The Pacific reef heron (Egretta sacra), also known as the eastern reef heron or eastern reef egret, is a species of heron found throughout southern Asia and Oceania. It occurs in two colour morphs with either slaty grey or pure white plumage. The sexes are similar in appearance. Taxonomy The Pacific reef heron was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with the herons, cranes and egrets in the genus Ardea and coined the binomial name Ardea sacra. Gmelin based his description on the "Sacred heron" that had been described in 1785 by the English ornithologist John Latham in his multi-volume work A General Synopsis of Birds. The naturalist Joseph Banks had provided Latham with a specimen of a white morph that had been collected on Tahiti. The Pacific reef heron is now placed with 12 other species in the genus Egretta that was introduced in 1817 by the German naturalist Johann Reinhold Forster. The genus name comes from the Provençal French for the little egret, aigrette, a diminutive of aigron, "heron". The specific epithet sacra is from Latin sacer meaning "sacred". The Pacific reef heron is referred to by a variety of names by the indigenous peoples of the Pacific region. In New Zealand, multiple names have been given, including kākatai, matuku moana and matuku tai. It is known as belō in Fiji, matu'u in the Samoan Islands, and motuku in Niue, Tonga, and Wallis Island. Two subspecies are recognised: E. s. sacra (Gmelin, JF, 1789) – coastal south Bangladesh and Andaman Islands to Ryukyu Islands (south Japan), Australasia (except south outlying islands), Melanesia (except New Caledonia) to Tuamotu Archipelago (east Polynesia) E. s. albolineata (Gray, GR, 1859) – New Caledonia including Loyalty Islands Description Pacific reef herons are medium-sized herons, reaching 57 to 66 cm in length. They have a wingspan of between 90 and 110 cm and reach an average weight of 400 grams. The species displays an unusual, non-sexual dimorphism, with some members having entirely white plumage ('light' morph) and others (the larger portion) being charcoal-grey ('dark' morph). The reason for the colour variation or "morph", is unknown, though it is most commonly thought to be related to camouflage. The plumage of immature herons tends to be browner and duller in colour. Pacific reef herons have yellow-grey legs,