You are giving new information. In post four you said no shell was left so I assumed the whole egg was taken. Then in post seven you said there was wet stuff left, so no, it is not a snake. They would swallow the whole egg and leave no evidence. My mistake. I got tunnel vision when I thought the whole egg was gone because that fit my experience with a snake and a broody so well.
I don’t know if you have any predators in Australia that would eat the shell like that. That would be pretty unusual. They should be after the insides because that is where the nutrients are. Unless they eat the egg whole, they should not be interested in the shell.
The way I understand it, you have two broodies in two separate nests. 4 eggs disappeared under one and 2 under another. Did this happen at the same time or did the eggs disappear over a few days? I’ll guess it happened all at approximately the same time.
Sometimes a hen will eat the eggshell from a broken egg, sometimes not, but that is a lot of egg shell for one or two hens to clean up. Or maybe something was carrying off the eggs and broke one and left liquid and the hen cleaned up the shell. The scenario where the hens cleaned all the shell up makes the most sense.
Here in the States, rats, possums, or skunks would be the most likely suspects to eat the eggs out from under a broody and not carry the eggs off to eat them, but squirrels, chipmunks, and someone even said gophers would do that. I’d think something relatively small or they would have eaten all the eggs. From what you described, it sounds like something big would have trouble getting in there anyway. And for some reason it would have gone from one nest to the other, not finishing all the eggs in one nest. If something like this happened, I’d mostly suspect a rat but you have some strange animals Down Under.
I occasionally find an egg broken or usually punctured by a toenail. This could be under a broody or just a regular egg laid that day. This is practically always a very thin-shelled egg. It was so thin the toenail just punched right through. This would not be six eggs at one time. So with six at a time in to different nests this was not from another hen laying in there or the broody turning her eggs. Some event happened.
It’s possible the broody was defending her net from a predator and some eggs were broken in that process. With two different broodies in two different nests, that doesn’t sound likely, but it is possible.
Many broodies have no problem sharing their nests with other hens for them to lay their eggs, but some will defend their nests from those hens. Eggs could be broken in that type of fight. I don’t think that has ever happened to me but I’m not watching them all the time.
With you feeding the broodies in the nest, it’s possible another regular hen was attracted to that food and a scuffle broke out. They do like to scratch when they are eating and some food was probably in the bedding, so maybe no scuffle, just scratching for food. I don’t consider this a likely scenario but it’s possible like some of the others I’ve mentioned.
One thing that has happened to me before with two broodies at the same time. One had been broody for a while and was to hatch in a couple of days. The other had just gone broody and didn’t have any eggs yet. When the eggs started internal pipping the two broodies fought over the eggs. About half the eggs were destroyed in that fight. So one likely scenario is that your broody hens fought over the eggs.
You have some options with two broodies. I think the eggs are all due to hatch at the same time. I suggest you fix up a place where you can lock up one broody so she cannot get back to her nest. You need a nest, room for food and water, and room for her to go poop without messing up the nest, food, or water. Make the nest kind of dark. That seems to help them accept the move. And make it really predator proof, like rat proof.
At night, after it is dark, move one of the broodies in here with as little light and commotion as possible. Put all the good eggs under the other hen and put fake or sacrificial eggs under the hen you moved. The risk is that she may break from being broody when you move her but you have the luxury of the second broody if this happens. If she accepts the move you can either move the good eggs under her and break the other broody or get some new fertile eggs for one of them.
With something like this happening it’s hard to know what actually happened. There are a lot of possibilities and even the far-fetched ones are possible. I lean toward the two broodies fighting or something like a rat, but I’ve seen some strange things happen. Good luck!!!
