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Goliath heron

Ardea goliath


Description

This is the world's largest heron. The height is 120–152 cm (47–60 in), the wingspan is 185–230 cm (73–90.5 in) and the weight is 4–5 kg (8.8–11.0 lb). Among standard measurements, the tarsus measures from 21.2 to 25.5 cm (8.3 to 10.0 in) and the wing chord averages around 60.7 cm (23.9 in) in length. The culmen measures from 18 to 20 cm (7.1 to 7.9 in), while the bill from the gape measures around 24 cm (9.4 in). In flight it has a slow and rather ponderous look and, unlike some other herons, its legs are not held horizontally.

Male and female look similar, with an overall covering of slate gray and chestnut feathers. The head and its bushy crest, face, back and sides of the neck are chestnut. The chin, throat, foreneck and upper breast are white, with black streaks across the foreneck and upper breast. The lower breast and belly are buff with black streaks. The back and upper wings are slate-grey, with a chestnut shoulder patch at the bend of the wings when they're closed. The under-wing is pale chestnut. The upper mandible is black and the lores and orbital areas are yellow with a greenish tinge. The eyes are yellow while legs and feet are black. Juveniles look similar to the adults, but are paler.

The only heron with somewhat similarly-colorful plumage characteristics, the widespread purple heron, is much smaller than the Goliath. Despite the shared plumage characteristics with the purple species, the closest extant relatives of the Goliath are considered to be the great-billed and the white-bellied herons of Southern Asia. Due to their large size, this species trio is sometimes referred to as the "giant herons".

The Goliath heron has a distinct deep bark, often described as kowoork, audible from a distances of up to 2 km. A disturbance call (arrk), sharper and higher, can also occasionally be heard. A huh-huh is given during the crouched stage, while a krooo may be heard with the neck extended. Organ-like duetting has been reported at nest sites but has not been confirmed.


Fun Facts

Goliath herons are solitary foragers and are highly territorial towards other Goliaths entering their feeding territories. On occasions, two may be seen together but these are most likely to a be breeding pair or immatures. A diurnal and often rather inactive feeder, this heron often hunts by standing in the shallows, intently watching the water at its feet. This is a typical feeding method among large Ardea herons and it can forage in deeper waters than most due to its larger size.

It may also perch on heavy floating vegetation, in order to prevent water from rippling around them. As prey appears, the heron rapidly spears it with open mandibles, often spearing both mandibles through the fish's body, and then swallows it whole. It is possible that the bill is used in a lure-like fashion occasionally, attracting fish to the immobile, large object submerged in the water. The handling period is long, with herons often placing their struggling prey on floating vegetation while preparing to swallow it. Due to its generally slow movements and handling time, the Goliath is frequently vulnerable to kleptoparasitism.

In Africa, African fish eagles frequently pirate food caught by Goliaths, although other large birds such as saddle-billed storks and pelicans may also steal their prey. Prey almost entirely consists of fish. The Goliath heron specializes in relatively large fish, with an average prey weight range in Natal of 500–600 g (1.1–1.3 lb) and length of 30 cm (12 in). Exceptionally, the largest fish targeted may measure 50 cm (20 in) although the heron may not be able to swallow prey up to this size. Small fish are generally ignored and the average Goliath catches around 2 or 3 fish a day. Breams, mullet, tilapia and carp have locally been recorded as preferred species. Any other small animals that they come across may be eaten, including frogs, prawns, small mammals, lizards, snakes, insects and even carrion.


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