There are now four eggs in the nest. The pattern seems to be that the
bluetit arrives for the night soon after 7.00pm and spends about ¾ of an
hour turning the eggs and generally preparing for the night. The eggs must be
more robust than I thought because they get some pretty rough treatment.
We watched the whole performance last night and were surprised by the energy it
took. First there were some normal nesting wriggles. Whether she
trod on the eggs or splayed her legs to avoid them we could not see, but it
looked normal enough. Then she would stick her head between her legs to do
something to the eggs beneath her. We presume that she must be turning
them to equalise their temperature. This process is done so
enthusiastically that she often flips over on to her back! It looks
exhausting as well as undignified so presumably has a significant value - the
reasonably simultaneous hatching of her eggs. After a bit of egg turning,
she lies on top of them, resting, for a minute or so. Then the whole
process starts again.
From the evidence of the only egg we have observed being laid, she wakes up at about 5.00am and produces the egg about ½ an hour later. She then rests for a period and leaves the nest at about 5.45am. She returns occasionally during the early morning and if she can find a suitable feather or some fur, she will roughly cover the eggs. For the rest of the day she hardly visits the nest at all until the cycle begins again as the sun sets.
We presume there is another egg, but cannot tell, as our bird has concealed them. Elizabeth later put out more feathers from the old cushion, and she went into a frenzy of feather-gathering. However I was concerned about the length of time the bird was on the ground, because we occasionally have to drive away a marauding cat, so after a while Elizabeth went out and vacuumed up the remaining feathers.