Just as a hen is about to lay an egg, she applies a liquid coating around it that naturally protects against contamination.

FORBES: Natural Protection

If a cowbird female fails to lay in a warbler nest in time for her egg to hatch with those of the host, she can reset the clock in her favour by killing the first clutch.

ECONOMIST: How cowbirds run protection rackets

It took Rovio 51 tries, and a brush with bankruptcy to lay its golden egg.

FORBES: Angry Birds Developer Partners With Medio As It Heads Into Billion Dollar Valuation Territory

Since 2011 their home life has been watched via a "nest cam" and on Monday viewers saw Genevieve lay her first egg of 2013.

BBC: Monty the osprey