Spring is transitioning into summer and mating season in Yosemite has begun! Bears are solitary creatures and aren’t often seen in pairs or sloths (a group of bears is called a sloth). However, there are a few common exceptions: when food is overly abundant in one specific place, when sows have cubs or yearlings, and in the late spring and early summer during mating season (May–July).
Bears generally become reproductively mature between the ages of 3 and 5 years old. Bears are polygamous, so it is common for an individual bear (of either sex) to mate with multiple bears within one mating season. A female bear may give birth to cubs with different fathers in the same litter. Male bears will court females with a variety of behaviors, including barking, biting, hugging, mock fighting, and kissing. This behavior can take between a couple hours up to a couple days.
Even though bears mate and eggs are fertilized in the spring/summer, embryonic growth will not occur until fall. This is because bears use a clever reproductive strategy called delayed implantation. This allows for bears to only have the number of cubs that their bodies are able to support over the winter. if they have a lot of fat stored in the fall, they are likely to have more cubs than if they are thin. On average, a bear will have a litter of two cubs, but a very well fed bear could have three or more! Likewise, a thin bear may only have one cub, or none that year. Cubs are born between January and February weighing less than a pound.
Females mate and have cubs every other year. Their cubs stay with them through their second spring, when it is time for the sow to mate again. This is when the one-year-old bears (yearlings) will go off on their own. These yearlings are often mistaken for cubs who are missing their mother. They are generally between 50 and 80 pounds and are trying to find their place in the landscape. Female yearlings are less likely to disperse than males, often having overlapping home ranges with their mother even into adulthood.
It is very important to always keep a safe distance from all wildlife in Yosemite National Park (a minimum of 50 yards from any bear). Mating bears can exhibit unusual behaviors and males may become more aggressive. Females with cubs can be protective of their young, and yearlings out on their own for the first time have a particularly hard time staying out of trouble with humans. It is crucial that they keep their natural fear of humans, and never learn about human food, so that they can remain wild. This is an exciting time to see bears exhibiting wild behaviors, but please, for your safety and theirs, always protect your food from wildlife and never approach wild animals, even if it means giving up on that perfect photo opportunity.
Trails make getting through the rugged Yosemite wilderness easier for bears and humans alike. This GPS track shows an adult male bear that decided to follow a few of the scenic trails leading out of Yosemite Valley one day in the summer of 2014. Yosemite’s trails traverse much of the park, and humans and bears often agree on the best trailside rest stops, access to water, and cozy campsites. Unfortunately, this also means that bears can learn to associate busy trails with opportunities to find dropped food, unattended packs, and even beg for handouts. While it’s not necessarily common to stumble upon a bear while hiking, there are a few things people can do to help wildlife.
Wild bears naturally avoid human activity, but as a they spend time in the presence of people without experiencing negative consequences they may quickly become habituated. When bears become habituated to human presence, they lose their natural instinct to fear or avoid people and are more likely to spend time along popular trails. As bears learn to move comfortably in busy human environments, their opportunistic nature inevitably leads to conflict. A bear that spends significant time around people is much more likely to find an unattended backpack, open bear canister, or food trash. The first time a bear obtains high-calorie human food, it can quickly become food conditioned and preferentially seek out areas of human activity in search of it. This behavior often results in escalating conflicts where wildlife managers are forced to intervene; oftentimes on crowded trails or in remote wilderness locations.
With the privilege of hiking in the stunning Sierra Nevada mountains comes the importance of learning trail etiquette, including appropriate behavior around black bears. Day hikers and backpackers in Yosemite have the responsibility to stay within arm’s reach of their food while hiking by never leaving their backpack unattended or walking away from their food while picnicking. Anyone staying overnight in the park’s wilderness needs to carry an allowed bear-resistant food container to keep bears and other wildlife from accesing its contents (and so that a backpacker won’t lose all their food to a bear). It is important to give wildlife space (at least 50 yards for a bear), even if that means waiting for a bear to move off a trail before proceeding. Surrounding a bear on a trail may force the animal into close proximity to humans, block its escape routes, and/or create a dangerous situation for both people and the bear. If you encounter a bear on the trail, give the animal plenty of space and protect your food. Keep it with you. Do not abandon it, or throw it to the bear as a distraction. If the bear approaches you, a campsite, or is attempting to eat human food, gather together and yell, “Get out of here, bear!” as loudly as possible. Report all bear sightings to Yosemite’s Bear Hotline at 209-372-0322.
Although particular bears may seek out easy high-calorie human food, natural food sources are plentiful for the well-adapted American black bear. They do not need our food to survive, rather the opposite. They need to avoid our food in order to maintain their natural bear behaviors, and avoid conflict with people. Grasses, insects, berries, and acorns provide ample food for bears in wilderness. Remember, the ONLY help they need from us is respect and distance!
Leaving the yearlings at the den site was hard; after all the effort everyone had put in to get them to that point. Biologists watched their GPS data closely, and after about a month of hibernation in their human-made den, the bears began to explore their surroundings. Trail camera photos showed them playing with each other as they explored their new home, with the larger male expressing dominance and playfully chasing the others around their den site. After another month, the three intrepid young bears began to disperse, venturing to find their own home ranges and stake a claim in Yosemite’s expansive wilderness.
The smaller of two males settled in an area between Foresta and the El Portal Road, high on a ridge. He kept to himself, and moved around a lot, likely searching for various food sources, but he never interacted with people on trails or in developed areas. This bear’s collar stopped communicating GPS points to satellites in late spring. Without location data from the collar, biologists could now only track this bear using radio telemetry (which is limited by geography and distance: to pick up the collar’s signal via radio waves, biologists must be within ‘line of sight’ of the collar, and close enough to hear it using a radio receiver). It took the rest of the fall and summer before the collar was found, which required dedicated biologists bushwhacking several hours through manzanita on rough terrain. Unfortunately, when they found the collar, they also discovered remnants of fur and the bear’s ear tag which led them to believe the bear had died earlier in the year from natural causes. While the collar failed to transmit GPS locations after late April, data recovered from the collar indicates that this bear died in late June 2017. This bear was too far from development to assume that the death was related to humans, and it is common for wild animals to die naturally within their first few years of life (generally, about a quarter of black bear cubs are expected to die during their first year, and a third die within the next two years).
The small female sibling settled in an area near Yosemite Creek, deep in the wilderness. Her collar transmitted until the day it automatically dropped off in July. Our last glimpse of her was along a trail, far from roads and people; she looked healthy and acted skittish around humans. She may end up living 30 years or more in Yosemite’s wilderness, raising cubs of her own, foraging on wild berries and insect larvae, existing as an integral part of the glorious wildness she was born into.
The third cub, the larger male, had a more elaborate (and cautionary) story. For quite a while, this bear found good natural forage around a closed seasonal campground in the park. However, once the campground opened to visitors in June, the bear began foraging opportunistically in the same area on human food and garbage that was either left out or improperly stored. Very quickly, staff from across the park pulled together and began an around the clock effort to protect this tenacious little bear, including continuous education of campers, increased trash pick-ups, and long nights of chasing the bear out of the campground in hopes of convincing him that people were scary, and not worth the opportunistic food rewards. However, when all of these efforts were clearly not working to change the bear’s behavior, biologists decided to try relocating the bear. While bear relocations are generally unsuccessful, they sometimes work on young animals that are still establishing home ranges. So, this bear was relocated a short distance away in suitable habitat, where he immediately went back to foraging naturally and avoiding people.
A bear’s life, however; revolves around a continuous search for food; and since food availability changes seasonally at different elevations, bears must move to follow that available food. Heading into fall, wildlife management staff began receiving reports of this bear seen passing through a residential area over 15 miles (as the crow flies) and roughly 4,000 feet lower in elevation from where he spent his summer. By November, this bear had dropped down into the park’s administrative site, El Portal. There, the bear was gorging on natural food, including wild grapes and acorns. The only problem was that all this great natural food was, again, close to people; in a residential area and next to a busy highway. Bears that become comfortable close to people around homes worry wildlife managers, because it only takes one human mistake, like leaving a window open or garbage out, for a bear to get a large amount of food and associate this reward with people and houses. If that happens, it can immediately and dramatically alter the bear’s behavior as it shifts to actively seeking out human food or breaking into buildings instead of continuing to forage naturally. Knowing this, wildlife management staff again dedicated their time to scaring the bear out of developed areas and increased efforts to alert the community to be vigilant about food storage.
Days passed with community members and park staff pulling together in hopes of keeping this bear safe until the season turned and winter arrived, when food would become scare and this bear would hopefully find a den for the winter away from the neighborhood. Unfortunately this time, all of the hard work and joint efforts to give this bear a long, wild life eventually failed. On October 30, wildlife management staff found this bear, orphaned after its mother was hit and killed by a car, also dead in the road. It was a somber day. We all know that speeding kills bears—or more accurately, driving kills bears–—but it was hard to stomach that this would be the fate of a bear who we thought we saved from the same tragedy two years earlier.
This project, along with the data we have collected over years of careful monitoring of bear vs. vehicle collisions in Yosemite, has hit home with resource managers and many others in Yosemite. All it takes is having to drag one dead bear off of the road in order to realize how impactful our driving can be to other species. Wildlife-vehicle collisions are one of the largest human-wildlife conflicts we face today, and we all need to do more to change these statistics. This is an issue the National Park Service has worked hard on with limited successes in past years. With as many as 39 reported bears hit by vehicles in the park in a single year, we are dedicated to use this new momentum to refocus our energy on creating new partnerships, new tactics, and new solutions for this difficult problem.
In January 2017, the sibling yearlings—orphaned after their mother was hit and killed by a car on Independence Day, 2016—had been in hibernation for more than a month already. The cubs, once weighing eight pounds each, now weighed between 63 and 95 pounds, after being well nourished through their first year by the Lake Tahoe Wildlife Care Center (LTWC). They were healthy, fat, and ready to be transferred back to the park to a pre-selected den site that biologists prepared in Yosemite’s wilderness for this purpose.
In preparation for their return to Yosemite, park biologists went to LTWC to assess the yearlings’ body condition and health, and to fit them with GPS collars, which were funded by donations to Yosemite Conservancy. The collars would allow park staff to monitor how long the bears stayed in the den and to watch the movements of the cubs once they left the den in search of food. The collars were programmed to automatically drop off after six months, before the cubs outgrew them, and the information collected by these GPS collars would allow biologists to better understand the bears’ behaviors and how successful they were as wild, independent bears.
As the park biologists made the long drive back to Yosemite with bears in tow, a group of thirty park employees and volunteers made preparations to ski the bears on sleds to the den site. This included retrofitting rescue sleds with bear traps, harnesses for people to pull and push the bear traps, and preparing hot water bottles and lining the traps with hay to keep the sedated bears warm on their trip. With everything assembled, three teams began transporting the precious cargo up the mountain while one biologist skied alongside each sled to monitor the bear’s condition during the journey.
It took several hours and a lot of work, but all three bears arrived at the designated site. In the winter of 2016 to 2017, California broke its five-year drought with impressive amounts of snowfall. This allowed for great skiing and promising conditions for the yearlings to remain in the den. It also meant that the den site, which was located at the base of a tree, was now under six to 10 feet of snow. Staff excavated a hole to get down to the opening. Each bear was carefully lowered into the den with hopes they would remain there, sleeping the rest of the winter.
The yearlings had made it back to Yosemite, and back into the wild after seven months. The bears had been given the best chance possible, and now their fate was their own once again. They were returning to what we hoped would be a wild and free existence. Everyone present took a moment to appreciate the magnitude of effort it took to get these bears through their first year, and to say goodbye to these bears that we would hopefully never see again as they lived their lives, far from people as wild bears.
To be continued in next month’s blog.
It was Independence Day weekend 2016, and Yosemite was bustling with people hiking, camping, and taking in the scenery. For most visitors, Independence Day is a welcome break, a long weekend in the middle of summer. For park staff, it’s the busiest time of year, and employees across the park work hard at their jobs through the holiday providing visitor services and protecting the park. That morning, the wildlife management staff got one of those calls they dread the most: a bear was hit and killed by a car while crossing Tioga Road.
Between 1995 and 2017, an average of 18 bears have been reported hit by vehicles each year in Yosemite. Of those, 27 percent are found dead or are euthanized after park rangers determine the bear has an incapacitating injury. Bears that aren’t incapacitated by their injuries typically flee and their fates remain unknown. Some are OK, some sustain an injury that will give them a lifelong limp, and others ultimately die as a result of their injuries. Most bears are hit by cars from June through September, which coincides with Yosemite’s busiest months for visitors and the time during which bears are most active.
Ultimately, the human-bear management story in Yosemite is a metaphor for all the ways people and bears overlap in this beautiful place. Bear-vehicle collisions are possibly the most visual, most literal, and most heartbreaking example. While being called to a bear hit by a vehicle is unfortunately common, this particular incident was anything but routine. When rangers arrived on scene, they discovered that the dead bear was a lactating female and that there had been possible sightings of three cubs in the area. This news forced biologists to drop everything else to focus on these three orphaned cubs.
Cubs are generally not successful surviving in the wild in their first year without their mothers. Young bears spend their first 16 or so months with their mother learning how to forage, keep away from predators, hibernate in the fall and winter, and a whole host of other life skills. So even though young bears may not need the nourishment from their mother’s milk, they need her life experience and knowledge to survive. Consequently, leaving these cubs alone would almost certainly ensure their deaths.
With the hopes of getting these young bears through their first year, biologists and park staff mobilized quickly to find and capture the cubs while simultaneously seeking placement for the cubs at the Lake Tahoe Wildlife Care Center.
Biologists set out small metal cub traps and were fortunate to capture all three cubs within an hour of each other (similar captures in the past have taken more than 24 hours!). Shortly thereafter, biologists transported the cubs to the wildlife care facility. The cubs remained at the facility through the remainder of the summer, fall, and part of the winter. The goal of the rehabilitation was to fatten them up enough to give them the best chance at surviving on their own the following year with as little human interaction as possible so they would retain their natural fear of people when reintroduced to the park the following winter.
(Part two of this blog will be available on March 5)
It’s January, but Yosemite has only seen a small amount of snow. So where are the bears? Are they hibernating yet? The answer might be more complex than you’d expect. Hibernation in black bears is dependent on food availability – meaning that once a bear is using more energy than they can find, they’ll hibernate. Bears that continue to find enough calories foraging in the late fall and winter may go into hibernation later, or skip it altogether (these bears are more often males). Likewise, if bears have access to human food or trash in the winter, they may skip hibernation altogether, even in winters with heavy snow accumulation. There were several accounts on social media of this occurring last winter in the Tahoe Basin. It’s critical to maintain proper food storage year-round. Making the assumption that all bears are hibernating as soon as the weather cools off is a common mistake that can be much more difficult to correct than maintaining proper storage of human food and garbage year-round.
Most years, the majority of bears in Yosemite begin closing in on a hibernation location starting as early as October. GPS data paired with observations of family groups in the spring have shown that pregnant females are the first to select dens. Bears in Yosemite typically select hollowed out fire cavities in large trees or caves formed by large rocks in talus fields. The majority of the dens we have located here in the Park are very difficult to access with protected entry ways and good vantage points to observe potential threats from the entrance. Once the den location is selected, bears may continue to move around scouring the area for food while continuing to prepare their den. We can see this behavior using their GPS data as they begin to travel much smaller distances, circling back to their chosen den site. GPS data has also shown that bears often move into their dens, even traversing long distances, in advance of the first significant snow storm. Once the availability of fall foods fade, they will enter their den and begin hibernation (typically later in November, and December).
In the late fall and winter months, we remove the BearTracker data to ensure the locations of the bear’s dens are protected. Hibernation is incredibly important for bears and is physiologically astonishing. While hibernating, bears don’t eat, urinate, or defecate. Preparation for a very short gestation drives pregnant sows into dens that will protect them from the elements and predation. Cubs are born in late January and nursed for the first few months of their lives. It’s an important time in a cub’s life since they are born weighing less than a pound and must gain several pounds before venturing out of the den. Once in hibernation, bears in Yosemite typically don’t become active again until late March or April. When they do come out, they’ve lost up to ⅓ of their body weight, and spend their time foraging on early spring foods-usually fresh grasses in meadows. Males are typically the first to emerge for the season while sows with cubs are usually the last to emerge for the year.
So, where are the bears now? Most of them are hibernating, but not all! This is turning out to be one of those late hibernation years for some bears. We have observed several bears continuing to forage on this year’s plentiful Black and Live Oak acorns at lower elevations throughout December. Even females and their cubs were out late, as you can see in the image above of a sow and her cub’s tracks in the snow that was taken in late December.
When visitors see us moving a bear trap in Yosemite National Park, they often ask: “So…where are you taking that bear?” When we discover a black bear obtaining human food and damaging property in Yosemite, we capture it to identify it and usually attach a tracking device. So, why then don’t we simply relocate the bear to a remote area of the park? Indeed, the National Park Service did that for many years. In recent years we’ve all but stopped this practice here. Why? It doesn’t work.
Relocation implies that once moved the animal will stay put. There are several reasons moving bears doesn’t work. The most obvious — they usually return, often very quickly. For that reason we have adopted the term “translocation,” which implies that if you move a bear out of an area there is no guarantee it will stay put. More often than not translocation is nothing more than a temporary fix to a much larger problem.
For the first time in Yosemite wildlife biologists have a new tool to remotely track bears — GPS collars. To test the theory that translocation could be an effective management tool, several bears have been moved as far as possible within park the park boundary since 2014. This blog focuses on an individual we moved in 2015. As you can see from the map below, the bear returned to nearly the exact location in Yosemite Valley in less than a week. It’s unclear how bears navigate back home but they do it consistently, as generations of wildlife biologists and park rangers can attest. (The old joke is that the “relocated” bear beats the wildlife management truck back to Yosemite Valley.)
Sometimes bears don’t return home. In these cases it’s usually because they have found easy human food in another location (a nightmare for bear managers located hours away). In other cases bears may get hit by cars while trying to return home or may be chased off by other dominant bears already living in the area they were moved to. These bears could also chase off a less-dominant bear already living in that area. Simply put, moving bears into foreign locations, away from their home ranges and into those of other bears, can cause a negative domino effect.
So what should Yosemite do when a bear starts investigating human food sources? Our focus is to prevent that animal from ever obtaining human food in the first place! The techniques wildlife biologists use to manage black bears are often ineffective as long as bears are able to access human food. It is the crux of human-bear conflict. It’s up to us to store food properly so bears and other animals can’t obtain it. If we all do our part, these animals can retain their natural avoidance of people and have the chance to live a long and wild life. After all, if bears can’t live in national parks, where can they live?
National parks exist to protect wild and inspirational places, unimpaired, for this and future generations—to create the opportunity for people to experience these regenerative natural places, for the most part, as they would be without the impact of human development. But for wild animals, even our short visits to observe and recreate can have immense effects.
It’s early summer, and calls are flooding into the save-a-bear hotline. “A bird is stuck in our foyer,” “There’s a rattlesnake by my front porch,” and “How do I get a squirrel out of my Sprinter van,” interspersed with the occasional “There’s a bear in the meadow about 20 minutes from here.” With limited resources and staff, we prioritize our responses by how urgent calls seem to be, and when we first heard about this bear, it sounded fairly innocuous—there’s a bear in the meadow about 20 minutes from here in an area marked by meadows overflowing with the young grasses that bears depend on in the spring. It wasn’t until a couple of weeks later that we were told how close the bear had been getting to park visitors. Apparently, he had sauntered within five feet of people multiple times. If this bear was to remain wild, we had to act immediately.
Within a day, a team of wildlife biologists, technicians, and volunteers were heading out on a darting mission for the bear. By five o’clock that night, the bear, an adult male, was located, darted with a sedative, and fitted with a GPS collar: one of our most effective tools in the constant battle to keep Yosemite’s bears safe and wild.
Bears are incredibly intelligent animals, and this one is no exception. He had been spending time closer and closer to human development. Without any negative repercussions, he had been losing his natural fear of humans—becoming “habituated” to human presence. Once bears become habituated, the likelihood of them being involved in conflicts with people skyrockets— which puts us (and the bear) into bad situations. This is why collaring this bear quickly was so vitally important: Once he was collared, we could keep track of his movements (hourly!) and scare him away whenever he came near human development.
We got to this bear in time. Our intense efforts to reinstill his fear of humans were successful. If he had been fed by visitors, we may not have been so lucky. This bear hasn’t been near campsites or human development at all recently. But for him, it may have been out of the frying pan and into the fire. Today, watching his movements via the data from his GPS collar, we are seeing a surprising trend since he gave up on development: Possibly because of all of the seed-producing trees and grasses that grow in edge ecosystems, he has been spending all of his time on the roadsides of one of the busiest roadways in the park.
Somehow, this bear has crossed this major road hundreds of times since his capture in June. With 27 bears hit by vehicles in the park last year, this realization shocked us, and I think we are all holding our collective breaths for him. Even with a program as proactive as ours, even with the technology available to us with GPS tracking, we can’t protect this bear from careless drivers. Now it’s a waiting game, and we are all rooting for him. But it’s up to all of us—visitors and employees—to take it upon ourselves to remember that the bears of Yosemite spend their lives struggling to fit into our unique dichotomy of our ‘wilderness’ and the millions of people who are inspired by it each year.
Stay aware, drive slowly (Yosemite’s bears have more at stake than a speeding ticket), and if you’re lucky enough to see a bear in the park, take time to appreciate how many challenges it has probably overcome to be where it is. The resilience of wildlife is awe inspiring—even more so as they navigate through a world decidedly trammeled by humans.