Respiratory gas concentrations and temperatures within nest cavities of the northern flicker (Colaptes auratus)

Abstract

Listen

Translate article

We measured respiratory gas concentrations and air temperatures within nest cavities occupied by the northern flicker. (Colaptes auratus). The means of all measurements of carbon dioxide and oxygen concentrations were 0.37 and 20.42%, respectively. The maximal carbon dioxide level recorded was 2.56%, while the minimal oxygen level was 18.04%. There was a diel cycle in the levels of respiratory gases in nest cavities, with peak carbon dioxide and minimal oxygen levels occurring between 22:00 and 24:00. However, the gaseous conditions within nest cavities remained essentially unchanged throughout the nestling period. Cavity air temperature averaged 21.2 °C, ranging from 10.2 to 33.8 °C, and nearly always exceeded the outside air temperature. The mean difference between inside and outside air temperatures was 7.1 °C and is comparable with those reported in other studies of cavity microenvironments. The elevated cavity temperatures may reduce energy requirements of developing young and also may induce a convective transfer of air between the cavity and free atmosphere that would moderate gaseous conditions within the cavity.