Diving heart rates in Adélie penguins (Pygoscelis adeliae)

Abstract l. In Antarctica, two Adélie penguins were implanted with heart rate (HR) transmitters and released in their breeding colony where they resumed incubation. 2. HR while at rest and lying in the colony were 67 and 77 beats per min (bpm), respectively. 3. For diving experiments, the birds were introduced into a still-water canal, 21 m long, with one respiration chamber at each end. 4. The birds swam underwater for 49 and 76% of the time at speeds of 1.5 and 2.5 m/sec, respectively. 5. When floating quietly at the surface, HR in the first penguin was 89 bpm. 6. Pre-dive HR varied with duration of the inter-dive interval, being highest (250 bpm) when the bird dived in rapid succession (surface times < 5 see) and close to diving HR when surface time was 50 sec. 7. Mean HR while diving was constant (107 bpm) and did not vary either with surface time, or with time submerged (0–15 sec). 8. Pre-dive HR and diving HR were not correlated, 9. The extent of bradycardia upon immersion was dependent upon surface time. 10. There was a good correlation between HR and oxygen consumption in both birds, suggesting that HR might be used to determine energy expenditure