Definition:

(noun) A large, fleshy sack or pouch below a bird's bill. This is part of the bird's throat, but serves several purposes. For many piscivorous birds such as pelicans, the sack is an essential part of hunting when the birds may scoop water and prey into the gular sac while diving below the surface or skimming the water, then the water is pressed out while the prey remains to be consumed.


Digestion does not take place within the gular sac, however, though if the food is lodged in the pouch and unable to be swallowed, it may begin to decompose.

Other functions of the gular sac include…

• Thermoregulation that allows the bird to better control its temperature
• Courtship displays with brilliantly colored skin or inflated pouches
• Asserting dominance, aggression or threats with displays or motion

The color and size of the gular sac can vary greatly between species as well as with how the pouch is used. When not in use, the sac may be seen as a small fold of skin, or it could disappear completely beneath the bird's plumage.

While the term gular sac generally refers only to the large pouches that are directly attached to a bird's bill, some birds have similar inflatable air sacs on the sides of their throat that serve similar functions. This is particularly prevalent in game birds such as sage-grouse and prairie-chickens. The gular sac should not be confused with wattles, however, which may also be seen below some birds' bills but are not sacs and are instead fleshy folds of skin with only limited elasticity.

Birds with prominent gular sacs include pelicans, frigatebirds, cormorants and some stork species. These pouches are also present in other animals, such as some species of frogs and lizards.

Pronunciation:

GUH-lurr SAK or GUH-larr SAK

Also Known As:

Gular Pouch, Gular Skin, Gular Fold, Throat Sac

Photo – Magnificent Frigatebird © Alan