Quite a bit has happened during the Eater-weekend. Here is a summary (longish) of the events:
NB-1: I think brooding has begun...it is difficult to tell, because as usual the Tree Sparrows are keen and great nest builders that never stop carrying significant amounts of nestning material into the box. Indeed a number of biggish feathers have been brought in. Some are abbandoned half-way into the nest along the entrance corridor. When this happens, the camera is blocked, or semi-blocked. At any rate the female Sparrow (I am guessing) was in the nest for an extensive amount of time this morning, which suggests that she had begun brooding. Unless of course, I was observing her attempts at laying an egg. So far, the Sparrow has not slept in the nest, which suggest one of two things:
1. Sparrows, unlike Tits (both Blue and Great) do not sleep in the nest when they have layed eggs
2. No eggs have been layed so far.
In my night-attempts at clearing the camera-view I also tried to see if there were any eggs in the nest. However, due to the complex construction of the nest, I was unsuccessful (unless of course no eggs were in the nest and thus I saw none).
Another important observation is that yesterday in the late afternoon the Sparrows mated again in the tree next to the nesting box. The mating attempts were 5-6. I am unsure as to how many of these were indeed successfull. I had already witnessed mating some 6-7 days ago. At any rate, mating means fertilising of the egg to come, i.e. the Sparrow female should be laying eggs soon afterwards. As of now the status in the nest remains unclear. When I return home this afternoon I will try to determine if a Sparrow is in the nest, and if not how much time passes before one returns to the nest. During brooding (and depending on the ambient temperature, i.e. if the temperatures are low/medium), the female leaves for only short intervals (longer ones at the beginning) for feeding. Based on the observations I should be able to determine if the Sparrow(s) (indeed I do not know if the Sparrow female alone broods or if both brood) is(are) brooding or if eggs are being layed.
NB-2: Empty (of which I am very happy). Luckly no bird-pair has taken up this nest....there have been more than enough territorial-disputes
NB-3: 9 Eggs, I believe brooding started on the 24th. She appears to have spent some time in the nest on her eggs prior to the 24th but it does not appear to have been brooding.
Egg 6 on the 22nd
Egg 7 on the 23rd
Egg 8 on the 24th
Egg 9 on the 25th
Today the male Blue Tit came repeated to bring her juicy green worms. Sometime she just starts chirping away whilst brooding, I wonder if she is calling to him for food.
The temperatures have been quite high (upper 20s) in the past few days and the temporary sun-roof seems to be helping. I hope however, that the temperatures decrease again (lower 20s). Clouds (partial) would also be good.
I measured temperatures in the nesting box again:
Date & Time | Temperature
2011.04.26 @ 11:28 | < 21.7°C
2011.04.26 @ 13:16 | 25.4°C
NB-4: On the 22nd the Great Tit female started sleeping in the nest, i.e. 1st egg was probably laid on the 22nd. I must check. Today is the 26th, so when being optimistic there could be 5 eggs in the nest as of now. I wonder how many eggs will be layed before brooding starts. Last year the Great Tits layed 12 eggs in NB-1_2010 (smaller than NB-1_2011, i.e. same sort as NB-2 to NB-4). 12 eggs is at the upper end of the range for Great Tits.
I will be posting some pictures in the next couple of days....