Oct 30, 2020

Morro Bay Wildlife Spotlight: Brown Bears and Black Bears



Black bear sighting in Los Osos

A black bear (Ursus americanus) recently swam across the southern end of the Morro Bay estuary and made its way onto land in a residential area of Los Osos, near Pasadena Point. The bear spent some time napping in a tree before officials with California Fish and Wildlife tranquilized and transported it to the Los Padres National Forest.

A black bear climbed a tree in Los Osos. Photograph copyright Ashbrd, https://www.instagram.com/ashbrd/?hl=en
This black bear swam across the south end of the Morro Bay estuary, came on land, and climbed a tree in Los Osos on October 22, 2020. Photograph copyright Ashbrd, shared via Instagram @ashbrd.

This incident reminded many of us that the lands surrounding Morro Bay are still wild and able to support large mammals, like black bears and mountain lions. Though black bears are omnivores and eat berries and grasses in addition to smaller mammals, they can function as apex predators, helping to keep populations of prey animals in check. This is a good thing for the ecosystem as a whole, since it leads to a greater variation of wildlife in the area.

Geographic movement and genetics of brown bears

The natural history of bears in North America goes back to the end of the Pleistocene Epoch. Fossil evidence shows that brown bears entered North America about 70,000 years ago. Phyleogeographic records—a branch of science that studies how genetic variations are distributed—shows that these bears most likely came from Asia.[i]

A large brown ber walks across grass. There are evergreen trees in the background and leafless tress in the foreground. It looks ahead.
This is a North American brown bear, photographed by JLS Photography in Alaska shared via Flickr Creative Commons License.

Disagreement over brown bear subspecies

Scientists have disagreed on whether the North American brown bear (Ursus arctos) should be considered one species or split into subspecies. In 1918, C. Hart Merriam proposed a whopping 80 subspecies of brown bears. His classifications were not widely accepted at the time, and science has continued to progress since then.

For decades, scientists generally considered there to be two subspecies of North American brown bear, including the Kodiak bear, which lives in Alaska, and the grizzly bear (Ursus arctos horribilis), which the town of Los Osos claims as its namesake (more on that later). Brown bears that live further inland were typically classified as grizzly bears, while bears that live along the coast and have access to marine food sources, such as salmon, were generally classified as North American brown bears.

Recent studies, however, indicate that there is not a genetic distinction between grizzlies and North American brown bears. The two names, brown bear and grizzly bear, are often used interchangeably.

History of bears in California

Brown bears

Brown bears, more commonly called grizzly bears have been a symbol of California for hundreds of years. In 1769, a group of missionaries led by Gaspar de Portola came through the area surrounding the Morro Bay estuary and, after seeing many grizzly bears and hunting some of them, called it Los Osos.[ii] The name remains today.

Grizzly bears were plentiful up through the 1840s, when Northern California residents reported—with perhaps some exaggeration—that, “you couldn’t ride on a horse for a mile without seeing ten grizzly bears.”[iii]  Unfortunately, settlers hunted these bears unrelentingly, so much so that they had almost disappeared from the wild by the 1860s.

Despite their decline, authorities chose the powerful grizzly bear as the focal point of the California State flag when it was designed in 1911,[iv] just eleven years before the last wild grizzly was killed in Ventura County in 1922.

Flag of California.svg
By Devin Cook, via Wikimedia Commons.


Black bears

Historical record of bears in San Luis Obispo County

Brown bears are native to San Luis Obispo County, but black bears are not. Historical records show that black bears lived in the southern Sierra Nevadas hundreds and even thousands of years ago, but they did not move into the San Luis Obispo area until the 1930s, after grizzly bears had been hunted out of the area. This may be due to competition for resources between the two species. Brown bears are typically much larger than black bears and, from time to time, may even prey on their smaller ursine cousins.

Black bear standing in grass.
This black bear was photographed in Sequoia National Park by Michael Gat. Shared here via Flickr Creative Commons License.

Local population of black bears

Today, scientists estimate that more than 1,050 of the state’s 30,000 estimated black bears live in San Luis Obispo County. That’s about 3.5% of the state’s total black bear population. (In contrast, the county is home to about 283,000 of California’s 39,960,000 human residents, or .07% of the total human population.)

Black bears: adaptable omnivores

Black bears are omnivores, adapted to eat both plant and animal matter. If a salmon run is within range, bears may catch spawning fish and eat their roe; this happens every fall at Lake Tahoe’s Taylor Creek. Some black bears have been seen catching and eating deer fawns.

This black bear, which, like some of the species is actually a cinnamon-brown color, wades into Taylor Creek to catch Kokanee salmon.
Don’t let the cinnamon-brown color of this bear fool you. It is a California black bear; they can vary in color from black, to dark brown, to this much lighter brown color. This bear is wading into Taylor Creek to catch Kokanee salmon. Photograph by Rose Davies from Flickr, shared under a Creative Commons License.
Kokanee salmon like these spawn in Taylor Creek in Lake Tahoe every fall. Photograph by Rose Davies via Flickr, shared under a Creative Commons license.
Kokanee salmon like these spawn in Taylor Creek in Lake Tahoe every fall. Photograph by Rose Davies via Flickr, shared under a Creative Commons license.

However, despite their powerful legs and long claws, they mostly forage rather than hunter. California black bears forage for a range of food; depending on the season, they may eat including ants, other insects, grasses, berries from manzanita trees and other plants, or acorns.

Morro manzanita with berries. Photograph courtesy of Jerry Kirkhart via Flickr, shared via Creative Commons license.

Ways to stay safe while hiking in black bear habitat

When you are hiking in areas where black bears might live, you can take some precautions to keep yourself—and any black bears you happen to meet—safe.

Here are a few tips:

  1. Try not to surprise a bear; they may become aggressive if you do. To avoid this, announce your presence by making noise while hiking, stay on the trail and out of thick brush, and keep your dogs leashed.
  2. Stay aware: watch for places where bark has been stripped off trees, keep an eye out for animal carcasses, and look for bear tracks and scat. If you see these signs, it might be time to turn back or take another trail. Click here for more information and images of bear tracks, scratch marks, and scat.
  3. If you do see a black bear, back away slowly, do not run, and do not make eye contact. Give the bear the chance it needs to avoid you. If the black bear has not seen you, make noise when you are a safe distance away so that the bear will move to a different location.

These tips are adapted from advice given by the California Department of Fish and Wildlife

This black bear track was photographed in Trinity National Forest by Josh Gross. Shared here via Flickr under Creative Commons License.
This black bear track was photographed in Trinity National Forest by Josh Gross. Shared here via Flickr under Creative Commons License.

Works cited

[i] https://fitznaturalist.com/2018/03/29/difference-brown-and-grizzly-bears/

[ii] https://www.sanluisobispo.com/news/local/news-columns-blogs/times-past/article234816692.html

[iii] https://www.scpr.org/programs/take-two/2012/10/24/28981/monarch-the-sad-amazing-story-of-the-bear-on-calif/

[iv] https://www.scpr.org/programs/take-two/2012/10/24/28981/monarch-the-sad-amazing-story-of-the-bear-on-calif/

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