Barbears House 
Five baby Blue Tits in a row
Blue Tits breed wherever there are areas of trees with suitable nest holes. They start looking for nesting sites about February, preferring small holes or narrow cracks in trees about 1 - 15 metres from the ground. Nest boxes in gardens are readily used, especially if there is a shortage of natural sites in an area. Both males and females search for nest holes, but when the male finds somewhere suitable, he displays by fluttering his wings and calling to his mate; he will then go into the hole, calling the female and hoping she will follow and approve the site. She doesn't always approve it and may reject several before deciding on the one she wants!

The female must be of a reasonable weight prior to laying to ensure she survives and during the rearing of large broods she can lose between 15 and 36% of her body weight.

She builds the nest alone, collecting moss, dried grass, dead leaves and wool to fill the bottom of the nest hole; she forms a cup-shaped structure with this material and finally lines it with soft feathers or hair. A clutch of 7 - 13 eggs is laid from mid-April to early May. The eggs are white with reddish-brown speckling and are laid at the rate of one a day. Incubation begins only when the clutch is almost complete to ensure they all hatch around the same time - the female usually covers the eggs with some nest lining if she has to leave them for a while. Incubation lasts almost two weeks and whilst the female is sitting on the eggs, the male defends the area around the nest site from other Blue Tits, so protecting the available food needed for both adults and, later, the young. He also brings food to his mate.

The young hatch at a time when food is at its most abundant. They are fed by both parents, mainly on small caterpillars, but in our case we have a large Silver Birch tree which provides a ready supply of greenfly. The young remain in the nest for around two or three weeks. The adults also remove the droppings regularly, to keep the nest clean.

The exciting time comes as one of the young birds, often the most advanced decides it is time to move out and at first hangs from the inside of the nest box and looks out through the hole for the parents. Eventually, with some encouragement from Mum and Dad it will take that leap of faith into the big world beyond, hopefully getting some flying practice at the same time. Soon after others will follow and the parents will do less and less feeding in the nest to encourage this process. Hopefully all the birds leave, but there is a real risk that the last one is so weakened by the food reduction they it will never leave the nest and die from neglect.

They are then fed in the garden for a while, often huddling together as in the picture above in the day and hiding during the night, but one by one they depart and we lose track of the youngsters. We can only hope that they survive. So, how many will likely survive to adulthood, the answer is that only about 10-20% of young reach adulthood. Those that do generally live for just over a year, but some can live longer, at least one has been known to live for 21 years!