altitude, although Eric Simms reported nests at heights from . Firecrests may favour breeding close to northern goshawk nests. That large bird will prey on potential predators of the firecrest such as Eurasian sparrowhawks, and nest robbers like grey squirrels, Eurasian jays and great spotted woodpeckers. As is typical for the family, the nest is a closed cup built in three layers with a small entrance hole near its top. The nest's outer layer is made from moss, small twigs, cobwebs and lichen, the spider webs also being used to attach the nest to the thin branches that support it. The middle layer is moss, and this is lined with feathers (up to 3,000) and hair. The nest is smaller, deeper and more compact than that of the goldcrest, about across and deep, with a wall thickness of about . The nest is constructed by the female alone, although the male will accompany the female while she builds the nest over a period of a few days to three weeks. Laying starts in western Europe at the end of April, and in the east of the range in late May; second clutches, which are common, commence in June to July. The eggs are pink with very indistinct reddish markings at the broad end, unlike those of Madeira firecrest which are described as like those of a Phylloscopus warbler (white with some brown speckles). The eggs are and weigh , of which 5% is shell. The clutch size in Europe is 7–12 eggs, but probably smaller in northwest Africa. The female incubates the eggs for 14.5 to 16.5 days to hatching, and broods the chicks, which fledge eight to ten days later. Both parents feed the chicks and fledged young. This species becomes sexually mature after one year, and has a life expectancy of less than two years. Although their ranges overlap substantially, hybridisation between goldcrests and firecrests seems to be prevented by differences in courtship rituals and different facial patterns. Even in aviary studies in which a female goldcrest was given an artificial eyestripe to facilitate mating with a male firecrest, the chicks were never raised by the mixed pair, and appeared to be poorly adapted compared to the parent species. Feeding All species of kinglet are almost exclusively insectivorous, preying on small arthropods with soft cuticles, such as springtails, aphids and spiders. They also feed on the cocoons and