"Gular fluttering" When its hot outside birds will occasionally open their mouths and begin to flutter & vibrate their neck muscles the reason for this is to thermoregulate (Cool down) its the same reason you'll see dogs panting. Birds dont have sweat glands so instead they have to Gular flutter. This is exactly what this Cormorant is doing. When birds Gular flutter, they rapidly pump air back and forth in their system, thereby causing a very efficient form of evaporative cooling. Ive only ever witnessed this happen with Herons & Cormorants but many other birds do it too! Some very interesting bird behaviour to have observed! #1dxmarkii #thisislondon #bushypark #500mm #nature #wildlife #liveforthestory #naturephotography #cormorant #nature_perfection #wildlifeplanet #wildlifephotography #birdbehaviour #birdphotography #britishwildlife#earthcapture #shots_of_animals #marvelouz_animals #nb_nature_brilliance #splendid_animals #birds_perfection #featured_wildlife #earthpix #rspb_love_nature #wildgeography #nuts_about_wildlife #conkernaturepotd