The images by Lim Poh Bee show the Oriental Pied Hornbill (Anthracoceros albirostris) sunbathing on a frond of a coconut palm, with wings fully stretched. In the other image, it has one of its wings raised to expose the underside to the sun and breeze.
Hornbills regularly sunbath, bathe in the rain or dry their feather after getting them wet. When sunbathing, they have their back facing the sun, the head feathers raised and the preen gland exposed.
The Buceros hornbills in particular often indulge in bizarre postured to sunbathe. Ground hornbills often lie on the ground with their wings spread.