A few weeks ago, I posted asking visitors, and enthusiasts if they had questions about Yellowstone grizzly bears. These were some of the questions folks had; I tried to answer questions to the best of my abilities based upon current science. Some questions may have been more policy related (away from ecology and biology), and opinion based. In these instances, I tactfully attempted to answer the questions with the best interest for the species in mind.
Q: How often do grizzlies leave their den in the winter (if at all) ? I’ve heard several different answers to that question A: There isn't really a straight forward answer for how often or how many times bears will leave their dens during winter/hibernation. However, there are reasons why they may leave their dens. There have been instances of black bears/grizzlies emerging, wandering a bit and then returning to their den (they do not stray to far). However, there may be a wide range of reasons for premature emergence. Sometimes this can be attributed to human disturbance (recreational activity, skiing, snowmobiling, etc.). Other times, it could be because of favorable conditions not requiring a bear to remain in hibernation. In Florida, male black bears have a much more condensed denning period, some not even hibernating or denning at all! Food availability affects when bears enter, and when bears emerge from hibernation as well. (Cited: Haroldson, M. A., Ternent, M. A., Gunther, K. A., & Schwartz, C. C. (2002). Grizzly bear denning chronology and movements in the Greater Yellowstone Ecosystem. Ursus, 29-37.) Q: How many grizzly bears are in Yellowstone? A: Just in Yellowstone alone, there is an estimate 150 grizzlies. This is a conservative estimate. In the Greater Yellowstone Ecosystem, as of 2016, approximately 690 grizzlies. Q: Tyler, the white bark pine nuts seem to be an inconsistent source of food for the bears, What determines a good year for the crop versus a bad year? A: They are inconsistent as a food source. The inconsistency in their availability can cause several things to happen. First off, let me address what determines a good year from a poor year. Ultimately, the number of pine cones produced; the number of healthy and pinecone producing trees. This is largely affected by the mountain pine beetle infestation. Pine beetles are native to the Rocky Mountains. However, because of continued climatic imbalances, warmer weather and less harsh winters at higher altitudes has allowed these beetles to infest even the highest standing groves of whitebark pine. This isn't good news for bears, but also isn't good news for clark's nutcracker, and pocket gophers. The pinecone itself contains pine nuts, which are high in fat. When in heavy abundance, these are a great food source for grizzlies. Moreover, there should not be an extreme worry about a shift away from whitebark pine. Grizzlies are omnivore generalists and have dietary plasticity (opportunistic). Typically, years where the whitebark pine have good seed crops, grizzlies (male and females) will be found at higher elevations (whitebark are high elevation trees). When whitebark pine crops fail, grizzlies tend to forage on root crops at lower elevations, also in search of ungulates (this brings them closer to people and roadways anecdotally). It has been observed that grizzly mortality is higher during years of poor whitebark pine production and availability. Changes in food abundance or sources is not an indicator to predict survivability or survival rates, unless the bears move to an area of larger human disturbance. Though, just because bears move to lower elevations doesn't mean they will suffer increased mortality; it is when bears shift to lower elevations and areas that have been altered by humans that creates more risk for them. Bears that shift to lower elevations in secure habitat (home range) are obviously not exposed to the same risk. (Cited: Schwartz, C. C., Haroldson, M. A., & White, G. C. (2010). Hazards affecting grizzly bear survival in the Greater Yellowstone Ecosystem. Journal of Wildlife Management, 74(4), 654-667. Cited: Logan, J. A., Macfarlane, W. W., & Willcox, L. (2010). Whitebark pine vulnerability to climate‐driven mountain pine beetle disturbance in the Greater Yellowstone Ecosystem. Ecological Applications, 20(4), 895-902.) Q: Just one question, are they protected from hunters? A: In the National Parks, yes. Currently, management has been turned over to the states since grizzlies have been delisted. There is no active hunting season for grizzlies in the states of Wyoming, Montana, and Idaho currently. That will most likely change in the future. Q: Okay, I have been reading that there are quite a few male bears, black and grizzlies still roaming, not in a den. Why do you think that is? A: Based on denning chronology, male grizzlies typically enter their dens later, and emerge earlier than other demographics in their population (females with cubs, solo females). Less than 10% (cumulative) of males in the grizzly population emerge from their den between the 4th week of January and the 1st week of February. Typically, bears will emerge from hibernation when food becomes available (mid March for males is typical). However, there can be a wide range of reasons for premature emergence. This can sometimes be attributed to human disturbance (recreational activity, skiing, snowmobiling, etc.). Other times, it could be because of favorable conditions not requiring a bear to remain in hibernation. In Florida, male black bears have a seriously shorter denning time as compared to northern black bears (this is if they den at all! (Cited: Haroldson, M. A., Ternent, M. A., Gunther, K. A., & Schwartz, C. C. (2002). Grizzly bear denning chronology and movements in the Greater Yellowstone Ecosystem. Ursus, 29-37.) Q: Since the closing of the dumps in the 70's and over time the grizzly became once again to fear human contact, and not associate people with food, do you feel that today's grizzly in the park have become re-conditioned to humans and food, and if so, what can be done to correct the problem without de-listing them and making them fear hunters again? I ask because I feel strongly that 150 in the park today is a terrifying low number, and unacceptable if they het delisted. A: So to answer your first question: Grizzlies do not become conditioned to people. I think you have the terms "conditioned" and "habituation" maybe confused. There are some individual bears that have a higher tolerance for dealing with people, tourists, and wildlife managers. This we would call being habituated to human presence. Is this a huge issue? I personally do not see this as an enormous issue. Food conditioned bears: I feel the park service and the forest service have done a fantastic job educating people about food storage and taking precautions to ensure bears do not obtain human food rewards. Your question pertaining to delisting; the purpose of the endangered species act is to recover populations and restore them to a standard they are able to be "delisted." If we were to keep species listed forever, the act would lose purpose. Keeping species protected longer unnecessarily causes the act to lose its teeth. It is easier to delist, then relist - rather than to keep animals listed unnecessarily. 150 bears is an extremely conservative estimate for Yellowstone alone, as is 690 for the entire ecosystem. There could be as many as 300 grizzlies in Yellowstone, and maybe even 1000 in the ecosystem. It depends which numbers you look at. It is a reasonable concern about hunting; some bears are so habituated they would become easy targets for hunters. In this scenario, some wildlife managers, biologists and others have suggested a buffer zone around the park; this would be an area that would be off limits to hunting. Q: Tyler I grew up in the Yellowstone area and have always wondered why we can’t get a solid count on the number of Grizzlies in the ecosystem. Is there anything new to assist in determining the population? And have the Grizzlies moved into the Snake River range? A: Large mammals, especially carnivores, given any environment (Yellowstone) are extremely hard to count. You will never account for 100% of the population. Statistical methods are often applied to help wildlife managers and researchers estimate population . With grizzly bears, monitoring unique females with cubs-of-the-year yearly help us gather useful information to gauge population (stats can also help account for bear families not observed). I would get into the specifics of this, but it can be confusing and hard to understand. Currently the Interagency Grizzly Bear Study Team (IGBST) uses Chao 2, mark recapture, to estimate the population. To my knowledge, no grizzly families were identified in the Snake River Range area during 2016 or 2017. However, that is not to dismiss the possibility that grizzlies could be in that area. Male bears have much larger home ranges than females, so the possibility could exist. Maybe a transient bear. You just never know! It is a lot of area for people to cover and examine. (https://www.usgs.gov/science/interagency-grizzly-bear-study-team?qt-science_center_objects=0#qt-science_center_objects) (Cited: Long, R. A., MacKay, P., Ray, J., & Zielinski, W. (Eds.). (2012). Noninvasive survey methods for carnivores. Island Press.) If you have any further questions, please feel free to comment below, or send a message using the "contact tab" on the upper bar of the website page. Thank you!
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For many, coming in contact with a black or grizzly bear in Yellowstone or Grand Teton National Park can be a very humbling and rewarding experience. Every year, thousands of visitors are given the chance to view these bears in their wild habitats. However, once you move across the park boundaries, you often come into contact with National Forest land, or public lands leased for agricultural purposes, even private ranches (livestock, etc.).
Coexistence in bear country is an issue that has been brought into the spotlight over the past several years. As grizzlies expand their occupied range, and move into areas absent of their presence for decades, home owners, ranchers and farmers alike face issues such as property damage and even livestock depredation. Whether you manage an orchard, or raise livestock, chances are you may fall victim to the presence of bears either now or in the near future. Understanding principles of coexistence and using proper preventative techniques can help mitigate the chance for possible damage. Home and Cabin Owners: Preventative techniques and measures home owners can take are fairly simple and easy to act on. For homes where fruit bearing trees are present, it is important to harvest ripe fruit and fruit that may fall to the ground; this will reduce the risk of attracting bears. Promptly removing garden refuse is also very important as it can serve as a bear attractant. While many home owners enjoy the presence of song birds at feeders, not using bird feeders or bird suet from March through November can reduce bear attraction to a residence. Highly aromatic garbage removed from inside a residence can be a very strong bear attractant, especially when containing meat scraps, or fish. To minimize the chance of a bear making a mess by getting into your garbage, use bear resistant garbage cans to dispose of your waste. If you are a cabin owner, you should take special precautions to reinforce windows and doors. Bears have immense strength and can easily break in a window or door when motivated. If cooking outside your cabin, you should clean grills, picnic tables, and ensure all food scraps are gone. This also helps reduce the presence of ants or bees, which can attract bears, leading them to create or cause property damage. Livestock and Agriculture: Preventative techniques and practices to minimize disturbance to livestock and agricultural operations, are important to reduce bear-livestock depredation and property damage. Animals that give birth, must be securely confined, housed, and protected to reduce risk of bear attraction. It is also critical to remove or secure all afterbirth and carcass materials. Poultry and livestock housing including pet kennels, should be erected 150 feet from areas of cover. Electric barriers around these confined units are strongly encouraged for deterring bears. Fencing is an important component while protecting livestock, and beekeeping operations. Implementing electric wires into fencing is very effective at deterring bears. Electric fences should be composed of 9 wires, and begin approximately 4 inches from the ground. To protect beehives and orchards, compost piles and gardens, individuals should construct electric fences at a minimum of 3 feet tall, wires spaced at most 10 inches apart. In some circumstances, it is important that fencing extends underground. At least 2 feet of fencing should be underground to create an apron, so that when a bear attempts to dig under the exposed area of fencing, that action is inhibited. Group beehives should be protected by using 6 foot tall livestock panels, or as an alternative, 6 inch square mesh fencing with an additional electric fence layer. Another method for protecting hives is using 15-20 foot tall platforms with support poles wrapped in sheet metal. While hunting, camping, or recreating in the backcountry of bear country, portable electric fencing units are also effective and encouraged. These same electric fence units also work for stock camps. In eligible counties within Washington, Idaho, Montana, and Wyoming, Defenders of Wildlife will compensate 50% of the cost for electric fencing to prevent grizzly bear access to livestock, attractants (garbage, orchards, beehives). ---Dohner, J. V. (2017). The Encyclopedia of Animal Predators: Protect Your Livestock, Poultry, and Pets; Identify the Tracks and Signs of More Than 30 Predators; Learn about Each Predator's Traits and Behaviors. Storey Publishing.--- While conducting research in the field, it should be the researchers last resort to place hands on wildlife. Reducing the amount of handling is critical. Similarly to humans, wildlife have numerous pressing stressors and threats in their everyday lives, and habitat they call home. Every second they are under anesthesia, and restrained, is time they will never get back. When they are captured and in our presence, we must bear in mind (no pun intended) that we are on their clock. A smooth, quick, and efficient handling process can assist in minimal disruption to the animal while returning it back to its habitat and home.
Collaring wildlife, especially bears and wolves has been disputed by many, including the public and researchers. While many see collars being invasive and cumbersome to wildlife, they are an important tool to wildlife management and research. Without the data gathered from these devices, we wouldn't understand a great deal of the information we have today (travel indices, locations, activity monitoring, home ranges, etc.) To the advantage of these wonderful pieces of equipment, a good majority of modern day GPS or radio collars have increased battery life, and technology to attempt and mitigate the need to re-collar an animal more frequently. Some collars are now designed as CRT, or known as commanded-released technology. This feature causes a collar to be dropped off an animal by a certain date, allowing for retrieval by researchers. However, some collars can give real time data; this is most GPS collars. A recently published study "Detecting Denning Polar Bears with Forward-Looking Infrared (FLIR) Imagery" uses both satellite and VHF transmitters fixed on the bears, in combination with FLIR technology. Polar bears emit approximately 200 watts of heat energy while denning; dens are 30 degrees celsius higher than ambient levels; surface areas over top dens averaged 10 degree celsius warmer, than those in snowbanks adjacent to the den. The researchers in this study hypothesized they would be able to detect these signatures using FLIR technology, and they were successful. This sort of technology could potentially, further minimize the handling of bears or other wildlife. FLIR technology in combination with aerial flights could allow for increase in better observability and add to current ecological survey methods. ---Amstrup, S. C., York, G., McDonald, T. L., Nielson, R., & Simac, K. (2004). Detecting denning polar bears with forward-looking infrared (FLIR) imagery. AIBS Bulletin, 54(4), 337-344.--- The unique science behind color: Interesting enough, color is one of the many things that people attempt to use to differentiate species of bears. Uniquely enough, black bears are not always black, grizzlies are not always brown.
Most of the time, black bears you encounter in the forests in the eastern United States are black in color. Occasionally, you will encounter small numbers of non-black colored black bears, but it is not very common. "Non-black black bears make up a higher percentage of populations going from east to west across Ontario, the Great Lakes region; these bears account for 5-10% of populations in western Ontario and Minnesota. Color ratios in the western regions of North America vary, from predominantly black, to predominantly non-black. The percentages of black individuals within populations decreases from north to south in the Rocky Mountain region and from the Pacific Coast inland. Black coloration occurs most frequently in very dense boreal, northern montane forests and temperate rain forests. Non-black coloration is found more commonly in open forest on the lower slopes of the northern and central Rocky Mountains, interior mountains in California, and desert ranges in the southwestern United States." --Rounds, R. C. (1987). Distribution and analysis of colourmorphs of the black bear (Ursus americanus). Journal of Biogeography, 521-538.-- These images of black bears were taken inside Yellowstone National Park. Color variation inside Yellowstone varies from black, brown, cinnamon and blonde. It is important to realize that color is not a very good indicator to identify species (grizzly vs. black). Color alone cannot identify a bear. In 2016, the northwestern corner of Yellowstone National Park was truly a hotspot for females with cubs-of-the-year (COY). During 2016, my study identified 3 sow's with COY inside Yellowstone National Park. The Interagency Grizzly Bear Study Team (IGBST) recorded 4 sow's with COY inside Yellowstone National Park.
While my study focuses on demographics and monitoring inside the park, the IGBST focuses on grizzly monitoring in the entire ecosystem. Outside northwest Yellowstone is where a large number of females with COY were located during 2016. Pictured is a grizzly sow seen on Swan Lake Flats during June 2016. This same bear pictured started with 2 COY, and days later was only observed with 1 remaining COY. Dr. Frank van Manen, the supervisory research wildlife biologist and head of the IGBST provided the following information regarding the documentation of mortalities for annual reporting purposes: "On the mortality list we document known and probable mortalities from all causes for dead bears; "known" refers to mortalities "in hand" and "probable" mortalities are instances with strong evidence that a bear died even though there is no carcass in hand. For independent age bears (>=2 years of age) we estimate total mortality from all causes and report that annually. This includes an estimate of unknown/unreported mortalities using a technique that employs an estimate of reported rate from radio-collared, independent-aged bears. We typically do not instrument dependent offspring (cubs and yearlings) unless they are involved in a management action. Thus we cannot obtain an estimate of unknown/unreported mortality for dependent young. This is why we only evaluate and report human-caused losses for dependent aged bears. For losses of dependent young from radio-marked females, we do document and include on the annual mortality list when they lose cubs-of-the-year. Cubs-of-the-year (COY) separated from their mothers have a very low probability of survival. We list them as probably mortalities because we rarely get a carcass in hand, but are reasonable sure they will not survive (however, we should not that some COY do survive and recruit in to the population: our genetic data supports the fact that some COY of killed females have survived). We also have data from both marked yearlings and DNA evidence shows that about half of the yearling that are separated from their mother survive and recruit into the population. Thus for the mortality list we do not assume yearlings died when they are no longer with the mother. Recall that we evaluate only human-caused losses for cubs and yearlings. However, when we derive our estimates of COY and yearling survival, we do include as dead both COY and Yearlings that are no longer with their radio-marked mothers, even though some survive. For this reason, IGBST estimates of COY and Yearling survival rates are likely conservative because they likely overestimate mortalites and thus provide a lower survival rate. If we were to make any changes we would likely stop including probable COY losses from radio-marked females on the list. After all, we are not able to observe losses of offspring from unmarked females so, if anything, we are somewhat inconsistent in reporting probable cub losses from radio-marked females." In my study, we speculate the missing COY is a "suspected" mortality (by definition not considered probable). However the mechanism and specific cause of disappearance or death remain unknown, and may never be revealed. That is the wild of Yellowstone. The Mystery of GB799: Hundreds, if not thousands of fortunate visitors were granted with the presence of a very large and blonde colored female with 3 cubs-of-the-year (COY) last May (2016) in Hayden Valley, Yellowstone National Park (image).
This bear, GB799, was seen frequently between Trout Creek and Mary Mountain Trail on the west side of Hayden Valley. She was notorious for roaming the sage flats; in 2016 her cubs were in tow, and some of the most playful and entertaining bears to watch. GB799 was first captured on October 15, 2014 at Trout Creek in Yellowstone National Park. She was fitted with a radio collar; that year she was observed with 2 yearlings. In 2015, GB799 was observed with no young. During 2016, GB799 was captured again, near Trout Creek in Hayden Valley. During this capture, 1 of her 3 COY was killed while she was in the culvert trap (2016 IGBST Annual Report). GB799 would have emerged this spring from the den with two yearlings. However, her collar was on mort, which is a signal given off after inactivity to signify mortality. GB799 was found dead early this spring; neither of her two remaining cubs were with her, and they never located during 2017. She was 14 years old this year. Her death remains a mystery; she died of natural causes but the specific mechanism surrounding her death remains unknown. If you are ever roaming the wilds of bear country, and fortunate enough to come across tracks, it's a very humbling experience. However, bear tracks and their patterns are typically very conservative in nature. Often times, signs in the general area can provide further insight and clarify what species was present. Though, it is often impossible to positively separate grizzly and black bear sign. There is no size criteria that will separate the sign of black bear from grizzly. The track of what someone may assume to be a female grizzly could actually be a male black bear. Generally speaking, black bear tracks are five inches (12 cm) wide or smaller. Black bears usually have short claws, often times not showing up in prints/tracks. It is very important to note that they presence/absence of claw marks does NOT positively identify the species responsible for the track. Grizzly bears leave tracks usually larger than 5 inches (12 cm) wide. On front foot tracks, claws when present form a pointed chevron (also can be present somewhat on the hind foot). One of the best clues for separating tracks of grizzly and black bears are found in the toes. In black bears, there is a greater arc in the toes; in grizzlies the toes are joined. Toes joined at the base, when visible, can possibly identify grizzly tracks. The front paw of a black bear, a line drawn from the base of the big toe (the outer most and outside toe) across the top of the intermediate pad will intersect the little toe at midline or above. When the same line is drawn on a grizzly track, it tends to intersect the little toe below the midline or not at all. ---Halfpenny, J. C. (1986). A field guide to mammal tracking in North America. Big Earth Publishing.--- These images were taken during September and October 2017 in Yellowstone National Park at an undisclosed location(s). Earlier this summer, many visitors were graced by the presence of several grizzlies near and on a carcass in Hayden Valley, at Grizzly Overlook.
A bull elk washed up along the bend in the river to the north of the overlook area, a little over 100 yds. off the roadway. This provided an exceptional experience for those visitors who were there to view it. Although speculation, the elk was likely struck by a vehicle, or taken down by the wolves, succumbed to its injuries, and drowned/floated down the river to where the bear was able to pull it near shore. Unfortunately, because it was a bull elk, the antlers are most desirable portion of the animal. An individual was observed walking out into the low lying river corridor area, where he then proceeded to cut the skull and antlers from the remaining neck tissue, and bring it up towards the road to his vehicle. Luckily, a good samaritan called the park and law enforcement was able to stop the individual(s) from taking the antlers and skull from the valley. A reminder that it is illegal to remove or possess natural or cultural resources (such as wildflowers, antlers, rocks, and arrowheads) while in Yellowstone National Park. GB399 is commonly referred to as "the matriarch" in Grand Teton National Park (GTNP). She is arguable one of the most iconic and famous grizzlies in the ecosystem, thanks to photographers, and visitors.
GB399 is 21 years old. She was captured and collared on August 25, 2016 with a new collar for research purposes. Last year her only surviving cub-of-the-year (COY) was struck and killed by a vehicle inside GTNP. With much skepticism, she surprised many by emerging from her den this spring with two new COY. Many were fortunate to observe GB399 the past several evenings foraging with her cubs on berries. Berries and other fruits are typically consumed by grizzlies in late summer going into fall. Because of their availability, berries and other fruits make up a very small portion of grizzly bear diets. Berries are a great source of carbohydrates to bears; that in combination with high protein foods (meats, etc) maximizes the grizzlies ability to promote fat growth and fat storage. In the coming years, it is possible that as whitebark pine fails and grizzlies begin to shift to other sources, that berries may become a critical component in their summer-fall diets. This has already happened in the Northern Continental Divide Ecosystem, where whitebark pine is almost non-existent and has disappeared; now berries make up nearly 85% of the summer-fall diet (Mattson et al. 1991a, McLellan 2011, Fortin et al. 2013, Erlenbach et al. 2014, Ripple et al. 2014, Ripple et al. 2015, Costello et al. 2016a) |
AuthorTyler Brasington is a native born and raised Pennsylvanian, yet proud current Wisconsin resident. He graduated from the University of Wisconsin-Whitewater with a B.S. in Environmental Science. Currently, Tyler is pursuing his masters in Natural Resources with the University of Wisconsin-Stevens Point. He has worked in Yellowstone National Park under the guidance and supervision of Dr. George Clokey and Dr. Jim Halfpenny. Disclaimer: The information and views expressed on this page do not necessarily represent the views of the Department of Interior, US Geological Survey, National Park Service or the United States Government.
The Greater Yellowstone Grizzly Project
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