Animal Trivia # 4 Eggs

The eggs laid by a typical barnyard hen generally hatch in 21 days.

The eggs of most ducks and geese generally hatch in 28 days.

The eggs of a mallard duck will hatch normally in 35 days.

But surprisingly the eggs if both a parrot and an ostrich will hatch in 42 days; 

What is really amazing about these facts are ...
  
They are all divisible by seven, the number of days in a week!