Many of our nesting birds are synchronous hatchers. The birds all hatch at the same time and thus are ready to leave the nest at the same time. Generally (perhaps always) a hen lays only one egg at a time, usually once a day with the ducks. Sometimes, it is once a week, with some birds, like owls and raptors. If the hen incubates the egg upon laying it, the clutch will hatch asynchronously. If she lays one egg a week, the eggs will hatch one week apart and the nestlings will be at different stages of development and sizes in the nest. With our ducks and passarines the eggs are laid and when the hen is finished laying she will start incubating so the eggs will start developing at the same rate and be ready to hatch and leave the nest at essentially the same time. This means that a clutch of eggs will be left unattended until the hen stops laying and starts incubating. Since the hens are usually pretty secretive about entering the nest to lay eggs, it may appear that the nest is unattended and abandoned. The eggs are hardy and can withstand normally cold nights without being incubating, even if the temperatures drop below freezing.
Wood Ducks normally lay clutches between 10 to 15 eggs, although the clutches can range from 6 to 15. So my nest with 18 eggs show that at least three hens are laying in this box. In all probability, we have at least four. Last year, I estimated the number of eggs in this box at 28 or more. In a dump box like this occasionally two hens will incubate at the same time. The hens are hypothesized to be closely related, but this may not be the case. They may not even be the same species. If the clutch is destroyed before they hatch, some birds will nest a second time with less eggs. I have had late nesting hens in some of my boxes that have already had a hatch. Since I am not monitoring the boxes close enough to know how many eggs have not hatched, I have no way to estimate the clutch size of the second hatch, but late clutches on the lake are smaller than the earlier clutches. Steve Weston On Quigley Lake in Eagan, MN swest...@comcast.net On Thu, Apr 18, 2019 at 12:01 PM Steve Weston <swesto...@gmail.com> wrote: > Last week we had good birds feeding in the yard on the seed I scattered > out: about 20 Juncos, 2 Fox Sparrows, 2 Tree Sparrows, and a Song Sparrow. > Yesterday I had a Swamp Sparrow and today we had a Hermit Thrush. > > Checked 3 of the 4 wood duck houses. > 1) 18 eggs including 1 Hooded Merganser > 2) 9 eggs all appeared to be Woodies > 3) None. I think I will replace that one this year > > I also noticed one egg broken near the popular house. I assume that there > was too much traffic for the hen to get into the house before she dropped > her egg. > > About 3 days ago I first noticed that the chorus frogs were singing. > > Steve Weston > On Quigley Lake in Eagan, MN > swest...@comcast.net > ---- Join or Leave mou-net: http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net Archives: http://lists.umn.edu/archives/mou-net.html
