Their long forked horns may have been used by rival males in competition.

Individual bulls "tend" cows until allowed to mate, by following them around and chasing away rival males.

In addition to the father, the stallion must also fight rival males to get the young mare.

Thus, a consort pair is likely to attract the attention of a rival male.

However, the male platypus also makes use of it when competing for territory along a river, although its effect on rival males is not known.

The display may also have the added benefit of deterring rival males.

Fights between rival males are sometimes fierce and long, and may even be fatal.

They are intended to frighten off the rival male.

Eventually, he'd be too weak to fight off rival males - and a challenger would dethrone him.