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).
Tyler 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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