Ardea alba, commonly known as Great White Egret or Great Egret was first described by Linnaeus in the year 1758. Previously, it was classified under the genus Casmerodius as C. albus (Sibley & Monroe 1990, 1993), but recently Hoyo and Collar (2014) revised its genus and placed it under the genus Ardea. The four subspecies of Ardea alba are classified according to a different region where populations in the southern Palearctic (from central Europe to Russian Far East) known as A. alba, while A. modesta population are distributed in India to northeastern China and Japan to Australia. In addition, the subspecies A. melanoryncha is recorded in Africa, and Madagascar and A. egretta found in North and South America.
Compared to other egret groups, this species has a much larger body size. The wingspan of this bird can reach up to 145 cm, and the body length ranges from 94 cm to 104 cm. It has a long S-shaped neck, long leg, white body and a dagger-like bill. The non-breeding adult has a yellow bill with blackish legs, while the breeding adult has a blackish bill and a reddish leg. The juvenile has a similar morphology as the non-breeding adult. In flight, its neck is tucked in, and the legs extend far from its tail.
The species can be found in both freshwater and saltwater habitats such as coastal and inland water bodies, paddy fields and mangroves (del Hoyo et al.,1992). It is a diurnal feeder and commonly active during dawn and dusk in coastal areas where its feeding behavior is influenced by the tide cycle (Kushlan & Hancock, 2005). During hunting, the bird stands still observing its prey, and as its target passes by, it will strike with its bill at an incredible speed. The diets for this species include fishes, frogs, crustaceans, and other small aquatic animals. In drier habitats, lizards, small birds and mammals are some of the choices of its food (del Hoyo et al., 1992).
An average life span of Ardea alba in the wild can be up to 15 years. The populations in the tropics are usually bred in a place (del Hoyo et al., 1992) and sometimes will migrate to another habitat when the rainfall season starts (Brown et al., 1982). Ardea alba usually moves locally in response to breeding or wintering needs. Thus, it is resident or partially migrant species when one fraction of the population is migratory while the others are sedentary (Corrêa et al., 2016). Commonly, the Great Egret starts making its nest when the raining season peaks as the food resources are abundantly available (Kushlan & Hancock, 2005). Great Egret in Palearctic and Nearctic ecozone will begin to migrate when comes its breeding season (Flint et al.,1984; del Hoyo et al., 1992). Kushlan and Hancock (2005) reported that the populations in the temperate region breed in the summer and winter seasons. Once the breeding season over, the bird will migrate to a new breeding site (del Hoyo et al., 1992).
The conservation status for Ardea alba in the IUCN Red List of Threatened Species as Least Concern (LC) due to its extensive distribution range. Besides, the population size is large. Thus, it does not approach the threshold for Vulnerable. However, in the past, Great Egret were highly threatened by hunting for their white feather and used in plume trade. Nowadays, the species suffered from loss and degraded of wetland habitats due to invasions, land reclamations and pollution. Ardea alba is totally protected under the Wildlife Conservation Act 2010 (Act 716) in the second scheduled where hunting is not permitted.
