There are at least 2 hatchlings in NB-1! I am so beyond happy, as I managed to catch a good glimpse of the two hungry hatchlings this afteroon. My last minute adaptations, i.e. side camera addition post-nest-building-completion, seem to have been successfull, and although I was not able to follow the egg laying process and the brooding in detail, I will be able to see the hatchlings develop afterall!
I guess the worm-transport last Sunday was already part of the feeding. By looking at the live stream they appear to be ca. 1.5 week old. However, the eyes are not open yet and they do not have many feathers on their heads. I heard chirping on Monday evening for the first time. I thus assumed that the eggs had hatched on Monday. If indeed there are only 2 hatchlings, these will grow (and will have grown) much faster than the 7+ Blue/Great Tit hatchlings. It takes Tit hatchlings ca. 3 weeks before they leave the nest, I am curious to see how long before the Sparrows take flight.
At work on Wednesday there were still 8 hatchlings alive though 2 were quite a bit smaller. I wish I could see how they are coming along. I hope they are still all there on Monday.