While every season has much to admire, I find springtime especially enthralling. Something new appears nearly every day. At first, maple sap runs heavy during March’s warm days and sub-freezing nights. Around then, a trickle of meltwater in a ditch and a bare patch of matted leaves on the edge of a snow bank promise room for other plants to break dormancy. Soon after, the first golden catkins appear on the hazelnut and gray alder. Rainy evenings bring amphibians out of hibernation. In a short time, the soon-to-flower ephemeral herbs emerge from the crust of leaves. By late April and early May, the forest canopy bursts to life again with bird song, the blossoms of red maple and quaking aspen, and finally the unfurling of leaves that will soon thoroughly shade the ground where I trod.
Each of these are little events that promise a lot more. I’m unsure if non-human animals contemplate these changes like I do. Yet, I’m certain they pay attention to them. Black bears, recently emerged from their dens, know the pattern and are eager to exploit the change of the season to their advantage. If I’m lucky, their efforts to find their first substantial meals of the year might allow me to investigate what they are up to.
A section of Katahdin Woods and Waters National Monument sits to the east of Sebois River. It’s a quiet area of the park since there are no campsites, less than a mile of developed hiking trails, and only a few maintained roads. Bicycling through it is fun and is made even more enjoyable when I afford myself the time to go slow and pay attention. It’s one of the best places in park that I’ve yet found to look for bear sign in the spring.
Riding the single lane spur that loops off and back to American Thread Road last weekend I came across many piles of bear scat, which I was hoping to see. Not because I particularly admire turds, but because bears are cryptic here. They are frequently hunted throughout northern Maine and consequently have a substantial fear of people. The thick forest also limits my ability to watch a bear if I happen to see one. The signs that bears leave behind—such as marking trees and scat—are like pages in a book. A single page may not reveal much but look at enough pages and you’ll get a good story.
In particular, scat can reveal how recently a bear was in the vicinity and what it was eating. Black bears are omnivores that are well adapted to survive on plants, and the vast majority of their annual calories come from plant foods. In north-central Maine, though, there are no calorie-rich berries to eat in the spring. Perhaps there are some leftover acorns, but oak trees are not common in the forests as this area is near the northern end of their range in the northeastern U.S. So other plant foods are a bear’s best springtime bet.
While a black bear’s digestive track remains essentially one of a carnivore, it utilizes adaptations such as an elongated gut and slightly flattened molars to extract nutrition from tough to digest plant foods. A bear also consumes plants when they are most nutritious and digestible. Newly emerged green vegetation like grass, sedge, and clover contains relatively high amounts of protein, for example. As those plants mature, protein content declines while indigestible fiber increases. Fiber helps keep the bear on a so-called regular schedule, but the bear is really after the protein. Even though hibernating bears maintain their muscle health without eating or exercise, if they’ve exhausted their fat reserves by springtime then their body is forced to tap into their lean tissue reserves. Young, tender veg helps bears stave off muscle loss and even build muscle before sugary, fat-building foods become available in mid to late summer.
All but one of the scat piles I found were filled with herbaceous plants. Although most looked older than a day–when bears eat green veg, the resulting scat quickly oxidizes when exposed to air to form a black surface crust–this was a promising sign. I knew that the lightly used roads are good travel corridors for bears and the sunlight reaching the road edges allows vegetation to green-up more quickly than the forest interior, which attracts bears to the roadsides. Perhaps I might see a bear if I pedaled slowly and remained observant.
The effort paid off near the crest of a hill when I spotted a dark mass of animal on the edge of the road. I stopped to watch.
The wind was at my back, which is a welcome push when cycling uphill but also carried my scent to the bear. Once it caught my scent, the bear only needed a couple of seconds to decide to run into the forest. Had the wind been blowing the other way, I probably could’ve watched it much longer with less chance of disturbing it unintentionally. Still, I was grateful for the moment and the small insights into its world.
Before widespread logging and, later, roadbuilding encroached on the area’s forests, grassy areas in northern Maine were likely much less common than today. Black bears always sought the first spring greens, but they had to look in other places—riverbanks, stream sides, and beaver meadows for example. They continue to go to those areas, of course, even as roadsides have opened another foraging opportunity. Roads are risky places that expose bears to people though. Bears weigh the risk along with the potential reward of a good meal.
I knew the bear I saw was eating well even as it still had a long way to go until it was fat enough to enter its winter den next fall. Its effort is a journey recorded in its scat—pages, if you will, in the Book of Turds.
Brooks River in Katmai National Park, Alaska is historically, culturally, and ecologically unique. The river corridor has harbored Alaska Native peoples for thousands of years, is one of the densest archeological sites in Alaska, and remains a place of profound significance for Alutiiq descendants of former Katmai residents. The underlying geology records stories of great volcanic and glacial change. Hundreds of thousands of sockeye salmon annually use the river for migration and spawning. And, during the last 40 years it has become especially famous for its brown bears and wildlife viewing opportunities. There’s no other place like it.
Brooks Camp is also experiencing more people than ever before.
In the midst of skyrocketing visitation last year, Katmai National Park implemented a pilot permit program for Brooks River. The permit system didn’t change wildlife distance regulations at Brooks River or limit the overall number of people who could visit. Instead, it applied only to those who wish to physically enter the river or its banks outside of the designated trails, roadways, bridge, and platforms. No one needed to reserve a permit unless they planned to enter the river or walk off trail along the riverbanks (two activities that I suggest should be avoided to give bears the space they need).
The pilot program appeared to be successful. It provided National Park Service (NPS) staff with an additional opportunity to communicate the special circumstances, rules, and responsibilities that apply to Brooks River. The NPS could revoke the permit in instances where permit holders did not adhere to wildlife distance or fishing regulations, which effectively prohibited the person(s) from reentering the river. It allowed approved Brooks River Guides to continue to give their clients the mandatory bear-safety orientations. And finally, it did not restrict or interfere with subsistence fishing associated with the traditional redfish harvest.
Why are permits necessary? The relative ease and accessibility of the bear-viewing experience at Brooks Camp has attracted increasing numbers of people. More than 16,000 people visited in 2022—an all time record high—and almost double the visitation of 2008. Brooks River is a mere 1.5 miles (2.6 km) long, yet dozens of brown bears use it during the salmon migration and spawning seasons of summer and early fall.
People who enter in the river directly occupy the habitat that bears need to fish for salmon. Numerous scientific studies (reviewed here) have documented that human recreation can displace bears in time and space. The presence of people can cause bears to switch from diurnal to crepuscular activities in response to bear-viewing, angling, hiking, and camping. Bears decrease in number and are present for shorter time spans when exposed to people, angling, and bear-viewing. Bears also spend less time fishing and have less fishing success when anglers and bear-viewers are present.
Studies specific to Katmai National Park have found that the presence of people can affect when bears fish (Olson et al. 1998) and cause bears to avoid or alter their use of foraging areas (Rode et al. 2007; Smith 2002; Turner and Hamon 2016). Therefore, even a small number of well-behaved and well-intentioned people in the wrong place (like in the river) can have a disproportionately negative effect on brown bears. Disturbance of wildlife can also result in decreased visitor satisfaction (Skibins et al. 2012) and create user conflicts between visitors who are recreating in different ways (bear watching from the platforms or online via webcams vs fishing or photographing bears in the river).
Importantly, and tucked away in the park’s newsletter about the permits, is this: “There is no limit established to the number of permits issued during the permit-required time frame currently, but this will be considered if public feedback to the plan supports a limitation or if conditions change within the Brooks River Corridor to warrant a limitation.” Therefore, I recommend that comments ask the NPS to go beyond merely requiring permits. Comments about the permits should encourage the NPS to establish limits to permits on a daily or weekly basis and perhaps even greater seasonal closures to Brooks River to adequately protect habitat for bears.
I didn’t visit Brooks River in person last year, but rangers and some people I know who had traveled there reported to me that the pilot permit system worked well. While it does not address over-crowding and congestion issues at Brooks Camp caused by record-high levels of visitation, it is certainly a big step in the right direction to ensure the river’s bears have access to the habitat they need to survive. None of the existing regulations would change at Brooks Camp. The permits only make it easier for the NPS to enforce them. But permits alone are not enough. Existing protections for bears can be made more effective if permits were limited in availability. Our national parks, and indeed Brooks Camp, cannot support unlimited numbers of people. The Brooks River corridor is a small area overall. It has limited space for bears and a limited carrying capacity for a high-quality bear-viewing or fishing experiences. Please let the NPS know you support their efforts to protect habitat for bears in the river through the permit system and that the number of permits should be limited on a daily or weekly basis when bears are actively fishing in the river.
This may seem non-controversial. After all, wild animal populations are made of individuals just like human families and communities are composed of individual people. But this idea hasn’t been accepted widely among scientists and managers of national parks.
Thankfully that tide seems to be turning, and I’m pleased to be able to contribute to this scientific effort. Results from a survey of bear cam viewers on explore.org show that people who care about Otis and other individual bears are more likely support conservation efforts for brown bears compared to viewers who do said they could not identify individual bears. Please head over to my post on explore.org to learn more.
I’d like to thank the researchers who made this study possible—Jeff Skibins (who drafted this paper and did the data analysis) and Lynne Lewis and Leslie Richardson (who were instrumental in the survey design and implementation). I’d also like to thank the Katmai Conservancy for covering the expense to make the paper available to everyone through open access.
Last summer, explore.org celebrated the 10th anniversary of the bear cams at Brooks River in Katmai National Park. These webcams offer an in-depth look at the behavior and ecology of a population of brown bears, allow us to observe the same individual bears over many years–giving us the chance to learn about their personalities and habits–and provide a platform for rangers and other experts to host live programs and commentary about the bears and their stories. It’s a wildlife watching experience like no other.
As part of the celebration, I chose to highlight some the moments that I thought were most memorable from the last ten years of bear cam. Some explore point-in-time events. Others celebrate the behavior of individual bears who have left their mark on Brooks River in ways we can’t forget or ignore. Each was unforgettable from my perspective. I hope you enjoy them.
Most Defensive Mother: 128 Grazer
Grazer is an archetypal mother bear. Don’t get in her way and don’t approach her cubs.
Lefty Learns to Fish at Brooks Falls
Old bears can definitely learn new tricks. In July 2015, we watched a fully mature adult male brown bear figure out how to fish where he’d never fished before.
Otis Eats 42 Salmon in a Sitting
Be awed by the capacity of his stomach.
Death of 451’s Spring Cub
When a bear cub falls ill the world will watch.
A lone yearling finds a new family.
Reign of 856
Few bears will ever experience the prolonged dominance and advantage earned by 856.
2020 Salmon Smorgasbord
What happens when bears have access to unlimited salmon? The 2020 salmon run gave us the answer.
History of Fat Bear Week
A goofy idea becomes a world famous internet sensation.
We are Family: 909, 910, and Cubs
Sister bears reunite while raising cubs to create an extended family.
If that’s not enough, the bear cam community complied links to all of our bear cam live events from 2022. Two stand out in my mind: 1. The impromptu Q&A about a fight between and mother bear and a dominant male, and 2. The bear cam 10th anniversary live chat.
We’ve seen a lot of special moments on the cams during the last ten summers–perhaps too many to recall–so these are only a small snippet of the larger story. What are your most memorable moments from the bear cams?
As is tradition—going way back to the before times (2017)—I’ve endorsed a bear for Fat Bear Week. This year’s bracket might be difficult to predict, but with voting commencing today at 12 p.m. Eastern and continuing through October 11, it’s time to throw my weight behind a Fat Bear Week contender.
I’d let him speak for himself but his mouth is usually too full of salmon.
Friends, humans, and ursids, let us stand in awe of a true competitor. A candidate with conviction. A candidate with strength. A candidate that stands up for what he believes. A candidate the size of a double-wide refrigerator. This Fat Bear Week vote for the mighty 747.
747 returns to Brooks River every summer as a giant and just keeps getting bigger.
Perhaps you don’t want to listen to me. After all, I’ve endorsed 747 before and it hasn’t usually led to his victory. Our culture is celebrity obsessed, though, so maybe you’ll listen the expert opinions of these randos.
Homer remarked that 747 is the only other individual whose blubber flies like his.
Pee Wee Herman agreed that 747 was the fattest bear, but he was incredulous when Amazing Larry said he might vote for another candidate.
Dr. Evil threatened world destruction if 747 fails to win.
I spoke with the President too, believe it or not. (He seems to clear his schedule when you have something to say about Fat Bear Week.) Joe Biden noted that 747 grew proportionally faster than this year’s inflation rate.
747’s summer was one of competition and success. In June and July, he yielded space to bear 856. By August, however, 747 turned the tables. He frequently challenged and displaced his long-time rival.
It’s hard work staying dominant and getting fat too. Bears as large as 747 tend to overheat easily, and while their limb bones are built to support their great mass sometimes climbing those hills is a struggle.
You also can’t get that fat without eating a lot of food, and 747 excels in this life goal. Although we don’t know exactly how many fish 747 ate this year, a study about brown bears on Kodiak Island may provide some insight.
Brown bears shed their fur once per year in early to mid summer. Since new fur grows during a bear’s active season, it contains a record of what the bear ate during that time. Studies of captive bears had previously determined the relationship between the mercury content in food and the mercury content in hair. To apply this to bears on Kodiak, researchers first determined how much mercury is found in the Pacific salmon that spawn on Kodiak. They then analyzed the mercury content found in the bears’ hair to gain an estimate of salmon consumption. Large adult males, on average, ate 6,146 pounds (2,788 kg) per bear per year! Some adult males ate a lot more, though, as much as 10,000 pounds of salmon. Since 747 fished at Brooks Falls almost every day between late June and mid September this summer, then his total salmon consumption may likely have been near the upper end of that spectrum.
For fisheries managers and biologists, these statistics are more than pieces of trivia. They are necessary to help inform decisions about salmon escapement goals, so that salmon runs are sustainable for people and the wildlife who depend on them. The aforementioned Kodiak study found that “the estimated population of 2,300 subadult and adult bears [on Kodiak] consumed 3.77 million kg of salmon annually, a mass equal to ~6 percent of the combined escapement and commercial [salmon] harvest (57.6 million kg).” Katmai National Park’s bear population is about as large as Kodiak’s, and when we work to sustain salmon runs we’re also celebrating the life they provide to many other species and individuals, such as bear 747.
Bears get fat to survive winter hibernation, and Katmai National Park’s Fat Bear Week bears are well positioned to weather the oncoming famine. But there’s candidate who eclipses the rest. Your bear might be a 10 but 747 is 1,400 pounds. I’m voting for 747, are you?
Download your bracket from FatBearWeek.org and go there to vote in each Fat Bear Week match from October 5 to 11.
THE THING ABOUT BEARS IS THAT A LOT OF THEM ARE BIG. BUT LIKE HAVE YOU SEEN 747?? HE’S SO BIG. A GIANT, REALLY. HE JUST SITS THERE AND FISHES LIKE THERE’S NO TOMORROW. I MEAN HE HARDLY LEFT THE FALLS ALL SUMMER. DOESN’T MATTER HOW COLD THE WATER IS OR WHICH OTHER BEARS ARE THERE….
Life as a champ is rough. Rivals look to take advantage of any weakness you might show. Arm chair critics analyze your every move. Fans expect perfection. When the next championship tournament rolls into town your body has aged another year and your preferred food has worked its hardest to evade and escape you. Meanwhile, you’re trying to live your best life, because you are a bear and the concerns of humans matter not to you.
Yet, for those of us who recognize greatness and celebrate success when we see it, there is one clear choice for Fat Bear Week 2021—the mighty 747.
Long-time readers of this blog may be thinking, “This again?”
…Let me tell you dear friends: 747 is as fat as ever. He deserves your Fat Bear Week vote.
Brown bears get fat to survive. Their obesity (and it is that since a bear’s body fat percentage is routinely 20-30 percent or more when they begin hibernation) is a savings account. In the den, bears do not eat or drink. They stay warm and hydrated by burning body fat. Unlike utilizing muscle for energy—a process that produces metabolic wastes that must be recycled, sequestered, or purged from the body—burning fat is a relatively clean fuel as I write in chapter 4 of my book, The Bears of Brooks Falls.
It’s akin to cultivating mass only to carefully harvest it later. Just not for vanity’s sake, bro.
747 cultivates mass at an exceptional rate. This summer, he reigned as Brooks River’s most dominant adult male. Even the river’s long-time dominant bear, 856, would not challenge him, and as a result 747 had nearly free access to any fishing spot of his desire.
A single brown bear can eat thousands of pounds of salmon per year. The largest can eat 6,000 to 10,000 pounds. Given his size, appetite, high rank in the bear hierarchy, and his keen fishing skills, 747 is more than capable of eating many thousands of pounds of salmon each summer. At Brooks Falls, he intercepts a great deal of fish by being at the right place at the right time and waiting for his food to come to him. When Brooks River’s sockeye migrated upstream, 747 was primed to harvest them.
He’s so successful that in September 2019 and again in September 2020, he was estimated to weigh more than 1,400 pounds. This places him, as I estimate, among the top one percent of brown bears based on body mass.
Even with his size, he remains agile.
Well, maybe not always that agile.
When he walks close to the webcams at Brooks River, he eclipses the sun.
And yes, that is a tapeworm hanging on for a ride.
Fat Bear Week celebrates the success of Brooks River’s bears, the ecosystem and salmon that sustain them, and the bears’ abilities to get fat and survive. 747 exemplifies success among adult male brown bears. He deserves your vote and a repeat Fat Bear Week victory.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.