Sandy McRuer wrote:

"We were surprised to find that 3 out of 4 had nest material in them. It was mainly Kindbergia moss, but also there was what looked roughly like potting soil complete with tiny pieces of mica. In addition, two had egg shell remnants in them. The original eggs appeared to be a little smaller than a golf ball and a light brown or beige colour. The fifth box was left alone because it had four similar eggs in them. If these are wood duck eggs, they are nesting earlier than suggested in the Birds of BC. And also the evidence seems to contradict the literature which told me that Wood Ducks do not bring nest material to the nest. Can anybody tell me if any other cavity nesting species have brown eggs and bring nest material to the nest?"

Sandy,

It sounds from your description of the eggs - smaller than wood duck eggs, 'round' rather than
'egg-shaped' - that you are looking at the eggs of the W Screech-Owl. The owl eggs are white
when fresh, rather than brown, but the pigment might come from staining (?). Wood duck eggs,
of course, tend to be a buff and those of the Hooded Merganser are more grayish-white.

These owls often nest considerably earlier than do the woodies or hooded mergansers (the
other bird that regularly uses wood duck boxes). Bent (1938) gives egg dates in mid-to-late
March, and Jewett et al. (1953) notes that 2-4 eggs of Otus asio kennicottii are laid from
"April 7 to May 15". So, this is about when you should expect to find screech owl eggs.

I don't know what to make of the moss in the nest. Bent writes: "I believe that they never carry
in any nesting material and that where such material is found it merely indicates that some
other bird or mammal had brought it there previously." I checked several wood-duck boxes in
Oregon years ago, and never found nesting material in the boxes (we cleaned the old duck
nesting material out every year) that had nesting owls.

Perhaps the chickarees (Tamiasciurus douglasi) or a flying squirrel had brought in the moss?
Another possibility is that of bees; in my Olympia suburban wasteland of a yard, there is a
species of native bumblebee that fills the wren/chickadee-nesting boxes I've put up with tree
moss. Anyway, if there was moss in a cavity, it shouldn't preclude an owl from nesting on top
of the material.

Keep in mind that wood ducks, while not necessarily *bringing* material to the nest cavity, will
often fill the base of the cavity with their own down. Over the years, this material, along with
the 'sawdust', can compost down into a type of 'soil'. Otherwise, few of the large cavity-nesters
tend to bring nesting materials into the cavity.

Just a couple of suggestions...

Jon. Anderson
Olympia, Washington
festuca at olywa.net