Rats :(

Half inch metal hardware cloth seems to keep them out.

My first thought is, set aside some time, pull bedding out, look for how they are getting in and repair that. You may need to build a door or something with the hardware cloth to block their entrance.

Then replace the bedding.

Set up some water traps (a bucket half filled with water, with a dowel threaded through two level holes in the top, with peanut butter on the dowel) near the coop. The idea is the rat is attracted to the peanut butter, the dowel flips it into the water and it drowns. Or if that sounds unkind, if you know someone who is a good shot and can kill them, but then you must account for any ammunition so the ducks won't eat it and get hardware disease (metal toxicity, which is often fatal to the duck).

There is a Predators and Pests forum, too, you may be able to get more help there.

There are also smoke bombs you can place in their holes - but domestic animals are not to be near the area for four hours, and they are not to be used near structures.

 

There are non poisonous products that repel the animals. Or ultrasonic rodent repellents. Do some googling and see what you come up with. You can try a hav-a-heart trap (many times local animal shelters or animal control officers will lend them to you), along with the repellent products.
If you can only feed the ducks when they are locked inside a secure coop or shed, then there will be nothing for the rats to eat. Can you keep ducks inside till you can pick up the daily eggs? Once their food source disappears, then they will have to move along.

 

I keep my chickens and ducks in the same coop and the chickens keep out the rats and snakes looking for my eggs.

 

Ducks and chickens eat their eggs sometimes too. Usually they will break an egg by accident and after they taste the egg. They keep breaking them and eating the egg, but they don't eat the shell. It might be mice/rats but might be the ducks.

 

One of the fundamental approaches to prevent rats coming into your coop is to ensure that your ducks are not spilling food onto the ground. Spilled grain or food attract rats. By taking small handy methods you can save duck eggs. If you are facing major problem because of rats you can contact Rat Exterminator Sacramento. They take proper precautions while working so not to worry about your ducks.

 

I have snap traps that are protected by a box and up high so no ducks can get near them. Put peanut butter in the middle and the rats for for it every time.

 

They are essentially a bait station without poison but fit a trex snapper trap.