How To Age Bighorn Sheep
in the Ruby Mountains
Other Bighorn Pages - Information | Photos | Observations | More Photos

This page will show you how to estimate the age of a bighorn sheep ram. Aging bighorn sheep rams is not as hard once you understand how the horns of a sheep grow. The horns grow during the summer with all of the good feed and warmer temperatures. Then fall and winter come. The ram begins to rut and stops eating as much. Also during the winter the quality of the sheep's feed is decreased compared to summer. This causes a ring to form on the rams horn. The first major ring forms when the ram is in his second winter and he is 1 1/2 years old, and then every year after.

More information that comes in handy when aging bighorn sheep is listed below.

  • Bighorn sheep are born around the end of May thru the beginning of June. Using this information you can age a sheep to within a few weeks.
  • When a sheep is born most of it's energy goes into body growth for the upcoming winter. At 6 months old a young sheep has almost no horns.
  • Once a ram comes out of it's first winter the rams horn starts to grow as the weather warms in the spring and the feed gets better. At 1 year old the ram is starting to grow some horns.
  • A rams first summer means a lot of growth for his horns.
  • Studies have shown that aging a bighorn ewe is very unreliable and at best will give a minimum age. The photos at the bottom of this page illustrate this.

    aging bighorn rams 6 months old aging bighorn rams 1 year old aging bighorn rams 1 year old aging bighorn rams 2 1/2 years old aging bighorn rams 4 years old
    Photo Taken In November
    This sheep is 6 months old.     		Photo Taken In May
    This ram is 1 year old.     		Photo Taken In March 2007
    This ram is almost 2 years old.     		Photo Taken In November 2007
    This ram is 2 1/2 years old.     		Photo Taken In March 2009
    This ram is almost 4 years old.

    Rings on a 2 1/2 Year Old Ram

    The Sheep pictured to the left is 2 1/2 years old. Using the photos above you can judge his age so far.

  • The very tip of his horns looks different and is darker colored. This was his horn growth from birth to 6 months. Sheep will loose this section of their horn as they grow older. Notice the tips of his horns match the other 6 month old sheep above.

  • The second small ring up from the tip marks his age at 1 year. This ring is not very pronounced and is easy to miss. This ring will tend to disappear as the sheep grows older and start to broom his horns. Notice that this ring matches the horn length of the 1 year old ram pictured above.

  • The third ring from the tip marks his age at 1 1/2 years. This ring was formed during his second winter and is the first ring that is very pronounced. This ring will be easy to see the rest of his life unless he really brooms his horns a lot or breaks a horn.

  • A ram will form a ring in his horns every winter. Since we see the ring when he was 1 1/2 years old and we know that he will form another ring this year we can add another year to his age. This would make this ram 2 1/2 years old. It is too early in the winter for this ram to form this ring. In the spring when his horn growth starts again the ring formed from winter will become visible.

    • Rings on a 7 1/2 Year Old Ram

    The Sheep pictures to the left is 7 1/2 years old. Using the photos above you can judge his age.

  • As you can see the tips of his horn is splintered and does not come to a piont. This ram has broomed or broken the growth from the first 6 months of his life. But this is not all that he has removed. There is also no ring from when he was 1 year old. This has also been removed. The first major ring that is visible is from when he was 1 1/2 years old. This is now the first ring from the tip of the horn.

  • Since a ram forms a ring every winter we can add a year for every ring that was formed. This ram has 6 visible rings on his horns.

  • We know that this ram will form another ring this winter. So we can add another year to his age. This would make this ram 7 1/2 years old. It is too early in the winter for this ram to form this last ring. In the spring when his horn growth starts again the ring formed from winter will become visible.

    • The photos below show the same ewe 2 1/2 years apart. Notice that there is minumal horn growth during this 2 1/2 year period.
    how to age bighorn ewes
    Photo taken April 2007.     		how to age bighorn ewes
    Photo taken October 2009.

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