Our Muscovy mommas have been sitting on their eggs for approximately 30 days... which should mean that they are about 3-5 days from hatching. This morning we went in the pen to let the ducks out of the duck house, and there was a broken egg on the floor of the house near the door. There was no rotten egg smell.
From their age I guess they weren't pipping the shell which means something broke in. If the eggshell is still around, if possible, check the break marks to try to see what did it.
In one case, a dog which had previously been very well behaved and trustworthy could no longer resist the rich smell of the eggs, it seems, and began stealing eggs at almost-hatching point. She would never do it when people were watching; she'd check on everyone's positions first, to make sure nobody was watching; then she'd remove the egg into the paddocks to eat it. No evidence was left but the shell, which I stumbled upon by chance, with the tell tale canine toothmarks spaced precisely at the width her teeth were; the next day we caught her in the act of strolling off with the next almost-pipping egg. Too late to save that one but the rest of the clutch was saved. No matter how much of a perfectly reliable and trustworthy angel your dog is, if you have one, assume it may be a culprit... Though in this case it sounds like an accidental break to me.
The egg shell was bloody on the inside, and up on a roosting bench (above one of the nesting boxes) was a small, bloody pile of something unidentifiable. (My son investigated further and found it was a partially formed duckling, maybe only half the gestation size of a fully grown egg.)
Because the duckling was not eaten, it's most likely in my opinion that it was an accidental break and one of the ducks did the instinctive thing and removed the broken egg so it wouldn't attract predators or harmful bacteria to the clutch.
Does anyone have an idea as to what happened? Did an egg break and one of the non-nesting ducks eat it? I'm not sure how the unformed duckling got up to the roosting bench. I'm not sure if one of the non-nesting ducks would steal an egg, break it, and eat it.
Yes, it's a possibility, but it's fairly likely you wouldn't have seen the duckling if this happened. They will, if instinctive enough, carry all broken eggs away from the nest site to save their clutches, and this goes for any avian species, basically, domestic or not.
If they did that, should I worry about it happening again?
Yes, very much so --- IF it was a deliberate break which I think unlikely, but I may be wrong. One tasty meal is enough to train even a rather unintelligent animal into repeating the actions required to get more of the same.
Why, after sitting for 30+ days on their nests, was the duckling so tiny? By my calculations they should be ready to hatch any day now.
Sounds like it was going to be a dud, possibly dead but not yet rotting... But due to your next sentence, there are a few possibilities.
(They rotate nests and share eggs.)
This is a serious issue. It rarely works out. When they share eggs, the eggs are being moved overly regularly and rolled more often than they should be, which results in breaks and embryonic deaths.
It's also an issue if they're close to one another as due to vocal imprinting, they can bond to babies not even in the same nest as them, which leads to violence and chaos when the mothers try to leave the nest and the babies don't know who they belong to, so they cry out in confusion and mild panic, which leads the mothers to try to claim and separate their clutches, thereby bringing mothers into conflict due to perceived hierarchy trespass and challenge.
Babies can and do imprint onto multiple mothers. I use this to my advantage to partially imprint poultry onto me, which makes for easier handling and more trust when they are adults. (I've never had violence issues with them despite the belief some have that this increases the likelihood of it... But, each to their own.)
Communal brooding also results in uneven incubation, so no egg is guaranteed to have received the correct amount of heating, so this less developed chick could simply have been one of the unlucky eggs who didn't get regular warmth.
No matter how they're acting right now, it will most likely change after or during hatching. One of the worst things is when they all respond to a hatchling trying to pip the shell by hustling around in the nest, shifting every egg as they try to all sit on the one that's hatching. Obviously this tends to result in death for the hatchlings and other eggs too.
It may still have been alive when the egg was broken, they can last much longer than their normal brood time if given enough heat to live but not enough to develop within the usual time frame.
Longest I've seen that work with a chicken egg is a month, which resulted in skinny (but live) hatchlings, which survived to adulthood despite the bad start.
When you allow group brooding, when they hatch, it results in all manner of chaos (except in the rare cases where it all works out) --- for example, all your broodies may abandon the nest for a single duckling, leaving hatching eggs to die, or they may allow the first hatchlings to starve and die because they're more strongly bonded to the nest, or because none of them bonded to it because of the presence of the other ducks.
You can end up with previously cooperative females battling over hatchlings, because their hierarchy, less active during brooding, will manifest itself when they cease brooding and get mobile and approach food. Needless to say a group of mothers fighting tends to result in trampled and dead or injured babies.
They may all bond to one hatchling or all fail to bond to any; likewise, the hatchlings may fail to bond to any one duck, or may bond to all. In this case, with chickens, they will choose the best mother and all adopt her. I don't know how ducklings would handle it.
They may become aggressive to one or all hatchlings because the hatchlings have bonded to one duck or another, or because the ducks perceive the hatchlings as belonging to another duck, irrespective of which duck the hatchling has actually bonded to... Then there's just color-hate, where a duck regardless of her own color may choose to kill all babies of a color or pattern she doesn't like. Some black hens reject all black babies and only keep whites, some white ones reject all whites and keep blacks, some mottled ones reject any non-solid-coloreds, it's crazy and apparently senseless, the reasons a baby may be rejected or killed.
These are all possibilities; there is no guarantee of what will happen, but a very high likelihood that some or all of the ducklings will die. If things go wrong, intervene immediately, would be my advice, and in future don't allow group brooding, it very rarely works.
Any help, advice, information from the point of experience would be greatly appreciated.
I haven't kept ducks, but I have kept geese, chickens, turkeys and some other birds, and from my experiences, group brooding is to be avoided unless you have two proven mothers you know can co-mother. Otherwise you're risking the whole clutch.
It's possible that some ducks co-mother well, just like some other domestic birds, but not something to bet babies' lives on if it can be avoided. It's a bit late now but fingers crossed, it may work out... But just in case I strongly recommend you have cages, makeshift if necessary, set up to isolate each duck with some eggs and a hatchling each if you have to separate them.
Best wishes, I hope you have the best case scenario occur.
