Jeremiah Loei’s images of the Large-tailed Nightjar (Caprimulgus macrurus) show the extremely large gape, even for the chick.
According to Cleere (1999), nightjars “…have an enormous gape with an extremely sensitive palate, and are able to open their mouths both vertically and horizontally…” which come in useful in night feeding – see also HERE and HERE.
The large gape enables the bird to catch insects in flight. When opening its mouth, the lower jaw balloons from a V-shape to a semicircle, greatly increasing the catch area, thus becoming a “monster-mouth insect trap” LINK.
According to Cowles (1967), nightjars’ palate is vascular and membraneous, thus highly sensitive. This might also be an adaptation for nocturnal aerial feeding.
It has also been suggested that the large gape acts as a threat display LINK.
24th May 2018
1. Cleere, N., 1999. Family Caprimulgidae (Nightjars). In: del Hoyo, J., Elliott, A. & Sargatal, J. (eds.), Handbook of the birds of the world. Vol. 5. Barn-owls to hummingbirds. Lynx Editions, Barcelona. Pp. 302-386.
2. Cowles, G.S., 1967. The palate of the Red-necked Nightjar. With a description of a new feature. Ibis 109: 260-265.
This post is a cooperative effort between Birds, Insects N Creatures Of Asia and BESG to bring the study of birds and their behaviour through photography and videography to a wider audience.