The pale crag martin was formerly often treated as the small, pale northern subspecies of the rock martin, but it is now usually considered to be a separate species. The changes in size and colour are continuous, so the evidence for separate species is not strong, although some rock martins can weigh more than twice as much as the smallest subspecies of the pale crag martin. The average weight for "P. o. fusciventris" is 22.4 g (0.79 oz) against 10 g (0.35 oz) for "P. o. obsoleta". There do not appear to be any intermediate forms where pale crag martins and rock martin populations breed close to each other in Somalia and Ethiopia.