I've inherited a chicken-flock, and 2 Pekin ducks (Tweedledee and Tweedledum) came along with the package deal. when they arrived in January, they were laying 1 egg each a day for a few weeks. The shells were pretty thin, but they seemed to do the job. Then they both molted. They both started laying again around Easter. The shells were good and hard. they're actually really hard to crack. Tough little buggars. that went well for a few weeks. Ever since that, Tweedledee has started laying in On the days in between, she lays shell-less eggs. Not just 1 a day but up to 3 a day. It doesnt' seem to be a calcium deficiency, because her good eggs are really strong. It almost seems as though she's producing the eggs so fast that they don't have enough time in the "shell-chamber" to actually deposit a shell. Why would she be laying 2-3 eggs a day? The ducks are fed Purina Layena Plus layer pellets, since they are fed alongside the chickens. They forage for all kinds of nasty natural duck-food on 5 acres all day. We have lots of slugs for them.