Body surface rewarming in fully and partially hypothermic king penguins

Area of Science:

• Physiology
• Animal Ecology
• Thermoregulation

Background:

• Penguins experience significant thermal challenges transitioning from cold sea to warmer land after foraging.
• Uninsulated appendages like flippers and feet are potential sites for heat exchange during rewarming.
• Peripheral vasodilation plays a crucial role in regulating body temperature during recovery.

Purpose of the Study:

• To test the hypothesis that peripheral vasodilation is delayed during the rewarming of hypothermic penguins.
• To investigate the influence of internal body temperature on the rate of surface rewarming in king penguins.
• To compare rewarming patterns in laboratory and field conditions.

Main Methods:

• Examined surface rewarming patterns in fully and partially hypothermic king penguins (Aptenodytes patagonicus) in a laboratory setting.
• Measured cloacal and peripheral (flippers, feet, breast) temperatures during a 21-minute rewarming period.
• Recorded surface temperatures of free-ranging penguins upon returning to their colony.

Main Results:

• Both fully and partially hypothermic penguins rewarmed, with greater temperature changes observed in fully hypothermic individuals.
• A 5-minute delay in peripheral temperature increase was noted in fully hypothermic birds compared to partially hypothermic ones.
• Free-ranging penguins exhibited lower initial surface temperatures and less change over time compared to laboratory subjects.

Conclusions:

• Penguin appendage vasodilation is flexibly regulated during rewarming after foraging.
• Rewarming recovery is influenced by the degree of hypothermia (internal temperature) and ambient environmental conditions.
• Laboratory findings provide insights into physiological responses, while field data highlight the impact of natural conditions on penguin thermoregulation.