BirdNote Daily The Heart of a Bird
Jan 24, 2026
A lively look at how bird physiology powers flight. Short takes on dinosaur ancestry and warm-bloodedness. Notes on high body temperatures and oversized four-chambered hearts. Fascinating comparisons of heart rates, from hummingbirds to pigeons versus humans.
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Birds' High Metabolism And Ancestry
- Birds maintain a high constant body temperature (around 106°F) via endothermy inherited from theropod ancestors.
- Their relatively large four-chambered hearts and efficient circulation support greater oxygen delivery needed for flight.
Cardiovascular Power Fuels Flight
- Birds' hearts are larger relative to body size and pump more oxygen-rich blood per minute than mammals' hearts.
- These cardiovascular adaptations meet the extreme energy demands of sustained flight and rapid heat loss in small bodies.
Avian Heart Rates Outpace Humans
- Small birds can reach extraordinary heart rates: hummingbirds ~1,200 bpm and pigeons ~600 bpm while flying.
- Even an exercising human reaches only about 150 bpm, far below typical avian rates.