Isabelline (colour) Isabelline (colour) Isabelline , also known as isabella, is a pale grey-yellow, pale fawn, pale cream-brown or parchment colour. It is primarily found in animal coat colouring, particularly plumage colour in birds and, in Europe, in horses. It also has historically been applied to fashion. The first known record of the word was in 1600 as "isabella colour"; this use later became interchangeable in literature with "isabelline" after the latter was introduced into print in 1859. The origin of the word is unclear; the uncertainty prompted by this has generated several attempts to provide an etymology and led to one
Pale crag martin 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