Has Spring arrived at last?

Tonight, for the first night this year, no bird is sleeping in the nesting box. 

This happens when (a) the temperatures are high enough, and (b) when the birds start building nests. As these two generally happen at the same time, it is kind of hard to tell which one is the forcing factor. 

Today, a male and a female Great Tit examined both this nesting box (wood-concrete) and the wooden one out the front of the garden.  

I must say that nesting-box-apartment-search-time is one of my favourite! The birds engage in both searching, examining, courting rituals,...the calls...the movements, the careful examinations, the careful observing of the surroundings. It is one magnificent display and I could just watch for hours.