Plant Systematics and Evolution

, Volume 238, Issue 1–4, pp 139–153

Nectar as food for birds: the physiological consequences of drinking dilute sugar solutions

  • S. W. Nicolson
  • P. A. Fleming

DOI: 10.1007/s00606-003-0276-7

Cite this article as:
Nicolson, S. & Fleming, P. Plant Syst Evol (2003) 238: 139. doi:10.1007/s00606-003-0276-7


 Nectarivory has evolved many times in birds: although best known in hummingbirds, sunbirds and honeyeaters, it also occurs on an opportunistic basis in a varied assortment of birds. We present a phylogenetic analysis of the distribution of nectarivory in birds. Specialised avian nectarivores are generally small, with an energetic lifestyle and high metabolic rates. Their high degree of dependence on nectar as a food source has led to convergence in morphological, physiological and behavioural adaptations. We examine the constituents of nectar which are most important to bird consumers, and how the birds deal with them in terms of physiology and behaviour. There are still unanswered questions: for example, the dichotomy between sucrose-rich nectars in hummingbird-pollinated plants and predominantly hexose-rich nectars in sunbird-pollinated plants appears to have little to do with bird physiologies and may rather reflect patterns of nectar secretion.

Key words: Nectarivory, pollination, hummingbirds, sunbirds, sugar digestion, water balance, osmoregulation. 

Copyright information

© Springer-Verlag Wien 2003

Authors and Affiliations

  • S. W. Nicolson
    • 1
  • P. A. Fleming
    • 1
  1. 1.Department of Zoology and Entomology, University of Pretoria, Pretoria, South AfricaSouth Africa

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