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In general, they'll keep longer because the shells are thicker. eggs spoil because bacteria get inside, or because they dehydrate... thicker shells slow down air exchange and are less likely to have open pores and cracks. unwashed eggs with the bloom on (which helps to seal the shell) keep even longer.
Before I first started supplying all my friends with duck eggs (when I had the 18-eggs a day Goldens), I had quite a surplus. I'd heard that duck eggs, especially because of their thicker shells, would keep "quite a long time" at room temp (if unwashed to leave the bloom intact.) Being an engineer, "quite a long time" was not a very satisfying bit of info.
So, I conducted The Great Egg Experiment.
I collected 4 days worth of eggs, about 60 eggs, unwashed, in standard egg cartons on my counter. After about a week, I'd check the eggs every couple of days, removing any that had darkened, or showed dark lines or cracks (signs of spoilage) or seemed particulary light (signs of dehydration). Once a week, I'd crack one or two open to see how they were doing. Here's what I learned.
Some small percentage will spoil. perhaps a dozen or so out of the 60ish eggs showed signs of spoilage or dehydrated quickly.
Some smaller percentage will lose a fair amount of moisture and dehydrate and get gummy, I think there were 5 or 6 of these. the air pocket enlarges inside the shell, the egg gets smaller and denser, basically dries out somewhat, but doesn't spoil. I don't know what the food safety folks will say, but I've got a 50-something year old cookbook that says use 'em in baking anyway if they don't smell bad or look discolored, just add cooking oil to make up the missing volume. (BTW, I *don't* use them anyway, so I don't know if that works or not. My dogs got the gummy ones. The dogs are still alive.)
The majority of the eggs were good when I cracked them. some had slightly larger air pockets inside the shells, and some had slightly less clear whites (a little foggy), but they hadn't changed color, smell, texture in any significant way. So I ate them. (not only are the dogs still alive, but so am I!)
I ran out of counter-stored eggs 4 and a half months into the process.
So, according to The Great Egg Experiment, intact unwashed duck eggs will keep on the counter 4.5 months or maybe longer.
of course you do want to check for spoilage more frequently... any that turn can become pressurized stink grenades waiting to go off when bumped.
at any rate I keep my eggs on the counter, and just rotate them so I use the older ones first. and because we eat a lot of them, there's little chance that any of them will get more than a week old.
One last thought, I've been told by a former egg-producing professional that once an egg is refrigerated, it must be kept refrigerated from then on. if it's subsequently stored at room temperature an infertile egg will spoil and a fertile one will start to develop a duckling/chick and then rot.
