No one is completely certain why some animals
such as bighorn sheep segregate themselves
into male and female groups. Researchers are
testing a few hypotheses. A key observation in
this work is the difference between the size of
males and females, with males almost always being
larger. This is a type of sexual dimorphism
where males and females have different size, shape
or appearance (humans are very sexually
dimorphic). Differences in body size can lead
to other important differences between males and
females that may cause them to form separate
groups, such as:
Large animals are less likely to be eaten by
predators, so females, especially with lambs,
might need to use safer areas.
Large sheep might be able to eat more
fibrous (tough, low quality) food, because
their guts are larger. Therefore females may have
to use areas where higher quality food is
available. Also because females are bearing and
nursing young, they may need extra
Males and females may have very
different behaviors that cause them to form single
sex groups. For example, male sheep have to
learn to fight for females during the mating
season. They learn this from other males, which
may encourage them to form single sex
There are some other variations of these ideas
that are being explored by researchers. I am sure
that if you thought about it, you might be able to
think of a few others.
Another thing to think about is how you might test
these ideas. What observations would you make?
What information would you gather?
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