House martins are colonial urban birds that build mud nests under eaves, but nest site loss through building renovation and reduced mud availability threaten their welfare and populations.
House martin welfare in UK urban areas is threatened by nest site loss through building renovation. Birds that arrive from migration to find previous nest sites destroyed face a highly stressful nest-searching period. Colonies reduced below a critical size may not provide sufficient social cues for new birds to settle. The reduction of wet mud from waterproofed gardens and paved surfaces limits nest building material availability even where sites exist. Artificial nests remove both constraints and have a strong track record of colony establishment.