apparent absorption efficiencies of nectar sugars in the cape sugarbird, with a comparison of methods.nectarivore sugar preferences and nectar composition in the cape floristic kingdom (southern africa) differ from trends reported for analogous systems in america and europe in that sugarbirds and sunbirds show no aversion to sucrose, which is the dominant nectar sugar in many of their food plants. to elucidate the physiological bases (if any) of nectarivore sugar preferences, we determined apparent sugar absorption efficiencies in a passerine endemic to this region, the cape sugarbird promerops ...20139472818
female cape sugarbirds (promerops cafer) modify egg investment both for extra-pair mates and for male tail length.the differential allocation hypothesis predicts that females should invest more in reproduction when paired with attractive males. we measured egg volume in cape sugarbirds (promerops cafer), a sexually dimorphic passerine, in relation to paternity of the offspring and in response to an experimental tail length treatment. we manipulated tail length, after pair formation, but before egg laying: males had their tails either shortened or left unmanipulated. our manipulation was designed to affect f ...201020695964
a bird pollinator shows positive frequency dependence and constancy of species choice in natural plant communities.animal pollinators mediate reproduction of many plant species. foraging theory suggests that animal pollinators exhibit preferences for common plant species in natural communities (positive frequency-dependent foraging) and temporary single-species specialization (flower constancy) during foraging bouts. positive frequency dependence may favor common plant species; flower constancy may enhance conspecific pollen transfer particularly in rare plant species. previous experimental studies suggest t ...201627870050
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