007 did not document any litters from a mother/son relationship. I think it’s unlikely that a bear could mate with its mother for a couple of reasons. 1. Male bears compete for the opportunity to mate with females and a larger, more dominant male would certainly outcompete a younger male bear for access. So while a young male bear is mature enough to mate around age 6, he’s still quite small compared to older males. 2. Young male bears often disperse away from their mother’s home range, and consequently their ranges as adults might not overlap. Mother bears remember who their offspring are too, and mom is often intolerant of the approach of her former cubs (we sometimes see a mother charge her former cubs, even years after family breakup, almost as if she is saying, “I told you to leave. Now stay away”).

Katmai’s brown bear population is quite large and robust. About 2,200 bears were estimated to live wholly or partly within Katmai National Park and Preserve in 2007. Although, we don’t know its true frequency, inbreeding between bears is probably uncommon here since the population is so large.

Why do mating males want to keep females in sight? It seems like all this following females around would distract males from eating and getting fat.

Courtship between bears isn’t always a prolonged process. In fact, sometimes bears couple soon after meeting. Potential male suitors, therefore, need to guard access to their prospective mates, lest they lose a rare mating opportunity.

The pursuit of mating opportunities certainly distracts male bears from other life tasks like fishing for salmon. I remember one July when 856 seemed like he didn’t stop courting females for the entire month. While the other males at the river got their fill of fish, 856 fished only occasionally because he was more interesting in reproduction. Near the end of July, he looked well muscled from the exercise of the pursuit but looked as though he had little body fat.

A large brown bear stands in shallow water. He looks toward the left side of the photo. A partly eaten salmon rests at his front paws.

856 often spends a lot of time courting females in early summer and less time fishing compared to many other adult bears. He can afford to do so because his high level of dominance provides access to fishing spots wherever he goes.

“Survival of the fittest” is often thought to refer to athletic fitness or survival instincts, when it is more accurately framed in terms of reproductive fitness. Perhaps the male bears who have the energy reserves and stamina to court female bears for long periods of time with little food are the most reproductively fit. It’s also important to consider that the bears’ mating season ends in early summer, just when food becomes plentiful in Katmai, so a male who doesn’t eat much in June has ample opportunities to make up for it during the next few months.

Questions from the book club’s discussion of Chapter 14: Boundaries (June 12, 2021)

Is there any research showing how reduced attendance during the 2020 pandemic affected the salmon and/or the bears?

As far as I know, there’s nothing publicly available yet. However, biologists at Katmai National Park expanded the bear-monitoring program last year to collect data that might help answer that question. It was an unexpected research opportunity to observe bears at Brooks River at a time of year when typically it is loaded with people.

Certainly the lack of people at the river in 2020, especially when the camp remained closed to the public, allowed bears more space to fish. The greatest influence on the distribution of bears last year, though, was salmon. The record run of sockeye salmon was overwhelming and it provided bears with ample feeding opportunities throughout the river. In a year with fewer fish, I don’t think we wouldn’t have seen bears using the lower river in early summer as much as they did in 2020, no matter how few people visited.

The bears at Brooks are perhaps more human-habituated than other bears. And yet, as 854 Divot’s story proves, they do wander outside the boundaries of the park, where they will encounter humans who don’t operate according to park rules. Can you offer some reassurance — or some insight — about how their human habituation might affect their fate outside park boundaries?

Habituation at Brooks River provides a bear with advantages. It allows access to parts of the river that may otherwise be off limits if the bear isn’t tolerant of people. At Brooks River, people are especially tolerant of bears too through both attitude and regulations designed to protect bears.

Outside the park, they may not encounter the same tolerance. Having a bear prowling outside your cabin at Brooks Camp is one thing. Having it do so near your children and pets is another.

If a habituated bear wanders into King Salmon, for example, its tolerance for humans may lead it to temptation in the form of unsecured food and trash. A habituated bear could more easily become conditioned to seek human foods in that situation. Bears encounter much greater risks around people in those places than they do at Brook Camp.

Some biologists I’ve spoken to speculate that habituation could be context specific. That is, a bear might be able to learn that people in one location are tolerant while people in another location are dangerous. I think this is plausible but I’m not yet convinced it works that way for most bears. Further research is needed.

Questions About The Bears of Brooks Falls?

It’s been two months since my book, The Bears of Brooks Falls, was released for your reading pleasure. Whether you’re fortunate enough to visit Brooks River in person or if you are a fan of the Brooks River bearcams on explore.org, I hope the book will become a valuable companion to your bear-watching experience. I’ve been pleased to find many people have enjoyed it and found its storylines to be enlightening.

I also hope it’s provoked your curiosity about bears, salmon, Katmai National Park, the history of national parks, and the evolving role that people play in parks and other wild landscapes. With bearcam season right around the corner (expect the cams to go live in mid to late June), I’m also coordinating with bookstores to host online talks about the book.

There’s been no designated place for readers to ask questions about the book though, so let this post serve that purpose. If you have a question or a comment about something you read in The Bears of Brooks Falls, then please drop it in the comments. I’ll do my best to reply. And, of course, I’ll be online almost everyday during bearcam season to answer your questions about bears and salmon as the resident naturalist with explore.org.

a small brown bear cub clings to the side of a spruce tree. more spruce trees and foliage fill the background.

The Bears of Brooks Falls Unleashed

Many years ago, inspired by the complicated and fascinating intersection of bears, salmon, and people at a most unique place, I conceived the idea of a book that captured the story of Brooks River in Katmai National Park.

 Today, I’m pleased to announce that The Bears of Brooks Falls: Wildlife and Survival on Alaska’s Brooks River is now available.

Part one of The Bears of Brooks Falls explores the establishment of Katmai National Monument, from the moments preceding the largest volcanic eruption of the 20th century to the discovery of the surreal Valley of Ten Thousand Smokes. These events inspired the creation of Katmai National Monument and, soon after, the efforts to expand the park for wildlife like brown bears.

Today, Katmai is most famous for its brown bears. Part two is devoted to their lives as well as the salmon that the bears depend on for their survival. I explore the marvel of the hibernating bear, discover Brooks River from a cub’s perspective, and follow the tribulations and growth of young bears recently separated from their mother. I also ponder how Katmai’s brown bears experience reproduction, competition, hunger, and death.

Few organisms are as important to an ecosystem as sockeye salmon are to Brooks River. These fish face tremendous obstacles and challenges. From freshwater to the ocean and back again, they travel thousands of miles, running a gauntlet of predators to fulfill their destiny. The journey ends when they sacrifice their lives to reproduce. Salmon are Katmai’s keystone, driving Brooks River’s productivity and significance.

In part three, I examine modern humanity’s influence over Brooks River. Humans may be the river’s biggest wildcard. Climate change looms large over the land and seascapes, and people alter the behavior of the bears that make the scene so special. The infrastructure needed to support thousands of visitors and their recreational activities invites conflict with bears. Managing bears and people in such a small area is especially challenging, provoking a decades-long and often emotional debate about the river’s future.

Brooks River’s bears live in a land that straddles the border between the wild and human realms. Their lives are intertwined with ours, and as a result Brooks River is a microcosm for many of the issues facing our national parks. No book has captured this story before.

Order your signed copy through the Katmai Conservancy, the official non-profit partner of Katmai National Park, and join the book release live event on March 9 at 8 pm ET / 5 pm PT on explore.org’s live events channel.

I’d also love to know what you think of the book. Drop a comment in response to this post, email me, or post a review on the websites of major booksellers.

Happy Reading,
Mike Fitz

Book Cover. Background image shows three bears at edge of waterfall while one salmon jumps out of the water. Text is "The Bears of Brooks Falls: Wildlife and Survival on Alaska's Brooks River; Michael Fitz"

Bear Necessities Intensifies: Lessons from a Semi-Viral Video

In September 2017, I took a brief trip to Brooks Camp, the world-famous bear-viewing site in Katmai National Park. This was a rare opportunity for me to visit for fun, as opposed to traveling there to work for the National Park Service or explore.org.

Bear watching is the most popular human activity at the river and the close proximity of Brooks River’s brown bears to the designated wildlife-viewing platforms makes for some exceptional photographic opportunities. However, I toted only a small point and shoot camera with a limited zoom. Taking good photographs, therefore, was challenging so I focused more on recording video of bears. Video can also provide a sense of scale that is sometimes difficult to capture in photos, especially when a titan is in the vicinity.

On the last morning of my trip, I found the colossal 747 walking out the river to challenge a competitor at Brooks Falls. This is what happened.

After I uploaded this video to YouTube, I hadn’t expected it to garner much attention, but a little more than three years later Giant Fat Bear at Brooks Falls is approaching one million views and has generated more than 3,500 comments.

When a video goes viral or becomes modestly popular, you can either let it develop a life of its own or attempt to heighten the experience. A captivating video is a chance to give people more than a few seconds of entertainment. It presents an opportunity.

People are naturally curious, especially so toward animals, but context and relatable, meaningful information are often needed to match that curiosity. How might those in the fields of heritage interpretation or science communication provide the casual viewer with a more meaningful experience? Here are a few of the strategies that I found successful with a short video about a fat bear.

Anticipate what a person with no context of the place or subject might need to know. The universe is a big place. Put yourself in the mindset of someone who does not have your experience or background. Although people relate to brown bears easily and on many levels (they definitely love a chonky bear), the natural history and ecology of these animals are not universally or even well known. I soon realized my modest video description was inadequate. Viewers were drawing conclusions and asking questions that I had not anticipated. They wanted to know more.

Get to know the demographics of your audience. If you read this blog regularly, you’re familiar with the bearcams in Katmai National Park. While the bearcams are extremely popular, receiving tens of millions of views each year, explore.org’s webcam analytics document that the bearcam audience skews heavily toward the female gender and adults over the age of 45. Analytics on Giant Fat Bear at Brooks Falls, however, are much different. Viewers are typically 18 – 35 years old and overwhelming male.

Screen shot of video analytics. Text says "Age and gender | Views Since uploaded (lifetime) | 13-17 years 0.8% | 18-24 years 22.4 % | 25-35 years 37.4% | 35-44 years 15.9% | 45-54 years 10.2% | 55-64 years 7.9% | 65+ years 5.4%

That audience will likely react to and evaluate information differently than the typical bearcam commenter. And, they are relating to different things in the bear world. Knowing that, I might respond to questions and comments on the video in ways that I wouldn’t during a live chat on the bearcams.

Screen shot of two comments from a youtube video. Text says: 

Swamp Fox1 month ago
"This is a very large adult male (look closely when he stands up and rubs his back on the tree)." I did what you said. I guess that water's even colder than it looks.

Mike Fitz
4 weeks ago
@Swamp Fox The water in Brooks River is often a chilly 50 degrees F in early September. It likely has an effect. However, the bears' mating season peaks in late spring, so by late summer when I recorded this video testosterone levels in male bears aren't as high as they were before. Bears are also equipped with a baculum, which probably helps provide greater endurance when they need to get the job done.

If a video generates a lot of similar questions or leads people to make assumptions, write an FAQ to address those and then put it some place obvious. When the views on Giant Fat Bear at Brooks Falls began to skyrocket, I took mental notes on the questions it generated to see if there was a pattern, while keeping in mind that the internet is a big place where people from all over the world can access the video. In addition to the questions people were asking, the number of comments prompted me to consider how I could provide further context. I identified three questions originally, wrote concise answers for them, and pinned the FAQ to the top of the video comments.

The FAQ didn’t stop people from asking questions (and I didn’t it want it to), but it caused the queries to change. Questions became less repetitive. They branched to other facets of bear biology. Plenty of people appear to be reading the FAQ as well. As of this writing, the FAQ on Giant Fat Bear has 2.8 thousand likes and zero dislikes.

The FAQ proved to be particularly valuable in ways that I did not expect. Much of the internet is little more than websites recycling (to state it mildly) the work of others. When the video first began to trend in 2018, the FAQ was often the only source of info used by websites looking to generate click-bait content based off my video. It was used in the prestigious Daily Mail, for example, to produce one of the tabloid’s most fact-laden articles ever.

When in doubt, assume that a person asks questions in good faith. It’s not always easy to discern the difference between questions asked in good or bad faith, and trolls should not be engaged. However, each person experiences life through the lens of a unique worldview and knowledge base. Furthermore, access to open space and outdoor recreation (both physically and inclusively) is far too limited for many people, especially among those that experience racism and discrimination. Yet biophilia and an instinctual curiosity reverberates through each of us, and by asking a question a person signals that they want to learn.

This is why I included “Are you making fun of the bear’s fatness?” in the FAQ. It’s not dumb to not know much about bears. Most of us don’t have easy access to bear habitat, let alone the opportunity to observe wild bears. People also post a lot of offensive stuff online. Given the unfortunate status quo of social media, I don’t fault anyone for thinking I might’ve been making fun of a fat bear instead of simply describing him. It is not obvious to everyone that bears must get fat in order to survive.

Think carefully about offers to license your content. Video distribution agencies prowl social media sites looking for engaging videos to add to their collections. Their offers to license and distribute your video look appealing at first glance, but I eventually rejected them all. Providing meaningful information and context was more valuable to me than the ten cents I might make through a third party distributor. I was particularly hesitant because some viral media companies distribute wildlife videos and spread them without context or even checking to see that video was recorded ethically. By rejecting these solicitations, I sacrificed reach but remained in control of the flow of information.

Lastly, choose a catchy title for your video but also one that isn’t confusing. Some comments on Giant Fat Bear at Brooks Falls suggest that a handful of people read the title literally and expected to see a giant fat bear fall.

Screen shot of comment on YouTube video. Text reads, "Mementø Møri 3 months ago (edited)
I was waiting all the video to see this bear falling.. But then I realized that I understood the title wrongly."

I’ve greatly enjoyed seeing how this simple video has inspired interest in bears, art, memes, and eventually helped to propel 747 to Fat Bear Week greatness.

As I draft this post, Giant Fat Bear continues to generate questions and comments. Many of the comments are simple jokes, but I still count those as a win. It means that a person was engaged. For those few seconds (and more if they asked a question) they were thinking about bears.

screen shot of youtube comment. text says, "SSSTYLISSSH SSS e months ago (edited) He protect He attack But most important He likes to snack"
Jumpstart 2 months ago he protecc he attacc but most importantly he scratch bacc
Screen shot of youtube comment. Text says, "Gladhe 1 month ago He protecc He attacc He most importantly Eat big mac!]

I have no allusion that leaving a comment on a video is the same as stewardship and advocacy for wild animals. But the first step towards stewardship is awareness and understanding. As Freeman Tilden, the founder of modern heritage interpretation, wrote in Interpreting Our Heritage, “Through interpretation, understanding; through understanding, appreciation; through appreciation, protection.” We get there one step at a time and we get there more easily with guides along the way.

The Bears of Brooks Falls: The Book

I first traveled to Brooks River within Katmai National Park in early May 2007, and today it’s hard for me to imagine my life without it.

On the morning of my first flight to Brooks Camp (which is only accessible by boat, plane, or a very long, boggy, buggy, and rough cross-country hike), fellow rangers and I hauled our clothing, equipment, and months of food to the floatplane docks along Naknek River in the small town of King Salmon, a sprawling community surrounding an airport and mothballed U.S. Air Force base. We were excited and enthusiastic to begin the adventure, but few of us, I believe, truly understood what we were getting ourselves into. I certainly didn’t. Not quite a greenhorn when it came to wild areas, I had never experienced a landscape like this.

Immediately after takeoff, I gazed out the window of our small plane, my eyes transfixed on what many people would describe as nothing. King Salmon’s few houses, roads, and infrastructure quickly yielded to tundra and scattered spruce trees. This was land devoid of permanent human habitation. Cross hatching animal trails led to unknown destinations. I saw wildly meandering creeks, too many ponds and lakes to count, and a horizon bounded by unnamed mountains.

After twenty-five minutes of flying, the pilot landed smoothly on Naknek Lake’s calm surface, and we taxied to an empty beach in front of the few scattered buildings marking Brooks Camp. With the help of fellow staff, I hurriedly unloaded and stashed my gear inside a nearby tent frame cabin and began to settle in.

Later that evening, Jeanne, my then girlfriend and now wife, and I returned to the beach. I had just finished a winter job at Death Valley National Park, where daily temperatures had already risen above 100˚F, but Brooks Camp looked like winter couldn’t decide to stay or go. Leaves had not broken bud, thick blankets of snow clung to the mountains, and the underground water pipes to our cabin remained frozen. I walked wide-eyed, trying to take in the totality of the scene—the turquoise color of Naknek Lake, the snow-capped mountains, the pumice-strewn beach, a set of bear prints in the sand—when Jeanne waved her arm toward the horizon and remarked, “This is spectacular.”

I don’t recall if I responded or not. Doesn’t matter, because she was right. I had never looked upon land so empty yet so full.

Katmai and Brooks River are unlike any other place. But relatively little has been published about the bears, salmon, and humanity that intertwine at the river. In 2014, I first imagined an idea of writing a book about Brooks River and its inhabitants. In 2016, I began to work on it in earnest and this year I finished the manuscript. I’m pleased to announce my book, The Bears of Brooks Falls: Wildlife and Survival on Alaska’s Brooks River, is available for pre-order. It ships out in March 2021 via Countryman Press. In eighteen chapters, the book strives to explore the ecology of the river’s famed brown bears and salmon as well as the complex relationship people have with the place.

Part one focuses on the colossal eruption of Novarupta Volcano in 1912 and the discovery of the Valley of Ten Thousand Smokes. This event reshaped the area’s history and led to the establishment of Katmai National Monument in 1918, a time when the national park idea was still fledging.

Today, Katmai is most famous for its brown bears. Part two is devoted to their lives and the salmon the bears depend on to survive. I explore the marvel of the hibernating bear from a den on Dumpling Mountain, discover the river from a cub’s perspective, and follow the tribulations and growth of young bears recently separated from their mother. The brown bear mating season provides the chance to learn how bears compete during one of the most important times in their lives. Writing about the bear hierarchy, I consider how this social structure provides advantages to bears who live in an unfair world. Katmai’s brown bears experience hunger in a profoundly different way than people. They must eat a year’s worth of food in fewer than six months to survive hibernation. Their feeding choices and habits reflect highly tuned adaptations to take advantage of summer’s ephemeral bounty. And, the poignancy of a cub’s death, one witnessed by thousands of people on the park’s webcams, provides the chance to reflect on the end of a bear’s life.

Few organisms are as important to an ecosystem as salmon are to Katmai. Leading Odyssean lives, sockeye salmon face tremendous obstacles and challenges. From fresh water to the ocean and back again, they travel thousands of miles, running a gauntlet of predators to fulfill their destiny. Weakened by their freshwater migration and subsisting without food for weeks, the journey of Brooks River’s sockeye ends when they sacrifice their lives to reproduce. They are the ecosystem’s keystone, driving the river’s abundance and significance.

In part three, I examine modern humanity’s influence over Brooks River. Humans may be the river’s biggest ecological wildcard. Climate change looms large over the land and seascapes, and people alter the behavior of the bears that make the scene so special. The infrastructure needed to support thousands of visitors and their recreational activities invite conflict with bears. Managing bears and people in such a small area is especially challenging, provoking a decades-long and often emotional debate about the river’s future.

The Bears of Brooks Falls: Wildlife and Survival on Alaska’s Brooks River is an exploration of brown bears and salmon in one of the Earth’s last fully intact ecosystems. It’s an honest and deep dive into issues surrounding the role people play in the riverscape and Katmai National Park. And, I’m so excited for you to read it, and I hope you’ll consider adding it to your bookshelf.

2020 Fat Bear Week Endorsement

In a year of heightened political polarization, there’s one candidate that rises above the rest. He’s a candidate for greatness. A candidate for change. He campaigns on a platform of success, skill, efficiency, and hard work. He is known simply as 747 and he deserves your vote for Fat Bear Week.

Large brown bear seated in shallow water.

Seven-four-seven is a titan, a tank, and a giant among bears. Holly might pledge a “salmon in every paw,” but 747 pledges just to eat salmon.

Seven-four-seven’s size is legend. At the Brooks River, few bears approach his size class, and as a result he has consistently ranked among the river’s most dominant bears. His measured size even surprised me, however. Through a novel use of terrestrial laser scanning technology, he was estimated to weigh more than 1,400 pounds in September 2019. This summer he appears to be at least as large, but I suspect he’s even bigger.

A bear can’t get this big without eating a lot of food, and Brooks River provides 747 with ample opportunity to get fat. Brooks River is part of the Bristol Bay watershed, an area that supports the last great salmon run on Earth. While salmon runs throughout much of North America struggle to cope with the combined impacts of impassible dams, incompatible land-use changes, and climate change, Bristol Bay continues to support tens of millions of salmon each year. Almost 58 million fish collectively returned to Bristol Bay in 2020, and the salmon run in the Naknek River watershed was exceptional. More than four million sockeye swam up the Naknek River between mid June and late July. The Naknek drainage may have supported the largest single salmon run on Earth this year. About twenty percent of those salmon–maybe 800,000 fish–entered Brooks River.

At Brooks Falls, 747 sat or stood waiting for his meals to come to him. He consistently capitalized on the vulnerability of salmon in the shallow, bubble-filled water. For a winter hibernator like 747, an individual who must eat a year’s worth of food in fewer than six months to survive, efficiency is a valuable trait to express.

Some pundits have called my support for 747 unwavering. Yet, I’m always on the lookout for a better candidate. This year, however, I’ve failed to find evidence of another Fat Bear Week contender that is fatter than 747. Whether you look at fatness as a proportional measure of body size or just through overall size, 747 has both bases covered.

A police department in Colorado even mistook 747 for a large boulder the size of a small boulder.

One person [who I am married to but will go unnamed] has maybe jokingly called me the “worst campaign manager ever,” because my candidate never wins. She might be correct. Despite my prior lobbying efforts, 747 has yet to win Fat Bear Week. Over the last several years, 747 has been snubbed by the voting public who viewed competitors like Otis, Lefty, Beadnose, and Holly as proportionally fatter.

But mark my words, dear readers. This is 747’s year. Cast your Fat Bear Week vote for the bear who shares an identification number with a jet airplane.

GIF of Hulk Hogan and other wrestlers signaling "for life" with hand signals.
Fat Bear Week 2020 bracket. It lists six bears on the left and six on the right. The logos at the bottom represent explore.org, Katmai National Park, and the Katmai Conservancy.
Here are my 2020 Fat Bear Week bracket predictions. Download your own 2020 Fat Bear Week bracket on fatbearweek.org and vote in the tournament from September 30 through October 6. Watch the bears on explore.org.

Early September Bearcam Questions and Answers

This blog has been relatively dark over the last year, not because I hadn’t intended to write for it but because I frequently had other writing duties to fulfill. Afterward completing one task, it was often easier to space out at the end of the day than concentrate on writing something that approaches partial intelligence.

I want to share a little of what I have been writing though. Each Tuesday, I cohost a question and answer session in the comments on explore.org’s Brooks Live Chat channel. It’s an AMA about anything related to Katmai National Park’s bears and salmon. Many people submit your questions in advance, which allows me to answer them with greater detail than a question asked on the spot. Below are my answers to those questions during the Q&As for early September.

Be sure to join the Q&A every Tuesday from 5 -7 p.m. Eastern in the Brooks Live Chat channel, and if you prefer to chat in sentences limited to 200 characters, then join the bearcam conversation on explore.org’s Brooks Falls YouTube feed.

September 1, 2020

I’d like to talk about the “Beaver Pond,” which Kathryn asked about via the Ask Your Bearcam Question form. “I’ve often looked at photos of the [Beaver Pond] and wonder if any salmon can make it to the pond and if any of you have seen bears fishing or hunting around the pond?”

The “Beaver Pond” is located about fourth-tenths of a mile south of the outlet of Brooks River. A road provides an avenue to get near there although there is no developed trail to the pond’s edge. Bears use the area but mostly as part of their efforts to get to and from Brooks River because the pond is inaccessible to salmon.

The Beaver Pond in relation to Brooks River
A beaver at the Beaver Pond

Beavers maintain a lodge on the pond’s north side and a grass-covered dike (an old beaver dam) lines much of that area. But, the Beaver Pond isn’t a true beaver pond in the sense that its formation was the direct result of beavers. It was once part of Naknek Lake and has since been cut off by the sediments deposited by wind driven waves.

The beaver pond was once a cove on the edge of Naknek Lake. Strong easterly winds create waves that erode the gravel shoreline to the southeast of Brooks River. The waves carry gravel and sand northwest toward Brooks River. Over time, a horsetail shaped beach began to encircle the cove.  This image below is from an unpublished geologic report about the Brooks River area. Note the concentric ridges along the lakeshore near the beaver pond. These are the beach ridges that cut off the beaver pond from Naknek Lake.

This process is similar to what we see at the river mouth, especially in the “spit” area that partly encloses a lagoon-like area rangers call the boat cove. The boat cove may be destined to become a small pond or marsh like the wetlands between the river mouth and the beaver pond today, although the mouth of Brooks River is more exposed to direct blows from wind-driven waves than the beaver pond area. Strong storms can quickly rework and reshape the gravel at the river mouth.

In the above image, the parallel lines farther inland are old beaches as well, although they weren’t formed by longshore currents. Instead, they mark the former levels of Naknek Lake and Lake Brooks. Naknek Lake has been slowly lowering in elevation as Naknek River cuts through the glacial sediments that dam the lake.

Although we don’t know exactly what the Brooks River mouth area will look like in the future, we definitely know it will not look the same.

Jen wrote in wondering about the line-up of salmon we sometimes see below the river watch cam and asks, “Has that behavior been noted before?” And, “What criteria initiate egg-laying?”

This is the formation that Jen refers to.

Parallel lines of sockeye salmon in Brooks River. The fish are facing upstream and in this image the current flows from right to left.

Sockeye salmon line up in fairly parallel rows frequently in late summer in the lower Brooks River. Until this year, however, with more salmon using the channel below the river watch cam, we haven’t been able to see this on the cams very well. Although this is not a new phenomenon at the river, I haven’t been able to find an explanation for it. We know the salmon are staging (waiting for the right time to spawn) but I don’t know if lining up in rows gives them any sort of advantage. It may be the most efficient way to sort themselves or there could be some social cue among the fish that prompts the formation. It’s a beautiful feature of the lower river in late summer.

Regarding Jen’s second question, a female salmon lays her eggs in nests she constructs by fanning the gravel with her tail. This action winnows away fine sediments that might hinder water flow (and hence dissolved oxygen) around her eggs. She’s looking for gravel of the right size and in areas of the river with consistent water flow. Males will fan the gravel occasionally too but they play no role in nest construction. Once the female determines her nest is suitable and she’s accompanied by a suitable male, she’ll release her eggs directly into the nest while the male releases his milt. In this way, it is the female who determines when to lay eggs.

LoveTheBears writes, “I understand that there is an area designated for cleaning any caught and kept fish.  What happens with the discarded fish parts?”

There used to be a public fish-cleaning building at Brooks Camp. The first iteration wasn’t much more than screened-in shelter with a bucket on the floor where people disposed fish entrails. It was later replaced by a more substantial log cabin style building where people could clean their fish. Today though, there is no public fish cleaning facilities at Brooks Camp and the public is prohibited from cleaning fish within 1.5 miles of Brooks Falls. People can keep one fish per person per day downstream of the bridge, but they must take it immediately to the Fish Freezing Building (the old fish cleaning building) and place it in a freezer. It must remain there until you depart Brooks Camp.

Although no bears at Brooks River are currently conditioned to seek human food, it hasn’t always been this way. In the 1960s and 1970s, many bears learned to associate people with food and sought opportunities to get at human foods at Brooks Camp. The fish cleaning buildings were part of the issue along with open dumps, outdoor burn barrels for garbage, and overall lack of awareness and regulations about proper food storage in bear country. As part of the effort to reduce the risk of bears becoming food conditioned, the NPS got rid of the public fish cleaning facility.

Bears easily learn and remember any trick that allows them to find food. Therefore, we must remain constantly vigilant to ensure that bears don’t learn to associate us with fish. The NPS and the State of Alaska implemented somewhat strict fishing regulations in the 1990s, which has greatly reduced the number of incidents when bears have learned to associate people with fish. Eliminating public fish cleaning facilities and prohibiting fish cleaning within 1.5 miles of Brooks Falls inconveniences some people but it is a big step toward protecting bears.

September 8

Angela writes, “We were talking about hibernation in the chat thread and wondered if it is necessary for bears to hibernate. We understand that bears at Katmai hibernate, but were wondering if bears in captivity also hibernate or if because there is a regular food source, the need to hibernate isn’t triggered?”

Hibernation exists along a spectrum rather than being an either/or behavior. Some mammals such as arctic ground squirrels are obligate hibernators, meaning they hibernate regardless of ambient temperatures or access to food. Bears experience a type of facultative hibernation. Given the right circumstances, bears needn’t hibernate to survive winter.

Each year, at least some black bears in mild climates (Sierra Nevada foothills, coastal plain of the southeast U.S., and Big Bend National Park to name a few) remain active all year. These are generally adult males. Similarly, a few adult male brown bears are active on Kodiak all year. Mild temperatures and at least some food allow these bears to remain out and about.

In North America, only pregnant female bears must enter a den and it isn’t because they must hibernate. Bear cubs are born so small and physically immature that they need many weeks of additional development before they are mobile enough to travel with mom. This is even true of polar bears who utilize the winter season to hunt seals on sea ice. Instead of heading out on to sea ice in early winter, pregnant female polar bears, just like all other pregnant North American bears, head to dens to give birth.

Although a handful of bears remain active all year, especially in more southerly populations compared to Katmai, hibernation is a bear’s best energy conservation strategy. It makes sense for nearly all bears to hibernate during winter when food is either very limited or non-existent. For those bears who stay active (other than polar bears), their metabolism and activity rates are much lower than summer. Winter activity, therefore, doesn’t mean that bears are as active as they would be in summer. So even captive bears may ignore food and water provided to them, relying more on their hibernative physiology to survive.

Erin asks, “747 is a huge bear. Is he the biggest bear seen at Brooks River? Have there been bigger bears in the past?”

As I’ve said and written many times, 747 is a giant of a bear. He is the most massive bear I’ve ever seen and we should not take his presence for granted. If 747 were to disappear from the river, it may be a long while before we see another as big as he. Last year, 747’s was estimated to weigh more than 1,400 pounds.

747 from Fat Bear Week 2019

Each year, there are comparably sized bears in Katmai and at Brooks River. I’ll start by listing three of the currently seen bears who approach 747’s size class and then highlight two who might have approached it in the past. Only the largest adult males are comparable.

Right now 32 Chunk, 151 Walker, and 856 are close to 747’s size (at least within 300 pounds or so). They certainly rival him when measured by height and length. Each of these bears seem smaller to me than 747, but looks can be deceiving. Size is also an important determinate of dominance in the bear world. It is not absolute though. While 747 is more dominant than Chunk and Walker, 747 consistently yields to 856.

32 Chunk from Fat Bear Week 2019
151 Walker from Fat Bear Week 2019
856 from Fat Bear Week 2018

In the past, Brooks River has hosted some very big bears. While I never had the opportunity to see Diver in person, he was reportedly extremely fat and large in his heyday during the 1980s and 1990s. Look at this photo as an example.

In 2007, the most dominant bear I saw at the river was 24 BB. He was very tall and long–so a massively framed bear. He didn’t use Brooks River in late summer though so we never got to see BB at his peak size for the year. BB behaved much like 856. He asserted his dominance frequently and spent less time fishing than 747 does today, so he might not have been as heavy as 747 but the potential was there.

BB in July 2007

Marlene writes, “856 is getting older. I am wondering if he will know when he no longer can hold the top spot or do you think there will have to be a confrontation?”

856 has been the river’s most consistently dominant bear since 2011. Like all bears, 856 is great at weighing risk versus reward. For him, the overall risk of confronting other bears is low and provides great reward in the form of access to food, fishing spots, and mating opportunities, because other bears recognize his dominance. 856 will use that to his advantage as long as he can.

His high level of dominance is tied to his health and fitness. He’s a large bodied bear so will remain relatively dominant no matter what but he needs to maintain his good health and fitness in case another bear challenges him or is unwilling to yield. 856 might fall from the top of the hierarchy if he is defeated in a fight by another comparably sized bear.

His reign as the river’s most dominant bear could end in another way though. He might not feel up to the challenge.

In July 2017, 856 was an infrequent visitor in July and when he did show up, he yielded easily to 32 Chunk, perhaps because he suffered from a leg injury that hindered his ability to compete with other comparably sized males. At the time, already after many years of dominance, I thought this was the end of 856’s reign at the top. I was wrong. 856 returned to the return to the river in September 2017 looking as healthy as ever and acting as dominant as ever. He hasn’t taken a step back since.

The chances of a repeat of July 2017 could be in 856’s future just as much as his defeat in an intense fight at the paws of another bears. If 856 continues to return to the river as he ages into his early and mid 20s, I think we’ll see at least one of those scenarios play out.

A Step to Protect Brooks River’s Bears

Each year, the National Park Service in Alaska reviews compendiums for park areas and provides the public with an opportunity to comment on proposed changes or suggest changes. This year, Katmai National Park is proposing a change to its compendium that will give staff greater flexibility when managing the Brooks River area. If you value the river’s wildlife and the bear-watching experience at Brooks River, whether in person or through explore.org’s bearcams, then please support this change.

Visitation at Brooks Camp has skyrocketed to unprecedented levels during the last several years. In 2015, the last full summer I spent as a ranger at Brooks Camp, approximately 9,300 people attended the NPS bear orientation. In 2016, the number of orientations climbed to 10,900. By 2018, the number had grown to 12,500 and in 2019 it reached over 14,000, the highest visitation every recorded at Brooks River. This change may not seem like much (Yellowstone’s Old Faithful Visitor Center often receives over 10,000 people per day in summer). However, the Brooks River corridor is quite small. The river itself is only 1.5 miles long and during the busiest days in July over 500 people and a few dozen brown bears attempt to share its space. The increase in visitation and unrestricted access to the river has created an untenable situation that taxes park staff, facilities, the experience, and the bears’ ability to tolerate and adapt.

graph showing number of people attending bear orientations (y axis) by year (x axis). The number of orientations has doubled since the 2000s.

Attendance to mandatory bear safety orientations can be used as a proxy for overall visitation to Brooks Camp. In the last ten years, the number of people attending the orientations has doubled.

Related: Bears and Humans at Brooks River

Brooks River is a unique place within America’s national parks. In a landscape home to more bears than people, it is Katmai National Park’s most famous bear watching destination. However, it is perhaps the only area in Alaska that is actively managed as a bear-viewing destination yet has no restrictions on access. No permits or guides are required to visit. There is no limit to how many people can visit each day and almost no restrictions on where you can go when you get there. Arriving visitors are required to attend a mandatory bear safety talk that outlines the proper and expected behavior. After that though, you are largely free do go about your business. To help manage the situation, the National Park Service has proposed this change to Katmai’s compendium.

The Superintendent may prohibit activities, impose restrictions or require permits within the Brooks Camp Developed Area. Information on closures and restrictions will be available in the park visitor center. Violating [Brooks Camp Developed Area] closures or restrictions is prohibited.

The NPS lists several reasons for the proposed change.

  • High visitation and improper behavior by people has negatively impacted bears along the river corridor.
  • The park has received more complaints and concerns from the public regarding bear-human interactions.
  • Bears are changing how they use the river, so current closures are becoming increasingly inadequate.
  • Visitation has increased dramatically over the last several years.
  • To better manage the river corridor, the park needs more flexible management tools.

While the proposed change is no panacea for the challenges facing park staff at Brooks River, it can provide an important tool to manage changing situations. For example, it hypothetically allows the NPS to extend the closure around Brooks Falls beyond August 15 or even restrict human access in the lower river area when bear activity is high.

Quite often, proposals for greater restrictions and regulations in national parks attract more opposition than support, especially if the change has the potential to impact public access or business interests. Now though, we have the opportunity to let the NPS know this change is worthwhile and necessary.

Portions of Katmai’s bear population are equally sensitive to human disturbance as the grizzlies in Yellowstone, yet the only area in Katmai where people cannot venture is the immediate area surrounding Brooks Falls, and then only from June 15 to August 15. Since I came to discover Brooks River for myself in 2007, protections for bears have slowly eroded. In the face of skyrocketing visitation, the NPS has proposed a positive step to protect bears and the bear-watching experience. So please send the park a comment expressing your support for the change. Here’s an example to get you started (feel free to customize it as you see fit). You can download a copy of the proposed changes and submit comments on the NPS’s project website. The comment period is open through February 15, 2020.

PS: If you plan to visit Brooks Camp this summer or in the future, please consider subscribing to the Brooks River Pledge. It’s a personal pledge between yourself and Brooks River with the goal to emphasize respect for the bears’ space as well as ways to continue to have a high quality bear viewing experience.

Fat Bear Week 2019 Endorsement

Avoiding the news when your job is internet-based is like avoiding the flu when your entire household is infected. So, try as I might, I keep stumbling upon headlines about upcoming presidential primary elections. The big question on the minds of pundits seems to be, “Will people choose the candidate who best represents their values or the one who they think is most electable?”

As a certified bearcam aficionado and well-known Katmai National Park pundit, I am pleased to announce that I have do not have that issue, at least not for the upcoming “election” called Fat Bear Week. My candidate isn’t a compromise between values and electability. He’s the real deal, the one, the only, the titanic bear known as 747. He deserves your vote.

silhouette of fat bear sitting in river

Don’t you call me pudgy, portly, or stout. Just now tell me once again, who’s fat? (NPS photo of bear 747 by N. Boak)

Seven-four-seven is a giant among bears, an adult male in the prime of his life who uses his size to dominate access to his preferred fishing spots in the jacuzzi and the far pool. His experience and skill pay off each fall, supplying 747 with the substantial fat reserves necessary to survive winter hibernation without eating or drinking.

To get this fat, you need to catch and eat a lot of salmon. Adult brown bears on Kodiak Island consume can consume an incredible 6,146 pounds (2,788 kg) of salmon per bear per year! Given 747’s excellent fishing skills and ability to routinely access the most productive fishing locations at Brooks Falls, I have no doubt his salmon consumption is on par with the biggest Kodiak bears. Stuck in his own version of “feed”-back loop, 747 gets fatter and fatter until it’s time to enter the den. (And, no bears probably can’t get too fat.)

If you don’t believe me about 747’s qualifications, believe the Internet, always an impartial repository of truth and honesty. In 2017, I recorded a video of 747 in all his epic fatness. If anything can be gleaned from viewer comments (and of course we know that YouTube comments represent the highest form of public discourse), 747 is an extra THICC absolute unit who is ready to hibernate through two winters.

The people have spoken.

At Brooks Falls, 747 remains quite dominant and can often access any fishing spot he chooses, which is not surprising given his size. Adult males typically rank at the top of the bear hierarchy. Even so, 747 still faces competition, in real life and in Fat Bear Week. This summer, I was awestruck watching 747 clash with another adult male, 68, in an intense fight.

 

Sixty-eight emerged victorious in the battle, not only securing access to a preferred fishing spot at Brooks Falls but also assuring his dominance over 747. Bloodied from the fight, 747 left the falls area almost immediately and I thought I might not see him for the rest of the evening.

bear standing in water with some blood dripping from his lower lip

747 bleeds from the mouth after his fight with 68 on July 2, 2019.

Within an hour or so, he returned and began fishing like nothing happened. When you only have a few months to prepare for winter hibernation, there’s little time to waste.

Like so many things in life, 747’s Fat Bear Week victory is not guaranteed. My 2017 and 2018 endorsements for 747 were followed by his sound defeat. This year, his competition is just as fat if not fatter.

GIF of bear sitting upright and scratching an itch with her left front paw

Dear Holly,

Game on. See you in the Fat Bear Week finale!

Sincerely,
747’s Campaign Manager

Your Fat Bear Week vote can be based on any number of factors. You can consider a bear’s annual overall growth like that experienced by cubs and subadult bears. Perhaps you want to weight your vote toward bears with extenuating circumstances such as a mother’s cost of raising cubs or the additional challenges older bears face as they age. No matter what though, 747 once again offers you, the astute Fat Bear Week voter, the opportunity to support a bear who is both the fattest and the largest, two traits that are not mutually exclusive.

Complete your civic duty and vote for Brooks River’s fattest bear from October 2 – 8 on Katmai National Park and Preserve’s Facebook page. Look for the head-to-head Fat Bear Week matchups. The bear whose photo receives the most “likes” advances to the next round, until one bear is crowned fattest bear on Fat Bear Tuesday, October 8. Don’t forget to watch Katmai’s fattest bears every day on explore.org.

Fat Bear Week 2019 Bracket.jpg

Happy Birthday Bear

Across much of North America, tucked within isolated dens, a new generation of bears is beginning their lives.

Mother bears spent much of the last year preparing for this event. Although the timing varies among species and individuals, North America’s bears mate in late spring and early summer. The fertilized eggs, however, do not immediately implant in the uterus, undergoing only a few cell divisions before they enter a state of arrested development. During this process of delayed implantation, the female goes about her business while embryos remain in suspended animation. Implantation and fetal growth renew only close to the time she enters her winter den. Afterward, bear fetuses gestate for 6 – 8 weeks.

The gestation time is remarkably short for such a large mammal, and it produces especially tiny and helpless cubs. Brown bear cubs, for example, weigh a scant pound and measure only 8 – 9 inches long at birth, about the size of a beagle puppy. They are also born blind, lightly furred, and nearly immobile. Their ears are closed and their muzzles are short with a round, toothless mouth. Newborn cubs are so underdeveloped and small that they cannot maintain their own body heat in the den and must remain in contact with their mother to stay warm. About the only thing they can do is scream, which, not unlike human newborns, they employ frequently to gain their mother’s attention. It’s hard to imagine large adult bears so helpless, but they all start life this way.

Three small cubs held in a person's hands.

Newborn black bear cubs. U.S. Fish and Wildlife Service photo.

The small size of newborn cubs is surprising for animals that weigh several hundred pounds when fully grown. Generally, larger mammal species have longer gestation periods and give birth to larger offspring than smaller mammal species. African elephant calves gestate for nearly two years and are born bigger than elk calves; elk calves gestate for about eight months and are born bigger than deer fawns; deer fawns gestate for seven months and are born bigger than fox kits; etc. But, bears break the rule by a considerable margin. Bears give birth to the smallest offspring in comparison to adult female body size of any mammal.

Cubs are only 1/200th the size of even the smallest reproducing female grizzlies and commonly 1/500th or less for large adult brown and polar bears. In contrast, newborn human babies are an order of magnitude larger than bear cubs. A 10 pound child born from a 150 pound woman is 1/15th the size of its mother (yeah, I know that’s a big baby but the math was easy). Additionally, offspring born to large mammals are generally precocial, i.e. they are at least somewhat and sometimes highly mobile soon after birth. Bear cubs, however, are more akin to helpless hatchling birds or pinky mice. There is no parallel among placental mammals—only marsupials give birth to offspring as undersized as bears.

But why are bear cubs born purposefully premature? Why not just have a longer gestation time and birth larger, more independent cubs? The short gestation period and the relatively small size of bear cubs at birth both appear to be an adaptation to maximize the use of fat.

Bears are the only mammals that give birth while hibernating, a time when they do not eat, drink, urinate, or defecate. Survival during this time is dependent on stored body fat, but the paradigm poses a problem for expectant female bears. A developing mammal fetus cannot metabolize free-fatty acids, perhaps because these substances do not cross the placenta as readily as sugars and protein. So, as long as a bear tries to sustain fetal growth through her placenta, she needs to draw energy from her own body protein. Fetuses also produce bodily waste, which is transferred to the mother and adds to her physiological challenges. To cope, bears evolved an alternative strategy, one that allows her to give birth while hibernating, support the continued growth of cubs, and keep the family safe.

Unlike in the womb, baby mammals can metabolize fat shortly after birth and milk is the vector to deliver it. Bear milk is a particularly rich and nourishing substance. Brown bear milk, for example, is about 22% fat by volume. Polar bear milk is even richer, a whipping cream composed of over 30% fat. By shortening the gestation period, mother bears trade placental nourishment (mostly protein and sugar) for mammary nourishment (mostly fat) and tap into the one resource they have in abundance.

fat brown bear exiting water

Female bears utilize their fat reserves to support the growth and nourishment of their cubs.

On a diet of fatty milk, a brown bear cub can gain about a 1/5 of a pound of body mass per day, weighing about 5 pounds when one month old and 15 – 25 pounds by 90 days. Not coincidentally, this is about big as they would be if gestation was of an “expected” length like other placental mammals. The den, therefore, becomes a surrogate womb, protecting the family during the most vulnerable time in their lives.

Two polar bear cubs standing at the entrance to a snow den.

Polar bears play at the entrance to their mother’s den. These cubs are probably several weeks old. U.S. Fish and Wildlife Service photo.

Bears face many obstacles to survive and reproduce, not the least of which is winter famine. Hibernation provides bears with the ability to outwit winter by surviving on accumulated fat, but during this time a female bear must support the growth of her cubs with nothing more than the energy stored in her body. Given the challenges posed by gestation, hibernation, and winter famine, the birth of a bear represents a remarkable and unparalleled feat of mammalian adaptation.

So, happy birthday brown bear.