Juvenile birds return to the colony three years after fledging, but do not mate for the first time until seven or eight years old.

For example, many birds mate for a breeding season or sometimes for life.

Once the birds have mated, the female returns to her home territory to lay eggs and raise the chicks.

The horn is shed after the birds have mated and laid their eggs.

They also feared that since adults mate for life, a bird whose partner was taken may not mate again.

These paired birds will mate every year between January and May.

Should one partner die long before the other, the surviving bird often will not mate again for some years, or even for its entire life.

The birds mate between the months of April and August.

These birds often mate for life, and both parents will participate in raising the cygnets, but only the female will incubate the eggs.

When the nest has been prepared, the birds mate so that the eggs are fertilised and the chicks will start growing.