Success - The Clutch

"As the egg travels down the tube it gets larger and larger. This is because during its passage (it takes about a day or two to travel all the way down the tube) various parts are added in turn to give the egg its essential parts – very much like it’s moving along a factory conveyor belt."

Source: swans life.com

"When the egg first emerges from the female swan, the colour could best be described as a bluish-grey. This colour is due to pigments are that added during the time when the shell was being formed, at the end of the oviduct. After the egg has been in the nest for a while, constant shuffling around in the cup of the nest by the pen, turns the egg more of an olive colour.

Eggs that have been in the nest for a while also exhibit many little scratches in their surface. These are due to them being stood on and being caught by the pen and cob’s claws on their webbed feet. The thick shell of the egg is easily strong enough to take the weight of an adult swan."