“On a hot and sunny afternoon, I decided to hunt for the Savanna Nightjar (Caprimulgus affinis) at a known location in Tuas. Having approached it carefully at a close distance without flushing it away, I managed to capture a video of the encounter. What struck me immediately was that it was rapidly fluttering it’s throat area with it’s mouth opened. My guess was that it was trying to cool itself down in the hot environment.
“Upon return, I managed to find out that what is was doing is called gular fluttering. An excerpt: “An important environmental adaptation for many caprimulgiformes is the ability to withstand high ambient temperature (Ta). Birds of this order are most common in warm climates, and frogmouths, potoos, and nightjars all roost and nest in the open where they can be subjected to long periods of direct sun exposure. In these circumstances, they avoid hyperthermia by using evaporative cooling strategies. Nightjars dissipate heat by gular fluttering, during which the mouth is opened, the rate of blood flow to the buccal area is increased, and the moist gular area is rapidly vibrated.” (Fowler and Miller 2003: 225) LINK.
23rd August 2011