House sparrow populations have crashed in many European cities, with London losing over 70% of its sparrows since the 1990s. Understanding what drives this decline is critical for welfare-focused conservation.
Urban sparrows face multiple simultaneous stressors: food scarcity, loss of nesting sites, reduced invertebrate availability, and predation pressure from cats and sparrowhawks. Isolated individuals separated from colonies suffer significant social stress as they are highly group-dependent. Injured sparrows in urban areas often fail to access appropriate food while recovering.