Bighorn Sheep Population Estimates
in the Ruby Mountains

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Rocky Mountain Bighorn Sheep Polulation Estimares in the Ruby Mountains, Nevada
Year Lambs Yearlings Ewe Class I Class II Class III Class IV Total Dates Counted Time Frame
2006 unk 2 13 unk unk unk 1 unk 3 counts | Rams winter range not counted in 2006. November 2006
2007 7 7 11 7 8 3 2 unk 5 counts | Rams winter range not counted in 2007. November 2007
2008 10 12 21 5 8 7 3 66 Total of 20 counts June 2008 thru May 2009
2009 0 5 10 0 1 1 0 17 Total of 10 counts as of June 2010. October 2009 thru June 2010
2010 0 0 9 0 1 0 0 10 Total of 10 counts for the year 2011. October 2010 thru February 2011

    This page is an accumulation of data gathered starting in 2006. It is an estimate of the Rocky Mountain Bighorn Sheep population that rut in Lamoille Canyon. It is my hope that this data can give insight into growth rates of different sexes and classes of sheep and help to understand how the herd ages.

    Most of the study area is located in Lamoille Canyon 40° 40' North 115° 27' West, in the Ruby Mountains, North Eastern Nevada. Areas studied where the bighorn sheep rut area along with the ewe winter range and the ewe lambing range which are located in Lamoille Canyon. Other areas studied where the ram winter range.

    How the counts were made:
    In the rut of 2008 a system was devised that I feel gathered good sheep counts of Lamoille Canyon.

    This system was made up of two parts.

    • Part One: This part starts the beginning of November and runs until the middle of December. I check Lamoille Canyon from the road and hiked a certain area of Lamoille Canyon during the rut.
    • Part Two: This part starts beginning of January and runs thru March. I would count the sheep in Lamoille Canyon in the same manner as during the rut plus rams where counted separately after they had moved into their winter range. The numbers gathered during the rut were then compared with numbers obtained after the rams migrated to their winter range. Comparing these two sets of numbers gives what I believe to be a very accurate count of ewes and rams that rut in Lamoille Canyon.
    The counts made where taken from June of one year to June of the next. Since the rut lasts into December and the rams do not move into the winter range until December to January it is important to count the rams in the winter range to get an accurate count on sheep that rut in Lamoille Canyon. Lambing is in May to June so the count ends in June.

    The bighorn sheep were classified into seven different categories as follows.

    • Lambs - Sheep estimated at 1 month old or less.
    • Yearlings - Young sheep 1 month to 15 months old.
    • Ewe - 15 months and older.
    • Class I ram - A young ram with the tip of the horn not past 09:00.
    • Class II ram - A ram with the tip of the horn not past 06:00.
    • Class III ram - A ram with the tip of the horn past 06:00.
    • Class IV ram - A ram with the tip of the horn past bridge of nose.

    Ram increase:
    In 2008 there where 12 yearlyings. These 12 yearlings would average 6 rams and 6 ewes. 3 rams in 2008 were harvested which leaves 3 rams. Figure a mortallity of one ram a year due to old age or slips, trips or falls and the total ram increase for 2008 equalls 2 rams.

    Yearling Increase :
    The counts from 2006 showed only 2 yearlings compared to 7 and 12 for 2007 and 2008 respectfully. At first it was believed that the 2006 count was incomplete. Although the area checked was basically the same for all three years (Ewe winter range). Research has discovered that the lamb count can vary greatly from year to year (Geist 1971). Other research shows that most adult ewes produce lambs year to year in some herds (Festa-Bianchet 1992).It is known that around five ewes did not move to the lambing range in 2008. These ewes stayed in the winter range with yearlings. We will be watching future years to see if the yearling count stays steady.

    Percentage of Rams to Ewes:
    In 2008 the Rams account for 55.3% of the herd that ruts in Lamoille Canyon (21 ewes and 26 rams). This coinsided with other studied herds of around 50:50 (Geist 1971)(MacCallum 1991) (Feder 2007).

    The pictures and information on this site are from Larry Spradlin or Bill Homan unless otherwise stated. If you want to use anything from this site please let me know by the email link on the home page and give this site credit. The images and photos on this site are copyright protected.