Tree Sparrow Male-Female Cooperation and Strangeness in NB-4

Unfortunately I am not abel to follow the events which might be unfolding in NB-3 (it being at work).

I have however discovered to my great surprise, that not only do the Tree Sparrows bild the nest together, they also take care of the eggs together. I am unsure as to whether both female and male brood (the nest construction had seriously limited by optical access) but at least they take turns at being in the nest.

I just noticed that one of the Tree Sparrows entered the nesting box, chirped, there was then a serious chirp-conversation and then the bird in the nest left to be replaced by the other that had just entered. This second bird then gave one quick peak out of the nesting box and then returned to the nest.

What I find really funny is that when it entered the nest and adjusted itself, it chirped a bit until it had settled. Sparrows are indeed completely different to Tits in their behaviour both as individual birds as well as in pairs. They are definitely more "outspoken".

Now a little update in NB-4: the female Great Tit spends her days in the nest. I am not sure what is going on, and I wonder if for some reason she is unable to lay eggs. I cannot image that she is simply the whole time just sitting there, guarding and empty nest. Then again, there might be the possibility that she had indeed laid eggs and that these are incredible well hidden. This would however surpise me because it would imply that she broods without uncovering the eggs, which is altogether very strange. Her first night in the box was the 22nd of April and by now she should have laid more than enough eggs really. If I assume 10 eggs, this would lead to the 2-3rd of May, so in theory she would now be in her 3rd day of brooding. The male Great Tit still feeds her regularly. I am curious as to how this will all evolve.

It was about 8:15 when I noticed the Tree Sparrows switching places. At 8:32 they switched again. Now again, I wonder: on the 26th of April, one of the Sparrows, spent the first night in the nest (I presume the female, but I may be 50% wrong! which is a huge error range in my books :-)) now again: on the 26th the first egg might have been laid, by now there should be a sufficient number of eggs in NB-1. Given this switching, I presume that now brooding has indeed begun. Previously, I had noticed that there were gaps of time in which no bird was in the nest. If this is so, i.e. brodding, then (assuming ca. 8 eggs) then brooding has started ca. 3-4 days ago and thus there are still 2.5 weeks to go until I hear tiny high-pitched chirping.

One this is sure: I am going to have to conceive a new nesting-box concept with which I am easily move my camera(s) around (perhaps finger cameras?). I am thinking hard already. As soon as the season is over and the birds have left (such that I have gathered enough information to know how the different phases: nest building/egg laying/brodding/hatchlings, modify my optical access requirements) I will start developing version 3 of the nesting box.