Great Blue Heron, Gular Flutter
Gular Fluttering
The Great Blue Heron and many other birds are able to increase the airflow across the mucus membranes in their throats by opening up their bills and then vibrating their bones and upper throat muscles. Much like a dog panting, this behavior called gular fluttering, can help keep a bird cool by increasing heat loss on hot days. The great blue also exhibits a distinctive posture holding its wings out to catch the breeze and help dissipate its body head. The Great Blue Heron has a thick down coat and is completely lacking sweat glands and so so the ability to cool off is important. This video is a classic example of a Great Blue Heron keeping cool on a hot Florida day in the Celery Fields of Sarasota Florida.
The ability to maintain a high and constant body temperature enables birds to exist in a variety of areas — tropical, temperate, and polar. This achievement is not without cost, however. The “expense” of metabolic heat production must be repaid by taking in sufficient energy to balance what has been expended, and mechanisms must be available to shed excess heat when necessary. If the environmental temperature falls, birds raise their metabolic rate to prevent their internal temperature from falling as well. In contrast, if the environmental temperature becomes too hot, birds must mobilize water to lose heat through evaporative cooling (as we do when we perspire) and avoid death from overheating. .
The Great Blue Heron is an amazing fish-spearing machine. When it is gular fluttering as seen here in this video, it provides the birder with an excellent view of the tongue design and the sharp spear-like beak that this magnificent bird uses to spear fish and then align them head first down their throat.
