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.


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


birds, nestlings, bank swallows, Riparia riparia, burrows

Subject Categories

Bank swallows


Poultry or Avian Science


University of Chicago

Publication Date


Rights Information

Copyright 1981

Rights Holder

University of Chicago

Click button above to open, or right-click to save.