Number of Black Bears in the San Gabriel Mountains

The quoted number of black bears, like nearly all the estimated animal numbers except possibly the number of bighorn sheep, is quite uncertain since no regular census is conducted counting these animals. Since 1983, the California Department of Fish and Game has estimated a population of 400-500 bears. When asked by the press, the spokesman for the DFG, Patrick Moore, has given the lower number in "low production" years, and the higher number in "high production" years. Thus, for example, the number given in PSN on 5/27/99 was "about 500" black bears.

A "recent survey" of ANF personnel yielded estimates of 150-200 up to 400-500 bears "depending upon the biologist contacted".

Source: email from Patrick Moore, 8/23/99.

In addition, the number of black bears changes as a function of time.

Source for Dr. Stewart's estimates: Patrick Moore email, 9/6/99.

The population estimates from various editions of TOTA are:

At a class taught in 1988, Pat Sullivan, director of the Eaton Canyon Nature Center, who is also a fish and game warden, gave the number as 40-50, which may have come from the same source used by Robinson.

Despite Robinson's comments about "the number is decreasing", even in the face of an increase in his reported numbers with time, there seems little doubt that the numbers are in fact larger in 1998 than they have ever been, as reflected in the current estimates by ANF biologists.

A "recent study" found that 50 bears have a home range that includes Mt. Wilson, which is only a small portion of the SGM. (LAT 12/10/01, B10R, which didn't give the reference for the study)

For comparison, the same Yosemite bear stock introduced into the San Bernardino Mountains at the same time has expanded from 16 bears in 1933 to 300-350 bears in the late 1970s to "over 300" in 1989. (The Natural History of California)

Other supporting evidence for an increase in the black bear population is the increased frequency of bears seen in the urban areas near the SGM:

The incidents came from a search of the the L.A. Times archive covering back to 1990. The dates are the date of article, usually a day or two after the actual incident.

The number of black bears in the San Gabriels probably leveled off by ~1991, as shown from the number of bears killed by hunters in L.A. County. Hunters killed 51 bears in L.A. County in 1991-1995, and 46 bears in 1996-2000. These numbers are highly consistent with an average of 9.7 bears killed per year, reflecting an approximately constant population. Since bears produce an average of ~0.5 offspring per bear per year, a population needs to measure in the hundreds in order to be stable against that loss and other mortality sources. Other mortality sources include cars and being killed by authorities after being labeled a problem bear for interactions with people. Jim Davis, a wildlife biologist with the California DFG says:

I think it's fair to say we are probably losing more bears to road kill than to what hunters are taking.

The overall number of bears killed by hunters per year in Southern California has grown significantly in Ventura, Riverside and Santa Barbara counties:

Los Angeles3511167129561313
San Bernardino1623221921241918171714
Santa Barbara2448681923201814

Numbers are from the California Department of Fish and Game, reported in the LAT 12/10/01, p. B10R. Hunting beings in late summer, and ends when a quota of 1500 bears in the entire state is reached, typically in late fall.

Other estimates of the black bear population are:

One has to be cautious in scaling the numbers from other areas, for a variety of reasons, including different densities of food supplies leading to different requirements on the average size of habitat needed, different number and types of animals also sharing the same food sources, different degrees of human influence (providing food sources, removing "problem bears", etc.) and so on. However, in the absence of highly reliable data, such estimates provide a sanity check on quoted numbers.

Hence we have chosen to simply quote the entire range of recent estimates, 150-500, made for the SGM. A number in that range seems reasonable compared to the other estimates.

For intellectual curiosity, to get more accurate numbers, there are at least two methodologies:

See Grizzly Bear And Black Bear Ecology . Both methods require some effort and considerable expense, so more than intellectual curiosity needs to be at stake to devote the resources to a count.

For the sources quoted here, and estimates of other animal populations in the SGM, consult SGM: The Numbers.

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Copyright © 1999-2001 by Tom Chester and Jane Strong.
Comments and feedback: Tom Chester | Jane Strong
Updated 17 January 2001.