White-bellied heron

White-bellied heron

Taxonomy and systematics

This heron was first noted as the "great Indian heron" in JE Gray's Zoological Miscellany of 1844 based on Brian Houghton Hodgson from Nepal. Allan Octavian Hume noted its distinctiveness and pointed out the differences between it and Ardea sumatrana. The alternate name of Ardea imperialis was suggested by Stuart Baker, since Hodgson's name was a nomen nudum and this was used in Peters' check-list. This was used until 1963, when Biswamoy Biswas commented on Sidney Dillon Ripley's synoptic list and noted that Ardea insignis Hume should be used, since its citation as a synonym of Ardea nobilis Blyth and Ardea sumatrana Raffles was based on misidentification.

  

Description

This large heron is plain dark grey above with a long neck. The crown is dark and there are no black stripes on the neck as in the grey heron. In breeding plumage, it has a greyish-white nape plume and elongated grey breast feathers with white centers. The bill is black, greenish near the base and tip and the face is greenish grey. The bill is large and solid, with the culmen measuring 15.2–17.6 cm (6.0–6.9 in). The chin and central portion of the underside are whitish in color (per the common name), contrasting strongly against the dark grey color on the back. The legs are blackish with scale-like texture on the tarsus which measures 17.1 to 21.6 cm (6.7 to 8.5 in). In flight, it has a uniform dark grey upperwing and white underwing-coverts contrasting with dark grey flight feathers. The rump appears paler grey. At 127 cm (50 in) in height, it is the second largest heron on earth, after the Goliath heron. Included in the length, the mid-sized tail measures 19.9 to 21.6 cm (7.8 to 8.5 in). The wing chord measures 54.6 to 57.2 cm (21.5 to 22.5 in), with an estimated wingspan of 2 m (6.6 ft) or more. One estimate of body mass was relatively low at 2–2.6 kg (4.4–5.7 lb), however a deceased juvenile of the species reportedly weighed much more at 5.6 kg (12 lb). Another dead juvenile heron stood 1.58 m (5.2 ft) tall and weighed 8.51 kg (18.8 lb). These extremely high weights require verification, since they indicate this species can exceed even the typically larger Goliath heron in mass. On the ground it walks slowly, moving its neck slowly while looking from side to side. The Goliath species, beyond the average size difference, is distinguished by its chestnut neck while the slightly smaller great-billed heron is solid grey necked with the underside of the wings all grey. The usual call given when disturbed is a deep croak.

Habitat

The white-bellied heron is found in the wetlands of tropical and subtropical forests in the foothills of the eastern Himalayas of India and Myanmar. It also occurs in Bhutan's sub-tropical areas and was once found in Nepal. The major threats the heron faces are poaching (both the bird itself and its eggs) and habitat destruction (cutting of nesting trees and the disappearance of wetlands).
In Bhutan, white-bellied herons are found along the Punatsang Chu river especially in Pho-chhu river banks in Toewang Gewog, along Kami Chhu river) and in Lower Kheng (Berti). It can also be found in Madgechhu (Trongsa). A recently discovered nesting site in the Namdapha national park and Tiger Reserve in Arunachal Pradesh, India, is the first such breeding site outside of Bhutan.