Chris Lee’s a.k.a. chrisle023 image of a Milky Stork (Mycteria cinerea) was photographed in November 2009 at Singapore’s Sungei Buloh Wetland Reserve. The status of these storks are debateable – either vagrant or escapee, as they were introduced by the Mandai Zoo as free-flying birds since 1987, now breeding freely there.
The Milky Stork is here taking a classic delta-wing posture. Note that the dull pinkish legs and feet are almost white, coated with the bird’s droppings. This is done intentionally in order to lose heat through evaporation of the faecal fluids. Technically known as urohidrosis, this is commonly seen in storks (Ciconiidae) and New World vultures (Cathartidae).
Sunning is usually done in early morning or late afternoon. The wings may be spread fully in an open-wing frontal posture or as shown here, in a delta-wing posture. Such postures may also be adopted for wing-drying, in which case the bird faces the wind whether the sun is out or not. For cooling purposes the bird faces away from the sun with the upper back feathers erected. At the same time the bird will be panting.
This post is a cooperative effort between NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.
Simmons, K. E. L., 1986. The sunning behaviour of birds: A guide for ornithologists. Bristol Ornithological Club, Bristol. 119pp.