The Bananaquit, a Neotropical passerine nectar feeding bird, has a high protein requirement relative to other nectarivorous birds

Abstract

For nectar-feeding birds, the low amino acid and protein content of nectar is likely a major nutritional constraint. Nectar-feeding birds present morphological, behavioral, and physiological adaptations that allow them to exploit nectar efficiently. One of these adaptations might be a low nitrogen requirement compared to birds of taxa that rely on other resources. The Bananaquit (Coereba flaveola) is considered a specialized nectar-feeding passerine. It is widely distributed in the Neotropics and one of the most abundant flower-visiting passerine in northern Venezuela. We measured maintenance nitrogen requirement (MNR) and total endogenous nitrogen loss (TENL) in captive Bananaquits fed on four diets of varying concentrations of protein (0, 1.5, 3.0, and 7.0 %). We found that the Bananaquit had a MNR of 8.7 mg N day–1 (313.2 mg N W–0.75 day–1) and a TENL of 3.3 mg N day–1 (111 mg N W–0.75 day–1), values in the high range of what was previously reported for other nectar-feeding birds. However, when compared to other species with different feeding habits (i.e. granivores) the Bananaquit presents a low nitrogen requirement. These high values suggest different physiological and behavioral strategies from other nectar-feeding birds or methodological issues associated to an unbalanced diet based on a protein plant source.