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
are less likely to be eaten by predators, so
females, especially with lambs, might need to use
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. Im 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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