Black-Headed Ibis

The black-headed ibis is also known as the black-necked ibis, Indian white ibis and Oriental white ibis. It is found in South and Southeast Asia, from India to Japan, but is most widespread and breeding in India, Sri Lanka, Nepal and Myanmar. It has white plumage and a black head, neck, bill, legs and feet. The tail has light gray ornamental feathers. The head and neck are naked. We saw only a few black-headed ibis: from a long distance in Minneriya National Park and in a small lake in Yala National Park.

In Yala NP. 

In breeding season bare patches under the wings turn red, the head may get a bluish tinge, or a pink or bright red patch behind the neck, the tail may turn jet black and it may get a yellowish coloration on the breast and back. 

We were apparently there during breeding season as this ibis has a blue tinge on the neck and some yellow under the tail. 

The ibis on the left at Lake Minneriya NP, has the red under the wings and yellow tail and back.