Effects on nestling age and burrow depth on CO₂ and O₂ concentrations in the burrows of bank swallows (Riparia riparia)

Steven J. Wickler, University of Michigan - Ann Arbor
Richard L. Marsh, University of Michigan - Ann Arbor

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Originally published in Physiological Zoology, 54:132–136, January 1981. http://www.journals.uchicago.edu/doi/abs/10.1086/636920

Abstract

Gas samples were taken from the nest chambers of bank swallows (Riparia riparia) and analyzed for CO₂ and O₂ content. The mean CO₂ content was 2.62% with a maximum value of 5.58%, and the mean O₂ content was 17.83% with a minimum value of 14.61%. There was a positive and significant correlation of increasing CO₂ content with both increasing nestling age and increasing total metabolizing mass (adults plus young). With increasing metabolizing mass there is a linear increase in CO₂ content, which suggests no active regulation of gas concentrations. Burrow depth also affected CO₂, particularly in burrows with older nestlings. The effect of depth is most likely due to the relative importance of convective exchange rather than to diffusion. The increase in CO₂ was proportional to the decrease in O₂ with a ratio of CO₂:O₂ equal to 0.86.