brown bears

2020 Fat Bear Week Endorsement

/ Mike Fitz / 10 Comments

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

/ Mike Fitz / 3 Comments

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

/ Mike Fitz / 21 Comments

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.

My Live Bearcam Broadcasts in 2018

/ Mike Fitz / 2 Comments

This was a busy year on the bearcams, courtesy of explore.org and Katmai National Park. We hosted more live broadcasts this  year than any other year since the bearcams first went live in 2012.

During play-by-play broadcasts Katmai rangers and myself narrated the Brooks River’s wildlife activity, much like broadcasters for sporting event (although the lives of brown bears and salmon is no game). We never knew what might happen during a play-by-play. Watching the prolonged posturing between two of Brooks River’s largest adult males, 856 and 32 Chunk, on July 12 and integrating the ranger’s radio traffic into the September 17th broadcast are two of my favorite play-by-play moments.

The other broadcasts, live chats, typically focused on a specific topic such as bear fishing styles, hibernation, and bear research at Brooks River. Rangers Andrew LaValle and Russ Taylor from Katmai joined me as frequent co-hosts for live chats and I was also fortunate enough to speak with many special guests. Perhaps the most memorable moment from these broadcasts occurred when bear 132 and her spring cub almost stepped on Ranger Andrew and I during our Katmai centennial live chat on September 24.

If you enjoy these, then please watch many other broadcasts hosted by Katmai National Park rangers and staff on explore.org’s education channel on YouTube.

 

Fat Bear Week 2018 Endorsement

/ Mike Fitz / 16 Comments

Last October I wrote, “There are small and fat bears, old and fat bears, young and fat bears, and just plain fat bears. But none, NONE I say, are as fat as 747.” A year later, 747 continues to demonstrate his survival skills and success at Brooks River. He’s big enough and fat enough to once again earn my official endorsement for Fat Bear Week 2018. 747 is titanic, a giant among bears.

GIF of large, dark brown bear walking down a steep hill

Bear 747 is an adult male in the prime of his life. First identified as a subadult bear in 2004, he’s matured into the largest bear I’ve ever seen.

 

747 on July 5, 2018.
747 on September 10, 2018.

But don’t just take my word for it. Bear 747 is endorsed by several of his competitors at Brooks River.

bear lying on ground

“Look, we’re all fat right now, but no one is as fat as 747. Seriously, his belly nearly drags on the ground. Even I never achieved that level of pudge. “ Bear 410

profile of bear walking along edge of river

“I keep my distance from him because I’m concerned he’ll roll on top of me.” Bear 68

402_07062016

“I’m still in awe of his size. Can he even dig a den big enough to fit within?” Bear 402.

bear with blond ears and blond coat standing in water

“Even though I’m in the Fat Bear Week bracket, I still might vote for 747. It’s the logical vote. He probably weighs at least three times as much as me.” Bear 719

profile of brown bear standing on edge of waterfall

“747 is a role model of fat bear success. I hope to be as fat as him one day.” Bear 503

bear sitting in water below waterfall

“I’m too hungry to comment.” Bear 480 Otis.

Many people who have observed 747 closely also agree with the endorsement.

bear lying in water facing photographer

“He’s all business—fishing and eating. Nobody gets fat like 747.” Jeanne R., former Katmai National Park ranger.

Too much fat is unhealthy for humans, but fat is essential to the survival of brown bears. It is a savings account against famine. Without ample fat, bears do not survive hibernation. In spring, often a season of starvation for bears, females with cubs will metabolize fat into milk to nurse their growing cubs, and adult males will use their fat to fuel their pursuit of mates.

747 won’t be rearing any cubs next spring as male brown bears play no role in raising offspring. During a season when almost no high calorie foods are available to bears, 747 will use his fat to roam the landscape for mates instead.

Other bears might be more charismatic or tug on your heartstrings, but 747 truly is a giant among Brooks River bears. He deserves your vote for Fat Bear Week 2018.

Katmai Fat Bear Week Bracket 2018 Fitz choices.png

My 2018 Fat Bear Week bracket predictions.

You are encouraged to vote for Brooks River’s fattest bear on Katmai National Park and Preserve’s Facebook page. Starting on Oct. 3, park rangers will post head-to-head matchups between well-known bearcam bears. The bear whose photo receives the most likes will advance to the next round, until one bear is crowned fattest bear on Fat Bear Tuesday, October 9th. Don’t forget to watch Katmai’s fattest bears on bearcam.

 

 

 

Return to Bearcam 2018

/ Mike Fitz / 14 Comments

As many readers of this blog are aware, one of my favorite places in the world is Brooks River in Katmai National Park. There, about 300 miles southwest of Anchorage, Alaska, brown bears and salmon gather to create one of the most iconic scenes in America’s national parks.

many bears standing and fishing near a waterfall

Brooks Falls on a busy evening

 

I’m pleased to announce that through the generosity of explore.org, I’ve received a fellowship to work with Katmai’s bearcams, live streaming webcams of at Brooks River.

In conjunction with Katmai’s park rangers, I’ll write blog posts (which you can read on explore.org and Medium), chat frequently in the bearcam comments, and host live chats and play-by-play style broadcasts. I hope to make time to write about my other explorations on this blog as well.

Bearcam season is almost upon us. Webcam technicians are at Brooks River now, upgrading the webcams for a better live cam streaming experience. The first sockeye salmon should arrive at Brooks River in a matter of days and the bears will arrive soon after. This will be an exciting summer, so please join me here and on bearcam.

The Difference Between Brown and Grizzly Bears

/ Mike Fitz / 5 Comments

For my book on Brooks River’s bears and salmon, I find myself digging deep into natural history and ecology of brown bears. Sometimes I uncover research that challenges my long held assumptions. Take the difference between brown and grizzly bears, for example; something I often said was mostly based on geography and diet. As I wrote for Katmai’s website:

All grizzly bears are brown bears , but not all brown bears are grizzly bears. Grizzly bears and brown bears are the same species (Ursus arctos), but grizzly bears are currently considered to be a separate subspecies (U. a. horribilis). Due to a few morphological differences, Kodiak bears are also considered to be a distinct subspecies of brown bear (U. a. middendorffi), but are very similar to Katmai’s brown bears in diet and habits.

Even though grizzlies are considered to be a subspecies of brown bear, the difference between a grizzly bear and a brown bear is fairly arbitrary. In North America, brown bears are generally considered to be those of the species that have access to coastal food resources like salmon. Grizzly bears live further inland and typically do not have access to marine-derived food resources.

These geographic and dietary distinctions seem simple enough. However, there is little scientific evidence to support it. Both brown bears and grizzly bears exist, but the differences between them aren’t what I had long assumed.

bear grazing on vegetation with travertine and forest in background

A grizzly bear grazes on springtime vegetation near Old Faithful in Yellowstone National Park.

bear in water

A brown bear at Brooks Falls in Katmai National Park. (NPS Photo)

Although North American brown, grizzly, and Kodiak bears belong to the same species, Ursus arctos, bear taxonomy underwent many revisions before scientists reached this conclusion. In the nineteenth and twentieth centuries, taxonomists frequently lumped and split brown/grizzly bears into many different species and subspecies. The separation peaked in 1918 with the publication of C. Hart Merriam’s Review of the Grizzly and Big Brown Bears of North America in which Merriam proposed around 80 (not a typo) species and subspecies of North American brown bears. Taxonomists like Merriam relied on morphological characteristics that could be seen or observed to classify living and extinct organisms. Warm-blooded animals that have hair, breathe air, and produce milk for their offspring are mammals, but warm-blooded and air-breathing animals that lay eggs, have feathers and toothless beaks are birds. These are greatly simplified examples, I realize, and such tidy and clear distinctions aren’t necessarily common in nature. They often become more difficult to resolve at the genetic and species level, especially in cases of hybridization or when taxonomic distinctiveness is based on subtle physical differences.

Merriam’s nuanced classifications of brown and grizzly bears were based on differences in skull morphology and dentition, characteristics he examined painstaking detail. Among taxonomists, Merriam was a splitter. On southeast Alaska’s Admiralty Island alone, he classified five distinct species . In the Katmai region, Merriam described two species, Ursus gyas for the Alaska Peninsula and Ursus middendorffi for Kodiak Island , as well as others for bears living in the Cook Inlet area and on the Kenai Peninsula.

If you think his classifications of brown/grizzly bears was a little over the top, you’re not alone. Merriam foreshadowed opposition to his conclusions when he wrote in his Review, “The number of species here given will appear to many as preposterous . To all such I extend a cordial invitation to . . . see for themselves.” And they did. Most of the species or subspecies described by Merriam were later regarded as local variations or individual variants. While all of Merriam’s species have since been lumped together as U. arctos, in the mid 1980s as many as nine extant or extinct subspecies of U. arctos were recognized in North America , but the only names for North American brown bear subspecies in still widely used are U. a. horribilis, the grizzly bear, and U. a. middendorffi, the Kodiak bear. Recently, however, even these classifications have come under question.

In hindsight, it’s easy to scoff at Merriam’s conclusions. Could there really be dozens of brown bear species in North America? Within the methodologies and knowledge of his era, his results aren’t that far fetched. Little was known about the behavior, growth rates, ecology, and population dynamics of North American bears in the nineteenth and early twentieth centuries. Given access to the same tools and information as modern taxonomists, Merriam may have discovered grizzly and brown bears can’t be so easily divided by differences in skull and tooth shape.

Ursus arctos is one of the most widely distributed mammal species on Earth. Historically, brown bears were found from the British Isles south to North Africa and east across northern and central Asia to Alaska and most of western and central North America. Two to three million years ago, they split from a common ancestor shared with black bears . The oldest brown bear fossils are from China and date to about 500,000 years ago. By 250,000 years ago, they spread to Europe. During the last 100,000 years of the Pleistocene, bears immigrated and emigrated across much of the northern hemisphere as climate and habitat dictated. When continental ice sheets advanced, available habitat shrunk and bears became isolated into separate populations. When the ice receded, bears dispersed into the new territory. Beginning around 70,000 years ago, the first brown bears moved into North America. While we know when and where bears lived and live from fossils and historical records, this doesn’t necessarily deduce the genetic relatedness of modern populations.

Phylogeography is a branch of phylogeny, the evolution of an organism or group of related species or populations. As such, phylogeography traces the distribution of genetic variation through time and space. In this regard, mitochondrial DNA (mtDNA) is especially useful to track female ancestry. MtDNA  resides in the mitochondrion, a cell’s powerhouse, and is inherited from the mother only, unlike nuclear DNA which is a recombination of genes from both parents. According to mtDNA analysis, there is no divide between brown and grizzly bears based on an animal’s relationship to the coast or marine food sources, nor does it support the status of U. a. horribilis or U. a. middendorffi or any other historical subspecies in North America. The only historic classification that holds is at the species level—Ursus arctos. Instead, matrilineal ancestry suggests brown bears in North America fall into three main clades.

  • Mainland Alaska, Kodiak Archipelago, and northwest Canada.
  • ABC Islands (Admiralty, Baranof, and Chichagof) in southeast Alaska.
  • Southwestern Canada (Alberta, British Columbia) and the lower 48 States.

Clades are groups of organisms evolved from a common ancestor and consequently share a genetic relationship. The three North American clades, as well as others in Europe and Asia, are believed to be descended from brown bears living in isolated populations in Asia during the late Pleistocene . Since then, the mtDNA has remained geographically separated due to the tendency of female brown bears to be homebodies. Female brown bears are philopatric. They tend to remain near or have partly overlapping home ranges with their mother and do not rapidly invade areas already occupied by other brown bears . This can prevent or at least greatly slow mtDNA from mixing into other bear populations, even long after significant barriers like ice sheets have disappeared.

screen capture of Earth with clades of bears outlined.

Approximate range of brown bear clades in North America based on mtDNA. Different clades are represented by horizontal and vertical lines. The solid red circle marks the location of brown bears on the ABC islands.

Bears on the ABC Islands are the most genetically distinct of all Ursus arctos. Their mtDNA aligns them more closely to polar bears than to other brown bears , a genetic uniqueness most likely resulting from interbreeding with a small number of isolated polar bears at the end of the last ice age. Since then, female brown bears on the islands have not spread their polar bear genes to the mainland. Bears in British Columbia, Alberta, and into the lower 48 represent another lineage who arrived in Alaska around the same time as the ancestors of the ABC bears. During a warm interglacial period, some of these bears moved south into the mid continent before the ice advanced again and sealed them off from their brethren to the north.

All other brown bears in northwest Canada and Alaska, including those on Kodiak, belong to a clade that dispersed from Asia in two separate waves. Those in northwest Canada arrived first, perhaps as early as 33,000 years ago. Bears now occupying mainland Alaska represent the last pulse of ursine migrants onto the continent, arriving just before rising sea levels flooded the Bering Strait and closed the land bridge between Asia and North America. Excluding the ABC islands, all Alaskan brown bears belong to this pedigree, which stretches from northwestern Canada and Alaska west across Russia and into Europe and includes most of the world’s brown bears.

The results from mtDNA only convey information about the maternal line, however. MtDNA cannot trace genes spread exclusively by male brown bears, so it underrepresents the role of males in gene flow. Male brown bears have larger home ranges and disperse away from their mother’s home range more readily than females, especially during their first few years of independence. Males do carry one important bit of DNA that females don’t—the Y chromosome. Like mtDNA, it is only inherited from one parent, but unlike mtDNA it can only be passed from father to son, making the Y chromosome an important marker to trace paternal gene flow and diversity.

While mtDNA shows particularly strong clade differentiation  across the entire range of Ursus arctos, geographic variation in the Y chromosome of brown bears is much shallower . According to analysis of the Y chromosome, no deep genetic or geographical divergences could be found from bears in Eurasia or North America. Brown bears on the ABC islands and mainland Alaska, for example, share closely related haplotypes (a group of genes inherited from a single parent ) found in the Y chromosome. Even brown bears from populations as separate as Norway and the ABC islands have been reported to carry highly similar Y chromosomes . Male genes, therefore, flow across clades.

infographic showing hypothetical inheritance of mitochondrial DNA and Y-chromosome through three generations of bears.

Within mammals, mitochondrial DNA can only be inherited through the maternal line. The Y chromosome is only passed from father to son. MtDNA tends to stay within genetically related clades because female bears are philopatric. Male bears, due to their inclination to disperse farther and have larger home ranges than females, can spread Y chromosomes over bigger areas. Unlike nuclear DNA, neither mtDNA nor the Y chromosome are a mix of maternal and paternal genes.

This isn’t to imply male bears from the Yukon immigrate to Europe or vice versa, just that males are more apt to wander and set up home ranges well away from their mother. If female brown bears, due to their philopatry, differentiate a population’s genetics over time, then male bears homogenize it. In other words, female brown bears like to stay in familiar terrain, but males often spread their seed far and wide.

With evidence of geographically isolated clades through mtDNA but not in the Y chromosome—can we still divide brown bears into biologically significant units? Even though genetic research adds another dimension to our understanding of wildlife, morphology remains an important way to differentiate species, and subspecies don’t necessarily need to be from separate or unique ancestry to be worth protecting. Grizzly and brown bears still exist, just not along a clean geographic and dietary divide. Where we draw the line is less important than the overall conservation of bears. Populations of brown bears—whether they are from Katmai, Kodiak, or Yellowstone—remain ecologically and culturally special no matter their genetic distinctiveness. Bears in Yellowstone are geographically and (at least currently) genetically separated from other “grizzlies.” Kodiak bears aren’t genetically distinct enough to justify them as a separate clade even though they have been isolated from mainland bears for approximately 12,000 years. Hypothetically speaking, if bears are extirpated from Kodiak or Yellowstone then they won’t be coming back and a valuable repository of genetic diversity will be lost forever.

The line between a brown bear and a grizzly, as I used to define it, was always tenuous at best. (Should grizzlies in interior Washington, British Columbia, and Idaho—who may have fed on salmon before runs in the Columbia and Snake watersheds collapsed—be considered brown bears?) Now through DNA analysis we know Ursus arctos cannot be so arbitrarily split based on their geographical closeness to the ocean. It’s still ok to say grizzly, Kodiak, or brown bear—the names can still be incredibly powerful and useful—but maybe the only truly accurate name for them is Ursus arctos.

References:

Bidon, T. , et al. Brown and polar bear Y chromosomes reveal extensive male-biased gene flow within brother lineages. Mol. Biol. Evol. 2014. 31(6): 1353-1363.

Davidson, J., et al. Late-Quaternary biogeographic scenarios for the brown bear (Ursus arctos), a wild mammal model species. Quaternary Science Reviews. 2011. 30:418-430.

Rausch, R. L. Geographic Variation in size in North American brown bears, Ursus arctos L., as indicated by condylobasal length. Canadian Journal of Zoology. 1963. 41(1): 33-45.

Schwartz, C.C. et al. “Grizzly Bear,” in Wild Mammals of North America: Biology, Management, and Conservation. 2nd Edition. Editors Feldhamer, George A., Bruce C. Thompson, and Joseph A. Chapman. John Hopkins University Press. 2003.

Talbot S. L., et al. Genetic characterization of brown bears on the Kodiak Archipelago. Final Report to Kodiak National Wildife Refuge, U.S. Fish and Wildlife Service. 2006.

Waits L. P., et al. “Genetics of the bears of the world.” In Bears: Status Survey and Conservation Action Plan. Compiled by Christopher Servheen, Stephen Herrero, and Bernard Peyton. IUCN/SSC. 1999.

Waits, L. P., et al. Mitochondrial DNA Phylogeography of the North American Brown Bear and Implications for Conservation. Conservation Biology. 1998. 12(2): 408-417.

 

Drivers of Hibernation

/ Mike Fitz / 10 Comments

Brown and black bears hibernate to avoid winter famine. For five to seven months, they do not eat, drink, urinate, or defecate, a strategy quite unlike other mammalian hibernators. Chipmunks, for example, cache food to eat in between bouts of torpor. Marmots and arctic ground squirrels don’t eat during winter and survive off of their fat stores like bears, but they activate their metabolism periodically to wake and urinate.

I recently spent about 40 hours reviewing studies related to hibernation and denning in brown bears for a chapter in my book on Brooks River’s bears and salmon, which reminded me just how remarkable this process is. While in the den, bears spend about 98% of their time not moving. Their heart rate declines dramatically from 50-60 beats per minute during summer to 10-20 per minute in hibernation. During this time, they hardly breathe, taking 1.5 breaths per minute on average. Their body temperature drops several degrees entering them into a state of hypothermia. Finally, the metabolic rate of a hibernating bear is 70-75% less than its summer peak. To survive, bears subsist on their body fat, catabolizing it into energy and water.

brown bear sitting on rock surrounded by water

All brown bears, like this adult male known as 89 Backpack, get fat to survive.

Despite their lack of physical activity, hibernating bears maintain muscle strength and bone health. Even if immobilization didn’t cause starvation, osteoporosis, and atrophy in people, we would die of dehydration if placed in an equivalent situation. Hibernating bears, however, are nearly completely self-supporting. The only input they need from the outside world during hibernation is oxygen.

The physiology of bear hibernation is complicated and not fully understood. Scientists are still elucidating basic details about this remarkable process. For example, what causes bears to enter and exit the den? How long do bears need to switch their metabolism from to hibernating mode? As it turns out, the switch is a long process.

Researchers in Sweden used implanted heart rate monitors and GPS-enabled tracking collars on fourteen brown bears. The devices recorded the movement, heart rate, heart rate variability, and body temperature as well as ambient temperature and snow depth. The results, published last year in “Drivers of hibernation in the brown bear,” are insightful because it allowed the researchers to develop correlations between the variables that drive and trigger hibernation.

In fall, well before hibernation begins, body temperature and heart rate of bears began to decrease. Heart rate started to slow, on average, 24 days before den entry, and body temperature began to drop 13 days before den entry. Overall activity lessened 25 days before entry, but metabolic activity declined steeply just as the bears entered their dens. It took an additional 20 days after for heart rate and metabolic activity to bottom out.

The transition back to a more active physiology started long before bears left their dens. Heart and metabolic rate began to rise one month and 20 days, respectively, before den exit. Body temperature began to rise even earlier, a full two months before den exit when winter still locked the landscape in ice and snow. All bears left the den when their body temperature was 36.7˚C (98˚F) ± 0.15 °C, the active-state body temperature for brown bears. As the researchers note, the narrow temperature range at this time suggests bears exit the den when their body temperature reaches a specific point. Body temperature and metabolic rate stabilized 10 and 15 days, respectively, after den exit, but heart rate didn’t stabilize for another month.

Graph that shows the timing of several variables affecting the start and end of hibernation in bears.

These graphs chart the relationship between physiological parameters of brown bears in Sweden. Den entry (left column) and exit (right column) are indicated by time zero (the green vertical line) to determine the sequence of physiological events. SDANN is the standard deviation of heart rate variability over five minute intervals. It was used a proxy measure of metabolic activity. A red line denotes when a variable was decreasing, while a blue line indicates when a variable was increasing, with the number of days from the entry/exit indicated. From Drivers of Hibernation in the Brown Bear and reposted under the Creative Commons Attribution 4.0
International License.

Even though the bears’ physiology initiates the ultimate beginning and end of hibernation, climate plays a role in this process too. Changes to body temperature before den entry were affected by ambient air temperature, but bears largely relied upon a physiologic slowdown to cool themselves. In spring, bears left the den when the weather was right, exiting when air temperature rose to above 3.7˚C ± 1.5 ˚C (38.7˚F ± 2.7˚F).  Some biologists have suggested that food availability drives the timing of den entry, but this study did not attempt to test the hypothesis.

As a survival strategy, bear hibernation is remarkably efficient, and no other animal attains the same physiologic feats. Small mammal hibernators wake to pee; bears don’t even need to do that. Changing from an active metabolism to one of hibernation and back again takes a lot of time. If you are fortunate enough to see a bear in the middle of fall or the middle of spring, that bear is likely living in a transitional body equipped to handle two worlds—one with food and one without.

 

Filling the Gaps: 274

/ Mike Fitz / 8 Comments

In the fall of 2016, a bear with a distinctive light-colored patch of fur on its left shoulder was seen at Brooks River. The identity of this bear, at the time, was a mystery. It behaved like it knew its way around the falls and looked like a bear I should recognize.

The problem was I didn’t. So, I speculated. Based on the bear’s shoulder patch, I said it could be 469, a bear who is not often seen at Brooks River but became of interest to webcam viewers in 2013 as he dealt with a leg or foot injury.

Afterwards, the mystery bear was sometimes labeled as 469 in photos and videos.

I was never sure of this ID. The bear’s face, overall fur color, and body size didn’t match 469, but my suggestion fueled further speculation when the bear returned in 2017.

I now know my identification was incorrect. Katmai’s staff has since identified this bear as 274.

bear standing in water with gull in background

Bear 274 Overflow on September 27, 2017. NPS photo.

274 is a maturing adult male and is believed to be the offspring of 438 Flo. Unlike most brown bear cubs, he and a sibling remained with their mother through four summers (most mother bears in Katmai keep their cubs for two to three summers). This is the only example of a brown bear family in Katmai remaining together for four summers.

bear family with older cubs sitting on grassy island

438 (center right) sits with her two 3.5 year-old offspring in 2010. One of these cubs, perhaps the bear on the far left, is believed to be 274.

I never had the opportunity to watch 274 in person in the fall as he is an infrequent visitor, which is perhaps the reason I was mistaken originally. Bears have distinctive features that allow us to identify them across seasons and years. Yet, they can be notoriously difficult to recognize from early summer to fall. 274’s wide-set blond ears and shoulder patch should remain distinctive identifying features during future autumns. His current shoulder patch, it should be noted, wasn’t present in 2012, the last time he was positively identified in the fall.

bear walking in water next to grassy bank

Bear 274 in September 2012. NPS photo.

As he continues to grow, we could see 274 attaining a higher rank in the bear hierarchy. During the last few years he’s not been timid when using Brooks Falls, but he’s also not been large enough to occupy the most preferred fishing spots without being displaced regularly. If genes (which control his potential for growth, health, and lifespan) and fortune (which provide the opportunity for him to attain his physical potential) align, then 274 could become one of the more dominant bears at Brooks River.

brown bear sitting and looking towards camera

Bear 274 in July 2016.

Filling the Gaps

/ Mike Fitz / 3 Comments

Last July on bearcam, we witnessed the ascent of 32 Chunk in the hierarchy at Brooks Falls. Chunk was the largest bear to consistently use the falls in July, and most bears didn’t challenge him. We watched Chunk interact with many bears, occasionally with some that I (and many bearcam watchers) didn’t recognize. In mid July, for example, we saw Chunk displace another large adult male.

GIF of bear on left moving away from approaching bear who appears at right.

In this GIF from July 2017, a unidentified bear avoids the approach of 32 Chunk.

At the time, a few bearcam watchers speculated the subordinate bear may have been 856, who was the most dominant bear at Brooks River for many years. As I wrote in a previous post, I didn’t think this was 856. So who was it? Was he a previously identified bear or a newcomer to the river?

Before his seasonal position ended this fall, Ranger Dave from Katmai posted photos of several bears who were seen along the river, but were unknown or unrecognized by webcam viewers. Assuming Ranger Dave’s IDs are correct, which they are much more often than not, the unknown bear in the GIF above could be #611.

brown bear standing in water

Bear 611 at Brooks Falls in 2017. Photo courtesy of Dave Kopshever and Katmai National Park.

611 is a bear I don’t know much about. According to my notes, he was first identified in 2015, but only in September and October not in July. Preliminary bear monitoring data from that fall state this bear was an older subadult or young adult at the time.

611_09162015

611 in September 2015, the first year he was identified. NPS photo.

I may be splitting hairs or misunderstanding Dave’s intent, but note that Ranger Dave said, “This is believed to be 611” when he posted the photo. Perhaps there’s still some uncertainty regarding the ID. Filling in the gaps of who’s who at Brooks River can be difficult, and it isn’t possible to identify every bear with certainty. But—based on scars, size, head shape, and ear color—I am fairly convinced the bear in the 2017 photo posted by Ranger Dave is the same bear that Chunk displaced in the GIF above.

At Brooks River, I made the effort to learn to recognize the bears who used the river frequently. Since bear behavior is often complex and can vary from animal to animal, recognizing individual bears leads to a better understanding of their growth, behavior, and strategies for survival. If 611 returns in 2018, we’ll have another opportunity to observe his behavior. Will he challenge other adult males for fishing spots or will he avoid confrontation more often than not? Whatever happens, it will allow us to learn just a little more about the bear world.