Because it is one of the first streams in the region where bright, energetic, and pre-spawned salmon are available to bears, the Brooks River hosts one of the greatest seasonal concentrations of brown bears anywhere on earth.The time of year along with salmon densities and spawning activity dictate when, where, and how bears feed along the river.
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How Many Bears Frequent Brooks River
During late June through July the annual cumulative total number of independent bears identified regularly using Brooks River during 2004-2008 has ranged from 43 to 70. During September through early October, the annual cumulative total has ranged from 45 to 59. Typically, another 5 to 10 transient bears have also been documented in each of the two monitoring periods annually.
There are several factors that may be related to the increasing trend in bear numbers at Brooks, including:
Over the past 20 years, increasing management emphasis has been placed on minimizing bear-human conflicts. Over their lives, the experience of cubs that accompanied their mothers to Brooks may consist largely of relatively benign contacts with people there. Thus, we would expect the number and proportion of adults tolerant of people to increase.
Salmon runs have been generally strong throughout the region during the past 20 years. In the Naknek River watershed, which includes Brooks River, the Alaska Department of Fish and Game has reported a 20 year average escapement of 1.8 million fish (1989-2008). During this same period, weather conditions have been relatively mild. Bear survival and productivity may have increased as a result.
Brooks River is one of the first streams in Katmai where migrating salmon become accessible to bears (and the caloric value of bright pre-spawned salmon is exceptionally high). In contrast, spawning and spawned-out salmon are available at several streams during fall. Differences in adult male representation between July and fall may in part reflect this seasonal distribution of resources.
Do the same bears return to Brooks River each year?
Yes. Typically many of the bears that are observed each year are recognized from previous study years.
During 2008, 59 of the 70 independent bears identified regularly using Brooks River during July were bears recognized from previous years, as were 35 of the 52 independent bears identified regularly using the river during fall. The majority of bears not recognized during both July and the fall were subadults. Recognizing bears from year to year is difficult; therefore, these figures should be considered minimum estimates.
A number of bears are also typically recognized each year between the July and fall (late August into October) periods of bear use at Brooks. However, it should be noted that recognizing bears between these periods within a single year tends to be more difficult than recognizing animals across years within the July or the fall bear use periods. Our minimum estimate of independent bears that were seen at Brooks River during both July and the fall of 2008 is 36. Analysis of DNA samples collected from bears at Brooks River during June-July and fall of 2005-2007 may provide additional insight regarding patterns of use by individual bears.
Numerous other bear watching opportunities exist within Katmai and information on areas such as HAllo Bay, Geographic Harbor, and the Crosswonds Lake, Funnel Creek/Moraine Creek area will be added later.