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Development Of Endothermy In Nestling Bank Swallows (Riparia Riparia), Richard L. Marsh

Richard Marsh

Body temperature (Tb) measurements after exposure to air temperatures (Tₐ) of 20 C or 27 C for 2 h in conjunction with metabolism measurements were used to describe the timing of and basis for developing temperature regulation in nestling swallows. As growth proceeds from hatching to 10 g there is a gradual increase in the Tb after exposure to low Tₐ. As growth continues beyond this point, the ability of nestlings to maintain Tb above Tₐ improves rapidly, such that nestlings weighing over 14 g are completely homeothermic when exposed to 20 C. Conductance (C, in cal [g⋅h⋅°C]⁻¹) decreases throughout …