House sparrows have declined by 60% in the UK since the 1970s with the steepest declines in urban areas, where loss of nesting sites in buildings and reduction in invertebrate food for chicks are primary drivers.
House sparrow welfare in urban areas is threatened by the gradual removal of nesting sites through building modernisation and the reduction of insect prey availability through increased paving and reduced plant diversity. The cumulative effect of many small changes to urban structure has made cities progressively less suitable for sparrows despite superficial continuity of their presence.