Size of black patches and spots on the upperwing and underwing greater secondary coverts in selected feathers are not good indicators of age and sex in Cape Vultures Gyps coprotheres

Abstract

Cape Vultures Gyps coprotheres have black patches on their upperwing greater secondary coverts and black spots on their underwing greater secondary coverts. These have been physically observed to differ with individuals. This study examined the effects of age in years and sex on the size of the patches and spots using computer feather image analysis of birds with known ages in order account for differences that pure observation alone could possibly miss. Despite statistical analysis of computer enhanced imagery of micro detail the chosen plumage pattern failed to yield a reliable way to age and sex Cape Vultures. Annual moult is not expected in this species making the correlation of moult to age a muddle as it is also influenced by external factors such as captivity, stress, food, endocrine (sexual changes), and latitude. This study was limited by the lack of understanding of the exact moulting sequence of upperwing and underwing greater secondary coverts of the Cape Vulture, and as a direct result of this, analysis of the chosen plumage was maintained instead of the feather that is moulted in that particular year.