Blue tits can be found almost everywhere, but their main habitat are woodlands. They prefer mixed or deciduous forests and will use holes in trees that are small enough to stop predators from raiding their nest. They will also use garden nest boxes with the right sized hole. The male and female are similar, with the female being just a bit duller in colour. They nest from mid April till early May, laying 6-12 eggs in a cup-shaped nest made from grass, leaves, moss and lined with hair, feathers and down. The eggs are laid at daily intervals, and if the female leaves the nest she will cover the eggs with the lining of the nest to keep them warm. When she has finished laying the chicks will hatch after an incubation of 12-15 days. The eggs are blue-green with brown speckles. The chicks will stay in the nest for a further 2-3 weeks, being fed by both adults on food from garden bird tables, but their main diet is caterpillars, aphids and small vertebrae. The chicks have a yellow face that will turn white when they become adults with the distinctive blue cap.