Multi-author Review Ecological Implications of Metabolic Biochemistry


, Volume 48, Issue 6, pp 565-570

First online:

Hummingbird flight: Sustaining the highest mass-specific metabolic rates among vertebrates

  • R. K. SuarezAffiliated withDepartment of Biological Sciences, Simon Fraser University

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Resting and maximal mass-specific metabolic rates scale inversely with body mass. Small hummingbirds achieve the highest known mass-specific metabolic rates among vertebrate homeotherms. Maximal capacities for O2 and substrate delivery to muscle mitochondria, as well as mitochondrial oxidative capacities in these animals may be at the upper limits of what are structurally and functionally possible given the constraints inherent in vertebrate design. Such constraints on the evolutionary design of functional capacities may play an important role in determining the lower limits to vertebrate homeotherm size and the upper limits to mass-specific metabolic rate.

Key words

Oxygen consumption exercise evolutionary design muscle mitochondria energy metabolism enzymes