Well, I jinxed it. In my post a week ago I wrote that it looked like a duck was going to use the East nest again but it now seems this is not going to happen. Although a wood duck laid 5 eggs and a merganser hen visited a few times (no eggs) that ended a week ago. A wood duck did visit the nest for about 2 minutes on Friday but did not stay, and except for that there was no other activity there in the past week. The five eggs are still in there and I’ll leave things as-is for a while longer, but I now doubt they’re going to go for a second round in that nest.
On the other side of the yard, the west nest hen is diligently incubating 10 eggs and there should be ducklings sometime around the 4th of July, give or take a day or a few.
It’s now clear that a duck has claimed the East nest box. There are five eggs as of today as she is in the nest for a half hour or so adding another on most mornings lately. If all goes well she will start incubating in a week or so and there will be yet another batch of ducklings about 5 weeks from now. So both nests will be used twice this year. That has happened before, but it doesn’t happen every year.
Also … a Hooded Merganser hen visited Friday morning! She didn’t leave an egg, but she rummaged around in the wood shavings like they do when sizing up a nest. We haven’t seen one for weeks, but the camera recorded her.
Thursday morning: a new egg was visible for a moment when the wood duck moved to begin covering up.
Eighteen new ducklings left the east nest this morning at 8:15. There was one unhatched egg. The new low-level camera worked well but the one inside the nest box was kind of grainy when color was turned on – I’ll take it out and test it – but it worked well enough.
I have once again edited a video, partly for those of you who could not watch live, and partly because that’s just what I do on jump day, I guess. I had my regular camera set up on a tripod in the house so the video has three camera angles: telephoto from the side, the usual camera inside the nest, and the one near the ground outside the nest box. Enjoy!
I checked the East nest this morning while the duck was out and all of the eggs on the top layer were pipped. Thus I expect hatching will occur starting tonight or early tomorrow and that would make their jump day Saturday.
Also a surprise: there are now 3 eggs in the West nest. There were none just two days ago after two weeks of brief visits, so that led me to predict in the previous post that there would not be a round two for the West nest box. I should know better. Whenever I predict something (for a good example, see the paragraph just above and the headline of this posting) the ducks like to fool me. I should just stop doing that and instead always write “we’ll see” instead.
The last stages of hatching occur when the duckling uses its “egg tooth” to break through the egg membrane into an air pocket that forms in the egg between the membrane and the shell. At this time the egg white has been fully absorbed and the yolk is becoming internalized in the duckling, so there’s no free moisture inside. The duckling breathes in this air pocket and there is some air exchange through the shell, which is porous.
A while later the duckling adds to the air exchange by pecking at the egg shell in one spot (wherever its little beak is), which is called pipping the egg shell. That lets in more air.
Since the duckling is breathing it can make sound and I’ve heard faint peeping when holding a pipped egg. I think this stimulates the hen to be even more active than usual in turning the eggs. Hours later, about a day or so after pipping, the duckling has developed enough to use its legs to push and to very slowly rotate inside the egg as it pecks with its egg tooth. It takes many hours to break the egg all the way around and to finally emerge. The egg tooth is a sharp spur at the end of the ducklings bill. You can see it as a white spot after they hatch:
I just now (4:30 CDT) checked 10 of the 19 eggs (I didn’t dig through all of them) and none of them were pipped. The ducklings will “pip” the eggs – crack them slightly in one spot – about 24 hours before they hatch. Some sites say 24 to 48. So I’d estimate the earliest hatching day at this point as Thursday and jump day no sooner than Friday. It could be into the weekend.
Estimating the start of incubation is something of a guess: is she actually incubating (heating) the eggs, or just resting in the nest box? Then the incubation time also varies: it’s nominally 30 days but that’s plus or minus two or three. The east nest is apparently going to the plus side.
The ducks have stopped visiting the west nest box and there aren’t any eggs in there. One year we had two batches in both nest boxes: 70+ ducklings! But it looks like this year it will be one hatching for each.
(A duck continues to rest in the now-empty west nest box for a while most mornings with the male in attendance outside. That is egg-laying behavior so we’re hoping for “round 2” in that nest. That has happened in the past but so far no eggs as of today.)
I set up the outdoor camera in its new enclosure (see the May 20 post) beneath the east nest box today. It is live already. I put it out ahead of the probable jump day – Monday plus-or-minus a day or a few – so the duck gets used to it and I figured might as well hook it up and turn it on. I was going to put it right down on the ground but the hostas have sprung up so I elevated it by a foot to give it a better view. Below are examples of the views that it has. (There are 4 images – if you see only one try scrolling the gallery sideways.) For now I’m leaving the camera turned to the creek so that if you take a look you might see a mallard or wood duck drifting by.
All of the cameras are linked from the birdsgv.com home page of course, but for convenience here are the same links for the East nest.