Pacific Reef-Heron Egretta sacra Scientific name definitions

58–66 cm; 330–700 g; wingspan 90–100 cm. Polymorphic, with white and dark grey morphs. Former has pure, all white plumage, albeit sometimes with a few dark streaks, while the latter varies in coloration, from slate-grey to brown-grey (including the underwings), with variable numbers of white feathers on chin and sometimes throat (this feature is most pronounced in Indonesian birds, but entirely absent in some populations in S & E of range); intermediate forms also occur, although considered to be rare and some records of such types might actually refer to white-morph juveniles (1 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close ). Australian dark-morph birds are generally darker than those from elsewhere, while in Rarotonga (Cook Is) (2 Rohwer, S. (1990). Foraging differences between white and dark morphs of the Pacific Reef Heron Egretta sacra. Ibis. 132(1): 21–26. Close ), Samoa (3 Tarburton, M. K. (2001). Observations on the status of the land birds, wading birds and seabirds of Samoa. Emu 101(4):349–360. Close ) and New Zealand virtually only grey birds have been reported (in latter, just one white morph in Jun 1987) (4 Crossland, A.C. (1992). First record of white phase Reef Heron (Egretta sacra) in New Zealand. Notornis. 39(4): 233–234. Close ), and, although white and dark birds co-occur over much of the species’ range (e.g. on Kai Is) (5 Johnstone, R. E., and S. (B.) van Balen (2013). The birds of the Kai and Tayandu Islands, Maluku region, Indonesia. Western Australian Naturalist 29(1):11–56. Close ), dark birds predominate at both the northern and southern extremes of its distribution, whereas the white morph seems more common in the tropics, perhaps in association with coral reefs (6 Itoh, S. (1991). Geographical variation of the plumage polymorphism in the Eastern Reef Heron (Egretta sacra). Condor. 93(2): 383–389. Close , 7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ). Intraspecific aggression resulting in death has been observed, with a dark bird killing a white bird in NE Australia (8 Beckmann, C. (2008). An intraspecific killing in adult Pacific Reef Egrets (Egretta sacra). Wilson J. Orn.. 120(2): 422–424. Close ). Male larger than female, e.g. wing length 275–292 mm versus 268–279 mm in female (1 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close ). Short stout legs (only just projecting beyond tail in flight ) and thick bill distinctive, both are all-yellow during the breeding season; short, inconspicuous crest. Non-breeding adult lacks ornamental plumes (on foreneck and back) and has duller bare parts, with bill ranging from dirty yellow to dusky or grey-brown, with blackish to greenish-horn maxilla; lores yellow-green (white morph) to grey-blue (dark morph) (1 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close ); legs very variable from yellow, greyish yellow, greenish yellow or brownish yellow, and usually darker in front and paler behind, while the feet are yellow-green with bright yellow soles. Juvenile lacks plumes and has paler bare-parts colours (lores greener, bill duller and legs more olive and less obviously bicoloured) (9 Rasmussen, P. C., and J. C. Anderton (2005). Birds of South Asia: the Ripley Guide. Lynx Edicions, Barcelona, Spain. Close ); dark morph paler and browner, sometimes with pale-scaled underparts, while white morph is similar to adult, although plumage may appear more patchily dark-flecked (9 Rasmussen, P. C., and J. C. Anderton (2005). Birds of South Asia: the Ripley Guide. Lynx Edicions, Barcelona, Spain. Close ). Race albolineata larger with longer wings, and bill can be partly black. White morph  separated from Ardea alba and A. intermedia by being smaller, yellow (not black) legs and feet, shorter plumes and more hunched posture (sometimes almost flattened to feeding substrate), while compared to E. garzetta present species is more thickset, with heavier build, shorter legs, and yellowish legs and feet, and in comparison to breeding-plumaged E. eulophotes (which see) has heavier bill, shorter legs, shorter and denser crest, shorter back plumes (not reaching tail) and yellow legs. Dark morph generally more distinctive in range, but might be briefly confused with E. novaehollandiae, except has dark head and more thickset posture, and perhaps with E. gularis in Indian Subcontinent, compared to which present species is quite differently structured, being long-bodied, with long, rather thick neck, large block-shaped head, short-legged and long-billed.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Typically coastal, especially rocky shores , coral reefs and offshore islands; also estuaries, mangroves, mudflats and sometimes sandy beaches; sometimes fields, freshwater marshes, rice fields and garbage dumps (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ). Occasionally inland , typically along rivers (10 Buden, D.W. (2000). A comparison of 1983 and 1994 bird surveys of Pohnpei, Federated States of Micronesia. Wilson Bulletin 112(3):403–410. Close ), up to 400 m above sea-level (11 Dutson, G. (2011). Birds of Melanesia: The Bismarcks, Solomons, Vanuatu and New Caledonia. Christopher Helm, London, UK. Close ), but hardly ever far from sea, although has been recorded c. 100 km from coast at L Taupo, New Zealand.

Sedentary, with some post-breeding dispersal: chick ringed at Pulau Dua (W Java) recovered 40 km away three months later; several birds ringed in Capricorn Is (off Queensland, E Australia) recovered on coast of Queensland. Some seasonal movements, e.g. large numbers reach Sentubong (Borneo) in spring, through Pattani Bay (E Malaysia) in mid Nov (1 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close ), or New Zealand with large post-breeding congregations as late as Jun. Accidental to North Korea and occasional records on coast of China and Taiwan since late 1940s, in Zheijang, Fujian, Guangdong, Hainan and Hong Kong (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ).

Mainly small crabs and fish (e.g. mudskippers, gobies, blennies and damselfishes) (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ) up to 15 cm long; less often molluscs, insects, lizards; also takes tern chicks (e.g., Black Noddies Anous minutus) (12 Buttemer, W.A. and Astheimer, L.B. (1990). Thermal and behavioural correlates of nest site location in Black Noddies. Emu. 90(2): 114–118. Close , 13 Ogden, J. (1993). On cyclones, Pisonia grandis and the mortality of Black Noddy Anous minutus on Heron Island. Emu. 93(4): 281–283. Close ), or forces adult terns to regurgitate prey. Feeds by day or night, depending on tide; active feeder , usually by Walking Slowly, but also Walking Quickly, Running or Hopping, and using techniques  such as Wing Flicking, Spread Wing, Gleaning, Foot Stirring, Foot Paddling, Foot Dragging, Hovering and Diving to secure prey, which is sometimes struck at over distances of up to 2 m (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ). Usually feeds alone or in pairs , occasionally in family groups or larger groups if food is particularly abundant (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ); however, usually highly territorial, each bird defending feeding territory. Some differences apparent between morphs, particularly in habitat choice and foraging behaviour, e.g. white morphs tend to feed in surf, whereas dark birds choose to run and walk along reef flats in search of prey, and on Mangaia, in S Cook Is, white-morph birds tended to use windward side of island and dark-morph birds the lee side (2 Rohwer, S. (1990). Foraging differences between white and dark morphs of the Pacific Reef Heron Egretta sacra. Ibis. 132(1): 21–26. Close , 7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ).

Vocalizations not well described and frequently silent, but gives an “ork” or deep “gruk” while feeding (similar to Northern Raven Corvus corax), a “crraw” in alarm or nasal “gyaaah, gyaaah” in flight, a downslurred, mellow, staccato “nyarp” or a harsher, flatter and more purring “nyaah” (9 Rasmussen, P. C., and J. C. Anderton (2005). Birds of South Asia: the Ripley Guide. Lynx Edicions, Barcelona, Spain. Close ), various harsh croaking sounds in greeting between pair members, and bill-snaps during breeding season (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close , 14 Brazil, M. (2009). Field Guide to the Birds of East Asia: Eastern China, Taiwan, Korea, Japan and Eastern Russia. Christopher Helm, London, UK. Close ).

In India, May–Jul, Sept; in Malaysia May, Jun and Nov; in W Java, Sept–Apr; in New Zealand, Sept–Dec, in New Caledonia, Jan–Feb (15 Barré, N., Tron, F., Chartendrault, V., Okahisa, Y., Sato, N.J., Legault, A. and Theuerkauf, J. (2013). Breeding seasons of landbirds in New Caledonia. Wilson J. Orn.. 125(2): 384–398. Close ); in Australia (and many Pacific islands) (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ), year-round, peaking Sept–Jan. Nests singly or in small colonies, up to 20–70 pairs, or 200–300 birds in N Australia; sometimes in mixed colonies with other species; nests on ground, cliff ledges, bushes or small trees (e.g. Cocos and Pandanus) (16 Buden, D. W. (1998). The birds of Kapingamarangi Atoll including the first record of the Shining Cuckoo (Chrysococcyx lucidus) from Micronesia. Notornis 45(3):141–153. Close ), up to 3 m high, and sometimes in close proximity to humans, e.g. below a pier (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ). Nest constructed of sticks, lined with leaves and grass, and typically c. 40 cm in diameter and just few cm high (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ). Normally 2–3 pale greenish-blue eggs  (2–6), in Japan 3–5 and in Australia 4–5, size 40–44·8 mm × 32·5–35 mm (1 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close , 7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ); incubation 25–28 days by both adults (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ); chicks  have dark grey down, pinkish bill with black tip to maxilla, and grayish-pink legs (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ); fledging c. 50 days, but young leave nest at c. 3 weeks (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ). No further information.

Not globally threatened (Least Concern). Relatively common, abundant in many islands of SW Pacific, with no evidence for recent changes in abundance, e.g., on Tahiti (French Polynesia) (17 Monnet, C., J.-C. Thibault, and A. Varney (1993). Stability and changes during the twentieth century in the breeding land-birds of Tahiti (Polynesia). Bird Conservation International 3(4):261–280. Close ) or Pohnpei (Micronesia) (10 Buden, D.W. (2000). A comparison of 1983 and 1994 bird surveys of Pohnpei, Federated States of Micronesia. Wilson Bulletin 112(3):403–410. Close ). In Japan, common along coasts with warm currents; still fairly common in Thailand; locally common to very common around Sumatra. In Australia, common along N coast and Great Barrier Reef, becoming steadily less frequent towards S, and has declined in S Australia and on Tasmania (7 Kushlan, J. A., and J. A. Hancock (2005). The Herons. Oxford University Press, Oxford, UK. Close ). In New Zealand, more frequent in N, declined during second half of 20th century due to transformation of habitat and was formerly regarded as Vulnerable nationally; more recently, population has been stable and was recently estimated at 400–500, with a recommendation that it no longer be considered threatened there (18 Bell, M. (2010). A census of reef herons (Ardea sacra) in the Marlborough Sounds. Notornis. 57(3): 152–155. Close ). Presence and status in Bangladesh unclear (only one record, in Jan 2010, appears to be documented), although probably only a vagrant (19 Thompson, P. M., W. G. Harvey, D. L. Johnson, D. J. Millin, S. M. A. Rashid, D. A. Scott, C. Stanfield, and J. D. Woolner (1993). Recent notable bird records from Bangladesh. Forktail 9: 13–44. Close , 20 Thompson, P. M., S. U. Chowdhury, E. Ul Haque, M. M. H. Khan, and R. Halder (2014). Notable bird records from Bangladesh from July 2002 to July 2013. Forktail 30:50–65. Close ); however, in addition to this species, E. gularis might also occur there (9 Rasmussen, P. C., and J. C. Anderton (2005). Birds of South Asia: the Ripley Guide. Lynx Edicions, Barcelona, Spain. Close , 20 Thompson, P. M., S. U. Chowdhury, E. Ul Haque, M. M. H. Khan, and R. Halder (2014). Notable bird records from Bangladesh from July 2002 to July 2013. Forktail 30:50–65. Close ).