Deep dives and aortic temperatures of emperor penguins: new directions for bio-logging at the isolated dive hole

In order to document deep (> 100 m) dives and aortic temperature responses of emperor penguins (Aptenodytes forsteri) at an isolated dive hole, and also to evaluate a new catheterization technique, three birds were equipped with time depth recorders, temperature data loggers, and percutaneously-inserted aortic thermistors. After recovery from anesthesia, they were provided access for one day to the dive hole. The birds tolerated the experiment without complication. Mean diving duration (± SE) of 83 dives was 5.9 ± 3.1 min; 55% of dives were > 5.6 min, the previously determined aerobic dive limit; 36% were > 100 m in depth. Mean aortic temperatures during 3-h rest periods ranged from 37.3 ± 0.2°C to 38.0 ± 0.1°C. Mean dive temperature did not correlate with dive duration, and the grand mean of mean dive temperatures in each bird ranged from 38.3 ± 0.2°C to 39.0 ± 0.2°C; there was no evidence of core hypothermia during dives. Reliable, safe catheterizations, and the large percentage of deep/long dives of these birds should provide the basis both for future studies of pressure adaptation and hypoxemic tolerance in diving emperor penguins, and for investigation of deep-dive foraging behavior. key words: aorta, dive, emperor penguin, temperature