Nectar sugar preferences and absorption in a generalist African frugivore, the Cape White-eye Zosterops pallidus

Sugar preferences and absorption efficiencies were investigated in the Cape White-eye Zosterops pallidus, a generalist frugivore, Unlike the mainly American frugivorous passerines previously studied, Cape White-eyes preferred 20% (weight:weight) solutions of sucrose to glucose or fructose, and apparently possess high sucrase activity because absorption efficiencies for all three sugars were close to 100%. Cape White-eyes rejected 20% solutions containing a fourth nectar sugar, xylose, recently found in the nectar of Protea and Faurea (Proteaceae), Absorption efficiencies for xylose averaged 61%, but we do not know whether this sugar is utilized by the birds, Cape White-eyes thus resemble specialized southern African nectarivores (Nectariniidae, Promeropidae) in their responses to nectar sugars.