Que Ser A Ser A

I am finding that the egg-laying of my ducks is slowing down this month.  I have gotten as few a 1 per day and as many as 5 per day this month.  My 10 Indian Runner ducks are now 1 year old this month. This is the first time they have slowed down since they started producing eggs at the end of December 2008, when they were 6 months old.