HD Oschadleus. Iris colours in ageing and sexing South African Ploceus weavers. Afring News 40:7-12

Eye colours can be quite striking in some weavers. A calculation shows that globally in weavers the distribution of eye colour is 78% brown, 21% pale, and 10% red. Knowing the eye colours of all age and sex groups can prevent errors in ageing and sexing weavers in the hand by ringers. For the eight Ploceus species studied here, adult males have coloured eyes in summer and in winter, although they may be less bright in winter (more data is needed for Southern Brown-throated Weavers in winter). Adult females of Golden, Spectacled and Lesser Masked Weavers appear to have pale eyes in adults of both sexes year round. In the other species, varying proportions of the adult females have pale or red eyes in summer, and even less individuals have coloured eyes in winter. Juveniles have dark brown eyes in all species and in some species this colour lightens after several months in males. Using only eye colours is thus unreliable for ageing and sexing South African Ploceus weavers.

Read the article here and other weaver identification papers here.
Photo: pale eye of the male Spectacled Weaver.