is a well-insulated cup-shaped structure built in three layers. The nest's outer layer is made from moss, small twigs, cobwebs and lichen, the cobwebs also being used to attach the nest to the thin branches that support it. The middle layer is moss, which is lined by an inner layer of feathers and hair. The nest is larger, shallower and less compact than that of the firecrest, with an internal diameter of about , and is constructed by both sexes, although the female does most of the work. It is often suspended from a hanging branch, usually at no great height, although Eric Simms reported nests at heights from . One pair built their nest just above that of a sparrowhawk. Laying starts at the end of April into early May. The eggs are whitish with very indistinct buff, grey or brown markings at the broad end. The eggs are and weigh , of which 5% is shell. The clutch size in Europe is typically 9–11 eggs, but ranges from 6–13. The eggs are piled up in the nest and the female keeps the eggs warm with her brood patch and also by putting her warm legs into the middle of the pile between the eggs. Within a clutch the size of eggs increases gradually and the last laid egg may be 20% larger than the first egg. Second clutches, which are common, are laid usually while the first nest still has young. The male builds the second nest, then feeds the young in the first nest while the female is incubating in the second; when the first brood has fledged, he joins the female in feeding the second brood. The female goldcrest is not normally fed by her mate while incubating. She is a tight sitter, reluctant to leave the nest when disturbed, and has been recorded as continuing to attend the nest when it has been moved, or even when it is being held. The eggs are maintained at , the female regulating the temperature of the eggs by varying the time spent sitting. She leaves the nest more with increasing air temperature, and incubates more tightly when the light intensity is lower early and late in the day. The female incubates the eggs for 16 to 19 days to hatching, and broods the chicks, which fledge in a further 17 to 22 days later. Both parents feed