The house martin is a familiar summer visitor that builds mud nests under the eaves of buildings, yet its population has declined significantly as aerial insect prey has decreased and traditional nesting sites have been lost to building renovation.
House martin welfare is threatened by declining aerial insect availability driven by insecticide use and habitat changes reducing small fly and aphid populations. Building renovation that fills or removes eave overhangs destroys colonies that have used the same sites for decades. Planning authorities sometimes require artificial house martin nests to be installed in new buildings but monitoring of use rates is poor. The unknown wintering grounds make assessing non-breeding welfare impossible.