A Moment of Science

Sheep With Personality

So how do scientists measure the success of an animal's success? Find out on this Moment of Science.

A herd of Sheep.

Photo: northdevonfarmer

Older rams between ages six and twelve are typically the most successful.

“To boldly go where no man has gone before,” are famous words from the science fiction series Star Trek.  Being bold does tend to help people be successful in life, but what about bighorn sheep?

Well, it seems Canadian scientists have found that if you’re a bighorn ram, a bold personality can be a good thing. Scientists can’t measure an animal’s success by finding how much money it earns. Instead, they measure how successfully it reproduces.

Breeding Competition

Bighorn sheep rams compete in order to breed with females. Large size and high dominance status usually determine a male’s success.

Older rams between six and twelve years are typically the most successful, but paternity tests have shown that some younger rams also father offspring. So what’s going on?

Being Bold

Scientists believed successful younger males might have bolder personalities, but measuring personality traits is more complicated than counting offspring.

To measure boldness, researchers trapped animals in plywood enclosures and measured how much of a fight they put up when they were weighed and measured.

Wrestling Rams

Needless to say, sheep wrestling was not the safest way to gather data, but they found sheep had quite different personalities. At one end of the spectrum, some sheep were well behaved and sat while being measured.

At the other end were rams like Psycho who was very aggressive every time he was trapped. After all that wrestling, scientists did find that young rams who fathered offspring were the most combative, boldest males.

Unfortunately, bold rams tended to die earlier than their more docile peers because they took more risks. So, going boldly is not always the best choice.

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