Nature Done Wright

Incorporating the Celery Farm and Screech Owl Companion blogs

April 19, 2007

The case of the missing egg

First things first: Mrs. Ace update

Thanks to the screech cam, I can report that she is doing well.

She stills sits on the four eggs most of the time.

She still whinnies as dusk approaches.

And she still takes a brief flight just after dark — presumably to eat.

Which brings us to the crucial word in trying to write about screechers, with or without a screech-cam — presumably — and which brings up a mystery.

One of the concerns I have in writing this blog is that I watch the screech cam in my owl box, and then (erroneously) presume that what I see applies to screech owls in general.

So I was interested to come across some photos and comments by a birder who has a screech owl cam in Central New Jersey. http://www.flickr.com/photos/sw1/

Steven Weiss reported two things of note: that the male and female are sharing the owl box, and that the owl count — which had reached four — was down to three.

I believe that the owls sharing the box is common. One reason for sharing might be a dearth of other suitable places. Another might be that some owls just prefer it.

As for the missing egg, Weiss writes that last year the egg count went from three to one overnight. His theory:

"Last year, I had the camera installed before the owls began nesting. All I ever saw leave and enter the box was a red owl. I can’t be certain, but thought that the male had a new mate.

"If you watch the owls when they enter the box, they usually pop their heads in, look down at the nest and kind of ‘drop’ to the bottom. So, without ever seeing a predator, I felt that an inexperienced female might have broken the eggs entering the box."

Weiss adds that he "would think that this season’s lost egg would also be an accident, possibly broken by one (or both) of the adults when moving about in the box.

"Still, the possibility of a predator is possible. Since there is no since of disturbance of the other eggs, nor any egg shells in or about the nestbox, a possible predator could be a snake.

"In any case, I hope the remaining eggs make it through the next three to four weeks of incubation."
I am going to e-mail a few owl experts and see if they have come across this — and what they think the cause is.
If you have a theory, please let me know.