CDFW News

The Secret Winter Lives of Lake Tahoe’s Black Bears

Tue, 24 Mar 2026 13:41:59 GMT

Keep Tahoe Bears Wild!

Spring is in the air at Lake Tahoe, and black bears are emerging from their winter dens. This includes mother bears with new cubs of the year that are only about 8 to 10 weeks old.

The reproduction cycle began back in the spring of last year, yet the mother bear has only been pregnant since around Thanksgiving. If the math doesn’t add up, here’s why: Black bears have a unique reproductive cycle that allows them to mate in the spring/summer but delay true pregnancy until the fall to increase the odds of success for a healthy pregnancy and fetus.

Black bears mate in the summer from June to August, and the adult females undergo a process called delayed implantation. The sperm from the male fertilizes the microscopic egg inside the female, which quickly develops into a small ball of cells called a blastocyst. At this point, the pregnancy process pauses with the blastocyst floating around in the uterus, suspending further development until the fall. This pause allows time for the female to gain the fat reserves she will need to sustain both herself and any cubs she may have during the upcoming winter hibernation, or torpor, as it’s more accurately called for bears.

Hibernation is tightly related to resource availability, and bears prepare for it in the fall by entering a period called "hyperphagia" (pronounced hi·per·fay·jee·uh). This period is marked by a substantial increase in feeding activity when bears are known to consume about 25,000 calories per day. All bears experience this feeding frenzy whether pregnant or not.

As natural food supplies dwindle and snow gradually blankets the Tahoe Basin, bears naturally go into hibernation to save precious energy and resources. This is because bears do not eat or drink during hibernation, nor do they urinate or defecate. Instead, they have developed the ability to live off acquired fat stores and recycle wastes back into usable proteins. During this period, their heart and metabolic rates drop significantly, and they can lose 25 to 40 percent of their body weight.

The stresses of hibernation are even more pronounced for females with cubs. To prepare for hibernation, the female’s body will carry out a self-evaluation in the late fall. If she has acquired the necessary fat reserves to sustain herself and her cubs throughout the entire hibernation period, the blastocyst will implant onto the uterine wall, and the fetus will begin to develop. In other words, true pregnancy begins. If the female has not accumulated enough body fat, the pregnancy ends and the blastocyst is reabsorbed by her body.

Sometime before Feb. 1, a pregnant female will give birth in the den to a litter of one to four blind, naked cubs weighing less than 1 pound. The female hardly awakens from torpor during birth, becoming just alert enough to lick the cubs clean and move them into a position that keeps them warm and allows them to nurse. The cubs continue to nurse and grow, becoming more active through the remainder of hibernation. A female with new cubs of the year emerges from the den between March and May with cubs weighing around 5 to 7 pounds.

Throughout the cubs’ first year, they learn everything about how to be a bear from their mother, including where to find food and what is dangerous and to be avoided. Cubs of the year are dependent on their mothers for several months and are taught how to forage on natural foods, including grass, berries and grubs. A female with cubs will be busy caring for and teaching her new cubs and will not mate again in the summer. Cubs of the year stay with their mother through the following hibernation and their first birthday, emerging from their mother’s den again the following spring as yearlings. Newly emerged yearlings are typically 50 to 150 pounds, and though they may be a bit awkward, they are well equipped and ready to go off on their own. Mother bears, once free of these “teenagers,” will once again find a mate and breed to continue the cycle of producing cubs every other year.

As omnivores, a bear’s diet is about 85 percent plant-based, with the remaining portion coming from insects, small mammals and carrion. Bears provide essential ecosystem functions, including helping to spread seeds through their scat, transporting pollen on their fur and tongues, cleaning up animals that died during the winter and aiding in nutrient cycling by digging for insects.

Though seeing a female bear with her new cubs can be a very exciting experience, bears play an important role in Lake Tahoe’s ecosystem and allowing them access to human food and garbage is detrimental to natural processes and their health. When mother bears teach their cubs to access human foods, they not only continue the cycle of human food-conditioning, but the cubs are much more prone to conflict, including being hit and killed by vehicles. Cubs taught to seek human food sources do not learn how to forage naturally. Instead, once they separate from their mother, they become dependent on human food sources and pass on the same unhealthy foraging habits to their own cubs.

You can support black bears during their reproductive process by giving females with cubs plenty of space and by securing attractants and human food sources that may lead new cubs down a path toward conflict. It is a shared responsibility to keep Tahoe’s bears healthy, safe and wild!

For more information about black bear reproduction and cubs, visit January / February Is Birthday Time for Bears. For more information on coexisting with bears, visit BearWise.org or TahoeBears.org.

To report human-bear conflicts:

In California, contact the CDFW at (916) 358-2917 or report online using the Wildlife Incident Reporting (WIR) system at apps.wildlife.ca.gov/wir.
Non-emergency wildlife interactions in California State Parks can be reported to their public dispatch at (916) 358-1300.
In Nevada, contact the NDOW at (775) 688-BEAR (2327).
If the issue is an immediate threat, call the local sheriff’s department or 911.

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Media Contact:
Peter Tira, CDFW Communications, (916) 215-3858

Spring Weather is Coming and With it Some Very Hungry Bears: Keep Tahoe Bears Wild!

Tue, 01 Apr 2025 16:28:15 GMT

** A Tahoe Interagency Bear Team (TIBT) News Release**

The snow is already melting in the Lake Tahoe region, and the end of winter gives way to a busy spring for wildlife in the area. Bears that have been in winter dens are emerging, and they are hungry!

In the fall, bears went through hyperphagia (pronounced hi·per·fay·jee·uh), which is an increase in feeding activity (consuming about 25,000 calories a day) driven by their need to bulk up before winter. Over the course of the season, bear bodies utilize those fat stores during hibernation when food is scarce. Come spring, their body mass will have naturally decreased and, as a result, bears will be on the lookout for easy food sources to help rebuild those fat reserves. Bears will instinctively move to elevations where they can find fresh grasses and other plants. This search can bring them into neighborhoods.

As bears make their way through the area, please be vigilant about cleaning up and securing bear attractants. The Tahoe Interagency Bear Team (TIBT) emphasizes that properly disposing of and securing garbage is one of the most important things you can do to help keep Tahoe bears wild. Always remove food and trash from vehicles, keep windows closed and ensure doors are locked. Bears can open unlocked car doors and even enter through sunroofs to reach the smallest attractants like a stick of gum. Also lock doors and windows on buildings to prevent bear break-ins. The national BearWise program offers Six At-Home BearWise Basics you can take to live responsibly in bear country.

Individual Actions Can Impact an Entire Ecosystem

Bears play an important role in Lake Tahoe’s ecosystem. Allowing bears access to human food and garbage is detrimental to natural processes in the region. Bears help spread berry seeds through their scat, transport pollen, clean up animals that died during the winter, eat insects, and provide other essential functions of nature.

When bears find human food and garbage, bird seed, pet food, coolers, or other sources of unnatural food, the Tahoe Basin loses the benefits bears offer through natural processes. Unnatural food sources can impact their overall health by damaging and rotting their teeth and their ability to stay wild. In fact, bears will unknowingly eat indigestible items from human trash like foil, paper products, plastics and metal that can damage their internal systems and even lead to death. If these items do make it through their digestive system, they leave it behind in their scat rather than the native seeds and healthy fertilizer needed to grow the next generation of plant life.

Call the Experts

Spring is also the time of year that residents or visitors may see a bear they believe looks unhealthy, sick or orphaned. Bear health concerns should be reported to TIBT’s wildlife professionals at the California Department of Fish and Wildlife (CDFW) or the Nevada Department of Wildlife (NDOW). These agencies have the training, expertise, and veterinary resources to assess a bear’s condition and transport it for care, if necessary. Healthy bears mean a healthy Lake Tahoe ecosystem, but it takes everyone’s cooperation to contribute to the success of both. For great tips about living responsibly with bears, visit tahoebears.org and bearwise.org.

The bottom line is that Lake Tahoe is bear country. It’s up to everyone, including those living in, visiting, or recreating in the Tahoe Basin to practice good stewardship habits by always securing food, trash, and other scented items. Good habits will help ensure Tahoe bears remain healthy and wild.

To report human-bear conflicts:

In California, contact the CDFW at 916-358-2917 or report online using the Wildlife Incident Reporting (WIR) system at apps.wildlife.ca.gov/wir.
Non-emergency wildlife interactions in California State Parks can be reported to their public dispatch at 916-358-1300.
In Nevada, contact the NDOW at 775-688-BEAR (2327).
If the issue is an immediate threat, call the local sheriff’s department or 911.

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Media Contact:
Peter Tira, CDFW Communications, (916) 215-3858

Trail camera photo courtesy of John Axtell, Nevada Department of Wildlife.

Just the Facts About Lake Tahoe’s Black Bears: Keep Tahoe Bears Wild!

Tue, 18 Feb 2025 16:50:06 GMT

The Tahoe Interagency Bear Team (TIBT) is a collective of bear experts across federal, state and local agencies who study and understand bears and have devoted much of their professional lives to ensure the health and well-being of the Lake Tahoe Basin’s black bears. TIBT provides proven and scientifically backed information about the real issues and solutions for living and recreating in bear country.

Tahoe bears may at times seem unique due to their learned lack of fear and boldness around humans (habituation), but these black bears follow the usual biological patterns of black bears across California and Nevada. Whether living in or visiting bear country at Lake Tahoe or beyond, this information should clarify what is really needed to help wild bears survive and thrive.

Don’t Let Your House Become a Makeshift Den

Many have seen photos and videos perpetuating the myth that property owners and residents should allow bears to den under homes and in crawl spaces. Some may have even seen people encourage this unwanted behavior by laying out hay and other materials for bears. Surprisingly, however, most homeowners aren’t even aware that a bear is under or around their home until it has already established a makeshift den.

Bears often damage the insulation, exposing pipes to freezing temperatures or even damaging them in the process. Once a bear gets comfortable, it can be difficult to make it leave. This increases the chances of human-bear conflict and habituated behavior.

Bears under homes need to be addressed by trained agency professionals as bears can be dangerous. If disturbed, mother bears with newborn cubs may abandon the den, orphaning the cubs in the process. For this reason, only a wildlife professional should evaluate the situation and offer advice to homeowners.

It’s important to remember that bears have evolved to comfortably survive winter without human help, so it is essential to board up all crawl spaces around homes to discourage them from denning and damaging property. For more information about securing crawl spaces, watch this TIBT video.

Secure Your Trash

Black bears are very resilient and adaptive animals, and, as opportunistic omnivores, they will take advantage of any available food source, including human supplied foods like garbage. Their highly developed sense of smell allows them to find these food sources, even when locked in a vehicle or a home, which in turn may lead bears into conflict with people.

Never Feed Bears – Intentionally or Accidentally

It is true that bears need a lot of calories, especially in preparation for winter, but giving them handouts will not set them up to thrive. Repeated exposure to human foods can lead to food-conditioned bears that view neighborhoods as reliable sources of food.

When mother bears teach their cubs to access human foods, they not only continue the cycle of human food-conditioning, but the cubs are much more prone to conflict, including being hit and killed by vehicles.

Consuming human garbage can also be harmful for bears because the high sugar content can increase tooth decay and painful abscesses. Additionally, intentionally feeding bears is illegal in both California and Nevada.

As omnivores, a bear’s diet is about 85 percent plant-based, with the remaining proportion coming from consuming insects, small mammals and carrion. Thus, bears should be allowed to fulfill their very important and vital ecological role as seed dispersers, predators and scavengers.

Black bears are smart. They have learned how to unscrew lids and open sliding-glass and vehicle doors. They are also strong. In order to access food, they can peel a car door down from the top or break through a typical home door or window. Even after an incident like the 2021 Caldor Fire, where a huge swath of vegetation was burned, wildlife biologists saw these resilient omnivores find natural ways to survive.

Protecting Human Life and Property

On rare occasions, the California Department of Fish and Wildlife (CDFW) and Nevada Department of Wildlife (NDOW) must remove bears that are putting human life and property at risk. No one, including the agencies’ biologists who have dedicated their lives and careers to protecting bears, want this outcome. It is only used with great discretion and as a last resort.

Bears are large, strong animals and once they become conditioned to human foods or habituated to people, they pose a significant threat to human safety. For these reasons it is very important for people to be educated and dedicated to being “BearWise.” Learn how to live responsibly with black bears at the BearWise website.

It’s also important to note that except in the case of immediate protection of human life, the only people who can legally interact with wildlife are designated state agency or law enforcement professionals.

Protecting Bear Health and Wildness

It can be exciting to see a big, beautiful animal like a black bear in a neighborhood, but it is not where they belong. Human-developed areas pose many dangers to bears, particularly roads with cars, which bears must cross to get to the unhealthy human food and garbage in developed areas.

By allowing bears to comfortably live in or pass through neighborhoods, the chances that they will get struck and killed by vehicles increases immensely. If a bear is in your neighborhood, encourage it to move on by scaring it away so that it can lead a much safer life away from developed areas and conflict. For more information on bear-vehicle collisions, check out this TIBT video.

The TIBT is dedicated to creating the best environment for bears to thrive and remain wild in an ever-growing, ever-changing environment like the Lake Tahoe Basin.

CDFW and NDOW should be the only points of contact for any bear-related incidents or questions. CDFW and NDOW have trained black bear experts who can help navigate any human-bear conflicts.

Be sure to visit TahoeBears.org for accurate information about bears and to report any bear sightings or incidents.

To report bear incidents or conflict in the Lake Tahoe Basin, use the following:

In California, contact CDFW at 916-358-2917 or report online using the Wildlife incident Reporting (WIR) System.
Non-emergency bear collisions in California State Parks can be reported to public dispatch at 916-358-1300.
In Nevada, contact NDOW at 775-688-BEAR (2327).
If the issue is an emergency, call the local sheriff’s department or 911.

Thank you for helping keep Tahoe bears wild and safe!

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Media Contact:
Peter Tira, CDFW Communications, (916) 215-3858

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About the Tahoe Interagency Bear Team (TIBT)

The Tahoe Interagency Bear Team (TIBT) is a collaborative group of agencies and organizations trained and dedicated to reducing human-bear conflicts in the Tahoe Basin. The TIBT works together to promote bear safety through education, outreach, and the implementation of effective bear management practices. TIBT's efforts ensure that both bears and people can coexist peacefully in this beautiful region.

Fall Means Feeding Frenzy for Black Bears

Fri, 01 Nov 2024 10:33:08 GMT

Time to Secure Food, Garbage and Recycling: Keep Tahoe Bears Wild!

Autumn is here, and black bears are entering a temporary physiological state known as “hyperphagia.” During hyperphagia, also known as the fall feeding frenzy, bears consume as much as they can to bring their fat stores to a level where they can survive the quickly approaching winter months.

In the fall, an adult bear can consume 20,000 to 24,000 calories a day and can gain multiple pounds per day. To achieve this rapid growth in fat stores, wild bears begin foraging most of the day and night and may travel beyond their normal home range in search of food. The increased drive for food can lead bears to seek easy, calorie-dense meals in residential areas if food, garbage and recycling are not properly stored.

To keep Tahoe bears wild while they bulk up for the winter, the Tahoe Interagency Bear Team (TIBT) wants to remind residents to stick to BearWise principles by using bear-resistant garbage carts and bear boxes, removing bird feeders, storing pet food inside and cleaning outdoor grills regularly. Bears will follow their noses and this year’s rollout of the semiautomated, three-cart collection system in South Lake Tahoe and new disposal requirements make it even more imperative that residents do whatever they can to prevent bears from accessing human sources of food.

The national BearWise program offers the following tips to reduce the chances a hungry bear finds your trash:

Garbage and Recycling Pickup: If you have garbage pickup once or twice a week, put your trash cans and recycling containers on the curb the morning of pickup, never the night before.

Rinse: Take time to rinse out and clean cans, bottles and containers, including carry-out containers and pizza boxes so the odors don’t attract bears.

Compact: The less space your trash and recycling take up, the more space the garbage trucks will have.

Grind Up: Now is the time to put your garbage disposal to work. More down the drain means less out at the curb.

Freeze: Keep a bag in your freezer for anything that might smell before it gets picked up. Add it to your trash the morning of pickup.

Store Securely: If your garbage container is not bear-resistant, keep it inside a sturdy building until the morning of pickup. If it is bear-resistant, keep it closed and latched.

Learn more about bear behavior this time of year at TIBT’s Black Bears in Autumn YouTube video.

For information on acquiring approved bear boxes and managing trash and recycling in the Tahoe Basin, visit the South Tahoe Refuse & Recycling Services website.

Use the following phone numbers and online resources to report a bear incident or conflict while camping or visiting the Tahoe Basin:

In California, contact the California Department of Fish and Wildlife (CDFW) at (916) 358-2917 or report online using the Wildlife Incident Reporting (WIR) system at apps.wildlife.ca.gov/
Non-emergency bear collisions in California State Parks can be reported to its public dispatch at (916) 358-1300
In Nevada, contact NDOW at (775) 688-BEAR (2327)
If the issue is an emergency, call the local sheriff’s department or 911.

Learn more about keeping Tahoe bears wild at BearWise.org.

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Media Contact:
Peter Tira, CDFW Communications, (916) 215-3858

Bear Experts Offer Tips for Camping in the Lake Tahoe Basin. Keep Tahoe Bears Wild!

Thu, 11 Jul 2024 16:12:16 GMT

Headed to the Lake Tahoe Basin for a summer camping trip? Black bear biologists who work in the Tahoe Basin every day have some advice and thoughts to share to help keep Tahoe bears wild.

The Lake Tahoe Basin is the heart of bear country and bears in the basin are especially active and persistent in their search for food. Sometimes, the easiest food for them to find is human food and garbage.

“Anyone coming to the Tahoe area should educate themselves on bear behavior and general bear ecology. There are a lot of bears here and those bears have an incredibly strong sense of smell and a strong desire for food that intensifies at different times of the year, particularly in the fall with the onset of hyperphagia,” said Alexia Ronning, an environmental scientist with the California Department of Fish and Wildlife (CDFW) and one of CDFW’s human-wildlife conflict specialists assigned full-time to the Tahoe Basin.

Hyperphagia is the biological instinct for bears to fatten up for the winter, which drives them to consistently feed and search for food.

“Read and follow all the camp rules about bears when you arrive and take them seriously,” Ronning said. “If you do have an incident – whether it’s a bear getting into your car or getting into food at your campground – report it to your camp host or the proper government agency.”

Ronning encourages Tahoe Basin campers and visitors to pack a few specialty items to keep them safe while enjoying the outdoors and to help keep the Tahoe Basin’s bears from getting too close and comfortable around people, which is often the source of escalating human-bear conflicts. Conflicts are most likely to occur in settings where human food and garbage are present, such as campgrounds and neighborhoods.

“Consider carrying bear spray and read the product instructions carefully before going camping. Remember to spray bear spray downwind,” Ronning explained. “Bring an air horn and a whistle or bang pots and pans. Those noises will help scare a bear away to a safer distance and the noise will also warn fellow campers and hikers that a bear is nearby.”

Bear-proof ice chests are another essential component to any Tahoe Basin stay.

People assume their ice chests are bear-proof, but in most cases they are not. If they can’t be locked or latched securely with no way to pry a gap between the lid and the cooler, the ice chests need to go into a bear box. Campers need to have all the equipment to store food properly whether that’s a bear-proof canister for the backcountry or a bear-resistant ice chest for the campsite.

Once a bear gets a food reward it is more likely to come back so taking those preventative measures is the best way to keep campers and bears safe.

Toothpaste, deodorant, body spray, lip balm and similar scented items also attract bears and shouldn’t be left in vehicles, tents or loose around a campsite. These items should also go into a bear box or bear-resistant canister.

In the Tahoe Basin, bear encounters aren’t limited to campgrounds or backcountry destinations. Encounters can occur in neighborhoods, business districts and at any time, day or night.

One common problem Tahoe Basin bear experts see is conscientious campers using bear boxes for food storage and bear-proof dumpsters for garbage but not closing them securely. Those must be latched properly to be functional and effective.

Visitors to the Lake Tahoe Basin can play a key role in helping keep bears wild by practicing these strategies and being extra vigilant as bears approach the hyperphagia period.

For more tips and information about bear-safe camping, please see the following video from California State Parks and visit CDFW’s Human-Wildlife Conflicts webpage.

Use the following phone numbers and online resources to report a bear incident or conflict while camping or visiting the Tahoe Basin:

• In California, contact CDFW at 916-358-2917 or report online using the Wildlife Incident Reporting (WIR) system at apps.wildlife.ca.gov/.

• Non-emergency bear collisions in California State Parks can be reported to its public dispatch at 916-358-1300

• In Nevada, contact NDOW at 775-688-BEAR (2327)

• If the issue is an emergency, call the local sheriff’s department or 911.

Learn more about keeping Tahoe bears wild at TahoeBears.org and BearWise.org.

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Media Contact:
Peter Tira, CDFW Communications, (916) 215-3858