The House Sparrow is a cavity nester that builds a bulky, rather untidy nest of straw and feathers in cavities in buildings, under roof tiles, in gaps in facades or in nest boxes. The female usually lays 3-6 eggs, and a pair often manages two or three broods in a season. Both parents feed the young. The declining availability of suitable nest cavities in modern buildings is thought to be one of the reasons for the species' decline.