Wild white-capped noddies keep a cool head in a heated situation

Area of Science:

• Avian biology
• Thermoregulation
• Behavioral ecology

Background:

• Sunning behavior is widespread in birds, but can lead to heat stress and impaired brain function.
• Birds may possess mechanisms to selectively cool their brains during sunning.
• Potential cooling mechanisms include physiological adaptations or passive traits like plumage coloration.

Purpose of the Study:

• To investigate thermoregulatory strategies in white-capped noddies during sunning.
• To determine if plumage coloration plays a role in brain cooling in these seabirds.

Main Methods:

• Infrared thermography was used to measure surface temperatures of wild white-capped noddies while sunning.
• Thermal profiles of the white cap and black back were compared.
• Thermal imaging was also performed on a deceased bird to assess the role of coloration versus physiology.

Main Results:

• The white cap of sunning white-capped noddies was 20°C cooler than the black back.
• This thermal difference persisted in a deceased bird, indicating it's due to dichromatic coloration.
• The findings suggest plumage, not physiology, drives the cap's lower temperature.

Conclusions:

• The white cap coloration likely facilitates brain cooling during sunning in white-capped noddies.
• This adaptation may allow for extended sunning periods, potentially aiding in parasite control.
• Passive thermoregulation via plumage coloration is a significant factor in avian behavior.