20-12-2023 KARTONG, GAMBIA - WESTERN REEF HERON (Egretta gularis)

The western reef heron (Egretta gularis), also called the western reef egret, is a medium-sized heron found in southern Europe, Africa and parts of Asia. It has a mainly coastal distribution and occurs in several plumage forms: a slaty-grey plumage in which it can only be confused with the rather uncommon dark morph of the Little egret (Egretta garzetta); a white form which can look very similar to the little egret although the bill tends to be paler and larger and the black form with white throat E. g. gularis of West Africa. There are also differences in size, structure and foraging behaviour. There have been suggestions that the species hybridizes with the Little Egret, and based on this, some authors treat schistacea and gularis as subspecies of Egretta garzetta. Works that consider the Western Reef Heron as a valid species include the nominate gularis and schistacea as subspecies.

This bird has two plumage colour forms. There is an all-white morph and a dark grey morph; morphs can also occur with intermediate shades of grey which may be related to age or particoloured in grey and white. The white morph is similar in general appearance to the little egret, but has a larger yellower bill, extended yellow on thicker legs, and when foraging tends to be very active, sometimes also moving its wing or using it to shade the water surface. The grey morph has a whitish throat and is unlikely to be confused with any other species within the range of this egret with beak and legs similar to that of the white morph. During the breeding season the legs and facial skin are reddish. Breeding birds have two long feathers on the sides of the nape. The nominate subspecies gularis has a range from West Africa to Gabon, with some birds breeding in southern Europe. Subspecies schistacea (Hemprich & Ehrenberg, 1828) breeds from the Persian Gulf along the coast of India to the east of the India Peninsula. The bill of gularis is more pointed while schistacea has the larger bill especially towards the base. The form on the eastern coast of South Africa is usually separated as the dimorphic egret Egretta dimorpha. The dark and white morph is thought to be controlled by a single allele with the dark character being incompletely dominant over the gene for white.

These birds stalk their prey in shallow water, often running or stirring the water with their feet or flicking their wings to disturb prey; they may also stand still and wait to ambush prey. They eat fish, crustaceans, and molluscs. In coastal areas, they regularly feed on mudskippers. Laboratory studies show them to be capable of making corrections for refractions but the probability of missing increases when they are forced to strike at prey at very acute angles to the water surface. Like other herons and egrets they have few vocalizations, making a low kwok or grating sounds when disturbed or near the nest.

The western reef heron's breeding habitat is coastal wetlands. In the Red Sea region the breeding season is from June to August. The nominate subspecies breeds in West Africa from late April to September. In India the breeding season is during the monsoon rains from April to August and end of May in the former breeding colony at Chilaw in Sri Lanka. Most of the breeding colonies in Gujarat in western India were on mangroves. They nest in colonies usually of their own species but sometimes with other egrets and smaller herons, usually on platforms of sticks placed in trees or shrubs. The male fetches sticks of the nest while the female places them to form the platform. The nest height varies from about 5 to 15 meters, but very low nesting (as low as 0.6 meters) has been observed in mangrove trees in salt pans. The usual clutch is three to four eggs which are light blue as in the little egret. Incubation begins when the first egg is laid resulting in chicks with size disparities. Both parents take turns to incubate and the eggs hatch after about 23 to 24 days. The chicks are white with grey dapples. Young birds sometimes die after falling off from the nest platform. Adults will shade the chicks during the hotter parts of the day. Predators of eggs include rats and young chicks may be taken by cats and crows. Adults usually guard the nest when eggs or young chicks are present. Adults feed the young by regurgitating semi-digested food at the nest. This diet includes mainly small fishes of the families Clupeidae, Gobiidae and Engraulidae. The young birds leave the nest after about a month.