Do the late ducklings die? In the wild, yes they do. This has made people upset and sad. I feel that way too. However it is a normal part of nature: little birds that hatch but are too late do not survive.

Late ducklings can survive if they are lucky enough to be left behind in the small fraction of nests that have a camera, so that somebody knows, and that are attended by someone who can get there in time.  The place that late ducklings here can go near here is The Wildlife Rehabilitation Center of Minnesota. They will take ducklings, but not unhatched eggs.

Why do they hatch too late? When the incubating hen starts to keep the eggs warm they all start developing at that time. They stay dormant until then. So even though the first one has been in the nest for about two weeks longer than the most recent one, they all start developing at the same time and they all hatch together about 30 days later.  

Other wood ducks will lay eggs in the incubating duck's nest. This is called "dumping", really, that's the bioligist's name for it. It's a survival strategy: by dumping an egg in another nest a duck may have descendents that survive even if she doesn't. If it's going to work it has to be dumped before incubation starts of course, so that it hatches with the others. But other ducks will dump eggs even after incubation has begun and these will not hatch with the others. 

So ... let's say an egg is dumped in a nest after incubation has started but not too long after: then that duckling might hatch many hours after the others. It takes about 24 hours for a duckling to get strong enough to climb, jump, swim, and follow the mother. If a duckling hatches too late it won't be as developed as the others when they are ready to leave the nest and it won't be strong enough to go.

This is part of how wood ducks are and always have been. The sad fate of late ducklings occurs in thousands of nests every spring and it has been that way for tens of thousands of years. The difference between nest boxes such as mine and the vastly more numerous other nest sites is that a camera is in the nest box so you and I can see what happens and at least try to save a few late ducklings. But for the vastly more numerous wild nests, the late ducklings die. 

If it helps, the harshness of nature is mellowed just a bit by how the ducklings respond. Once the others have left the nest those that are left behind pretty much just shut down. They don't peep. They don't struggle or thrash around. They don't move very much or very often. I like to think this is by nature's design: if they aren't going to survive, at least they can be sleepy and go out peacefully.