I have been away for a week ca. and therefore unable to keep up-to-date with events.
When I got back yesterday I found out:
1. In the office nesting box (NB-3) 1 egg had been laid. I presume this was laid in the morning of the 16.04.2011. This morning however, the egg was covered, so I could not see if there are 2 by now.
2. In the large nesting box (NB-1) the Tree Sparrows build a nesting by using a large amount of material...it is pretty amazing actually. They covered the entire surface with nesting material and thus brought the floor to a height which is now about 1-2 cm below the entrance hole. The entrance to the nest itself is on the farside of the box. The nest floor is lower than the surrounding floor and the nest is covered on the top. The inner nest volume thus assumes a spherical shape and 3/4ths of its surface area is covered with material.
3. The Great Tit female with the spot on her head (the one that lost the large nesting box to the Sparrows) has started building a nest in the smaller nesting box (NB-2). I am happy that she has taken up this second nesting box.
Due to the fact that the sparrow nest is so complex, and due to the fact that so much material was carried inside the box, 2 of the 3 cameras are completely covered in material and no longer have optical access to the nest. The 3rd camera mounted on the top has a very reduced optical access (less than 1/4th). Last night we therefore (after sunset) made a blitz modification (ca. 1 hour) to the nesting box and added a 4th camera to the box. The camera is mounted from the outside and allows a partial view of the nest. Although I will probably not be able to see how many eggs will be laid, I will hopefully be able to follow the general developments.