pectation that monitoring and studying of these 

 individuals would reveal information on den- 

 ning and pre-hibernation behavior. Two were 

 successfully tracked to their dens. The instru- 

 mented bears included a known-age sow, two 

 weaned yearlings, a two-year-old and a large 

 boar. The transmitters used on the grizzlies 

 were standard continuously pulsed tracking 

 transmitters, new extended-life transmitters em- 

 ploying an ON-OFF pulse pattern and tem- 

 perature-sensitive transmitters with the pulse 

 rate controlled by a thermistor. 



A Study of the Elk Population of the 

 East Fork of the Bitlerroot River 



This project was initialed in the fall of 1964 

 to evaluate the current status of the elk popu- 

 lation in the East Fork of the Bitterroot River. 

 In response to a noticeable decline in hunter 

 harvest of elk since the 1960 season, a con- 

 flict with the public regarding the elk popula- 

 tion arose. The intent of this study was to 

 present data facilitating more accurate conclu- 

 sions regarding the actual status of the elk 

 population. 



Herd numbers in the East Fork range from 

 an estimated seven head in 1902 to 651 in 

 1958, a gradual increase at an average rate 

 of 1.1 percent per year, with some short term 

 reductions. Recent management policies (1953 

 to date) have been based on the maintenance 

 of a stable population compatible with other 

 resource uses. The desired level of herd num- 

 bers is 500 to 600 animals. Aerial trend counts 

 from 1955 to date, excluding the year of 1963 

 for which an incomplete census exists, varied 

 between 522 and 651, averaging 590. Ground 

 observations, made during March and April 



from 1956 through 1965 indicated a sex ratio 

 of 20 bulls per 100 cows and an age ratio of 

 51 calves per 100 cows for the Bitterroot Unit. 

 For the years when data were recorded by 

 separate areas, the age ratio in the East Fork 

 has averaged 56 calves per 100 cows. 



The legal harvest in the East Fork in the 

 last 10 seasons has been 40 percent of the 

 total harvest of the upper Bitterroot. In spite 

 of low harvests in the East Fork in 1962, 1963, 

 and 1964. The average annual harvest has ac- 

 counted for 35.3 percent of the average annual 

 population estimate. Prior to the 1962 season, 

 the value was 40.4 percent. The average of 12 

 years' harvest composition data (1953 through 

 1964) is 195 bulls and 39 calves per 100 cows. 

 Age composition determined in the 1964 har- 

 vest shows that animals 2 '/a years and younger 

 constitute 75.3 percent of the total harvest, as 

 recorded through the checking station. No old 

 animals were observed in the harvest. 



The complex of temperature and precipita- 

 tion during the winter months directly affects 

 the extent of winter range for elk. In average 

 years, elk spend about five months on the 

 winter range. A mid-winter trapping and tag- 

 ging program at two sites in the East Fork 

 indicates that some elk which summer along 

 the Continental Divide (the Bitterroot-Big Hole 

 Divide) do not return each winter to the East 

 Fork. Tag returns from elk originally tagged 

 in the East Fork and later shot in the Big Hole 

 River drainage suggest intermingling of elk 

 between the two major drainages. A tag re- 

 turn from the East Fork of Rock Creek, an air- 

 line distance of about 30 miles from the initial 

 tagging site, points to movement over the 

 Sapphire Range. 



Research Projects 



Aging of Fishers and Analysis of Reproductive Systems Completed 



An Ecological Study of the Grizzly Bear Completed 

 An Intensive Study of Elk Behavior on the Mirror Plateau Summer Range, 



Yellowstone National Park -- - -- -- New 



A Preliminary Study of the Breeding Biology of the Spruce Grouse (Canachites 



canadensis franklinii) in Northwestern Montana . . New 



Bighorn Sheep Population Study Wildhorse Island Continuing 



Competition Between Big Game and Cattle in the Gird Creek Area of Montana . . New 



Developmental Behavior of the Pronghorn Antelope Fawn ... .. . ... New 



Ecology of the Golden Eagle Continuing 



Economics of Wildlife Production on Private Lands Continuing 



Elk Migration Study, Yellowstone National Park Continuing 



Magpie Population Dynamics Continuing 



Movements and Behavior of the Northern Yellowstone Herd on the Winter Range New 



Mule Deer Population and Range Studies in Western Montana Continuing 



Population Study of Canada Geese in the Flathead Valley Continuing 



Quantitative Aspects of Raptor Predation Continuing 



Radiotracking and Telemetering System for Large Western Mammals New 



River Classification and Evaluation Continuing 



Study of Alpine Ecology in the Northern Rocky Mountains Completed 



Systematics of Blue Grouse in Northwestern Montana Continuing 



The Elk Herd of the East Fork of the Flathead River Completed 



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