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Article
Hummingbirds Fuel Hovering Flight with Newly Ingested Sugar
Physiological and Biochemical Zoology
  • K. C Welch
  • B. H Bakken
  • Carlos Martinez del Rio, University of Wyoming
  • R. K Suarez
Document Type
Article
Publication Date
11-1-2006
Disciplines
Abstract

We sought to characterize the ability of hummingbirds to fuel their energetically expensive hovering flight using dietary sugar by a combination of respirometry and stable carbon isotope techniques. Broadtailed hummingbirds (Selasphorus platycercus) were maintained on a diet containing beet sugar with an isotopic composition characteristic of C3 plants. Hummingbirds were fasted and then offered a solution containing cane sugar with an isotopic composition characteristic of C4 plants. By monitoring the rates of CO2 production and O-2 consumption, as well as the stable carbon isotope composition of expired CO2, we were able to estimate the relative contributions of carbohydrate and fat, as well as the absolute rate at which dietary sucrose was oxidized during hovering. The combination of respirometry and carbon isotope analysis revealed that hummingbirds initially oxidized endogenous fat following a fast and then progressively oxidized proportionately more carbohydrates. The contribution from dietary sources increased with each feeding bout, and by 20 min after the first meal, dietary sugar supported similar to 74% of hovering metabolism. The ability of hummingbirds to satisfy the energetic requirements of hovering flight mainly with recently ingested sugar is unique among vertebrates. Our finding provides an example of evolutionary convergence in physiological and biochemical traits among unrelated nectar-feeding animals.

DOI
10.1086/507665
Comments

© 2006 by The University of Chicago Press. The original publication is available at http://www.jstor.org/stable/10.1086/507665

Citation Information
The original publication is available at http://www.jstor.org/stable/10.1086/507665