, Volume 60, Issue 2, pp 214–226 | Cite as

Mechanical determinants of nectar feeding strategy in hummingbirds: energetics, tongue morphology, and licking behavior

  • Joel G. Kingsolver
  • Thomas L. Daniel
Original Papers


To explore the mechanical determinants of feeding strategies for nectar feeders, we develop a fluid dynamical and behavioral model describing the mechanics and energetics of capillary feeding in hummingbirds. Behavioral and morphological data for Calypte and Archilochus are used to test and illustrate this model. We emphasize the important differences between capillary and suction mechanisms of fluid feeding. Model predictions of nectar intake rates and nectar volumes per lick are consistent with observed values for Calypte anna. The optimal nectar concentration maximizing rate of energy intake depends on tongue morphology and licking behavior. For hummingbirds exhibiting optimal licking behavior, the optimal nectar concentration is 35–40% sucrose for feeding on large nectar volumes. For small nectar volumes, the optimal concentration is 20–25%. The model also identifies certain tongue morphologies and licking frequencies maximizing energy intake, that are consistent with available observations on licking behavior and tongue design in nectar feeding birds. These predictions differ qualitatively from previous results for suction feeding in butterflies.

The model predicts that there is a critical food canal radius above which suction feeding is superior to capillary feeding in maximizing the rate of energy intake; the tongues of most hummingbirds and sunbirds fall above this critical radius. The development of suction feeding by nectarivorous birds may be constrained by the elastic properties of their flexible tongues. Our results show that, in terms of morphology, scaling, and energetics, different mechanisms of feeding on the same food resource can lead to qualitatively different predictions about optimal design and feeding strategies.


Nectar Volume Food Canal Feeding Bird Suction Feeding Nectar Feeding 
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  1. Adamson A (1963) Physical Chemistry of Surfaces. John Wiley and Sons, New YorkGoogle Scholar
  2. Baker HG (1975) Sugar concentration in nectars from hummingbird flowers. Biotropica 7:37–41Google Scholar
  3. Baker HG (1978) Chemical aspects of the pollination biology of woody plants in the tropics. In Tropical Trees as Living Systems. Cambridge U. Press, Cambridge, pp 57–82Google Scholar
  4. Baker I, Baker HG (1982) Some constituents of floral nectars of Erythrina in relation to pollinators and systemtics. Allertonia 4:25–37Google Scholar
  5. Bird RB, Stewart WE, Lightfoot EN (1960) Transport Phenomena. John Wiley and Sons, New YorkGoogle Scholar
  6. Bolten AB, Feinsinger P (1978) Why do hummingbird flowers secrete dilute nectars? Biotropica 10:307–310Google Scholar
  7. Calder WA (1979) On the temperature-dependency of optimal nectar concentrations for birds. J Theor Biol 78:185–196Google Scholar
  8. Charnov EL (1976) Optimal foraging, the marginal value theorem. Theor Pop Biol 9:129–136Google Scholar
  9. Crisp JD (1972) Properties of tendon and skin. In: Biomechanics: Its Foundations and Objectives. Prentice-Hall, New Jersey, pp 141–179Google Scholar
  10. Daniel TL, Kingsolver JG (in press) Feeding strategy and the mechanics of blood sucking in insects. J Theor BiolGoogle Scholar
  11. Davies JT, Rideal EK (1979) Interfacial Phenomena. Academic Press, New YorkGoogle Scholar
  12. Ewald PW, Williams WA (1982) Function of the bill and tongue in nectar uptake by hummingbirds. Auk 99:573–576Google Scholar
  13. Feinsinger P, Wolfe JA, Swarm LA (1982) Island ecology: reduced hummingbird diversity and the pollination biology of plants, Trinidad and Tobago, West Indies. Ecology 63:494–506Google Scholar
  14. Hainsworth FR (1973) On the tongue of a hummingbird: its role in the rate and energetics of feeding. Comp Biochem Physiol 46:65–78Google Scholar
  15. Hainsworth FR, Wolf LL (1976) Nectar characteristics and food selection by hummingbirds. Oecologia (Berlin) 25:101–113Google Scholar
  16. Heyneman A (1983) Optimal sugar concentrations of floral nectars-dependence on nectar energy flux and pollinator foraging costs. Oecologia (Berlin) 60:198–213Google Scholar
  17. Kingsolver JG, Daniel TL (1979) On the mechanics and energetics of nectar feeding in butterflies. J Theor Biol 76:167–179Google Scholar
  18. Kresch E, Noordergraaf A (1972) Cross-sectional shape of collapsible tubes. Biophysical Journal 12:274–294Google Scholar
  19. Pyke GH, Pulliam HR, Charnov EL (1977) Optimal foraging: a selective review of theory and tests. Quart Rev Biol 52:137–154Google Scholar
  20. Pyke GH, Waser NM (1981) The production of dilute nectars by hummingbird and honeyeater flowers. Biotropica 13:260–270Google Scholar
  21. Schlamowitz RF, Hainsworth FR, Wolf LL (1976) On the tongues of sunbirds. Condor 78:104–107Google Scholar
  22. Schoener TW (1971) Theory of feeding strategies. Ann Rev Ecol Syst 2:369–404Google Scholar
  23. Snodgrass RF (1954) Principles of Insect Morphology. McGraw-Hill, New YorkGoogle Scholar
  24. Stokes RH, Mills R (1965) Viscosity of Electrolytes and Related Properties. Pergammon Press, OxfordGoogle Scholar
  25. Sutherland S (in prep) Nectar concentration in hummingbird flowers: maximizing the instantaneous rate of energy intakeGoogle Scholar
  26. Vogel S (1981) Life in Moving Fluids. Willard Grant Press, BostonGoogle Scholar
  27. Wainwright SA, Biggs WD, Currey JD, Gosline JM (1976) Mechanical Design in Organisms. Halsted Press, New YorkGoogle Scholar
  28. Weymouth R, Lasiewski R, Berger A (1964) The tongue apparatus in hummingbirds. Acta Anat 58:252–270Google Scholar

Copyright information

© Springer-Verlag 1983

Authors and Affiliations

  • Joel G. Kingsolver
    • 1
  • Thomas L. Daniel
    • 2
  1. 1.Department of ZoologyUniversity of CaliforniaBerkeleyUSA
  2. 2.Department of ZoologyDuke UniversityDurhamUSA

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