The Réunion grey white-eye (Zosterops borbonicus) is a small passerine from the family Zosteropidae,[1] which is native to the islands of Réunion.[2]
The taxon mauritianus, by most authorities previously considered a subspecies, is now usually considered a separate monotypic species, the Mauritius grey white-eye, (Zosterops mauritianus). Together, both species were called Mascarene white-eye.[3]
There is some uncertainty about the number of subspecies on Réunion, with most authorities only accepting a single, the nominate (Z. b. borbonicus), while some also accept Z. b. alopekion, and Z. b. xerophilus. When only a single Réunion subspecies is accepted, alopekion and xerophilus are considered to represent morphs of the nominate.
It has a length of 9.5 cm. Its plumage exhibits colour morphs which vary from gray to brown. The tail coverts are conspicuously white, unlike those of the Réunion olive white-eye. The rest of the body plumage is variable in hue, though invariably lighter than that of the previous species.[4] It is typically blue-grey with a brownish wash to the mantle, and distinctly rufous-brown flanks. It has chestnut-coloured eyes with a very indistinct eye-ring, as opposed to that of the Réunion olive white-eye. In both species the breast and flank feathers create a white "epaulette" effect.[4]
It inhabits woodlands, forests, and gardens. It is the only endemic bird from Réunion which has adapted to man-made conditions. Its diet consists of insects, fruits and nectar. It is also the pollinator for orchids like Angraecum striatum or the endemic Trochetia species. It moves often in small groups from six to twenty birds in search of food. They are very noisy. The breeding period is in the southern summer. The female lays two to four pale blue eggs in a cup-shaped nest which is padded with plant material.