Sand martins are early migrants that breed in large colonies in sandy riverbanks and quarry faces. They are vulnerable to bank erosion, river management, and Sahel droughts that affect their survival on the wintering grounds.
River management that removes or stabilises sandy banks destroys entire colonies in a single operation. Burrows containing eggs or chicks are sealed or collapsed, causing the death of all young and disorientation of returning adults. Sahel droughts that kill large proportions of overwintering birds reduce colony sizes dramatically the following breeding season. Quarry operators who accidentally destroy colonies during extraction face birds attempting to re-establish in unsafe locations with continued disturbance.