The Purple Heron (Ardea purpurea) is a common resident in Singapore. Formerly more widespread, the population decline has been attributed to loss of nesting grounds and human disturbances.
KN Pan’s study of the heron in comfort behaviour shows it exposing the inner wing feathers to the sun for about five minutes before preening the feathers (above). Preening takes up a substantial amount of time as the bird needs to keep the feathers in top form. This is done with the aid of the massive bill.
Where the bill cannot reach, like around the head, the extremely long middle toe comes into play. Note that the leg is raised from under the wing to reach the head, characteristic of terrestrial birds (left). Among aboreal birds, the leg is extended over the wing to reach the head, as seen in Barn Swallow (Hirundo rustica).
According to our bird specialist R Subaraj, the Purple Heron above is not a full adult. Based on the colour of the wings and back, it is slowly becoming one.
Wang, L.K. & C. J. Hails, 2007. An annotated checklist of birds of Singapore. Raffles Bulletin of Zoology, Supplement 15: 1-179.
This post is a cooperative effort between NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.