Pacific reef heron

{{Short description|Species of bird}} {{Use British English|date=May 2014}} {{Use dmy dates|date=January 2020}} {{Speciesbox | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=BirdLife International |year=2018 |title=''Egretta sacra'' |article-number=e.T22696980A131759460 |doi=10.2305/IUCN.UK.2018-2.RLTS.T22696980A131759460.en}}</ref> | image = Egretta sacra.jpg | image_caption = Dark morph | image2 = Eastern Reef Egret.jpg | image2_caption = Light morph | genus = Egretta | species = sacra | authority = (Gmelin, 1789) | range_map = Egretta sacra map.svg }}

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''.<ref>{{ cite book | last=Gmelin | first=Johann Friedrich | author-link=Johann Friedrich Gmelin| year=1789 | title=Systema naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis | edition=13th | volume=1, Part 2 | language=Latin | location=Lipsiae [Leipzig] | publisher=Georg. Emanuel. Beer | pages=640–641 | url=https://www.biodiversitylibrary.org/page/2656133 }}</ref> 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.<ref>{{ cite book | last=Latham | first=John | author-link=John Latham (ornithologist) | year=1785 | title=A General Synopsis of Birds | volume=3, Part 1 | publisher=Printed for Leigh and Sotheby | location=London | pages=92–93, No. 62 | url=https://www.biodiversitylibrary.org/page/40078851 }}</ref><ref>{{ cite book | editor1-last=Mayr | editor1-first=Ernst | editor1-link=Ernst Mayr | editor2-last=Cottrell | editor2-first=G. William | year=1979 | title=Check-List of Birds of the World | volume=1 | edition=2nd | publisher=Museum of Comparative Zoology | location=Cambridge, Massachusetts | page=215 | url=https://www.biodiversitylibrary.org/page/16108855 }}</ref> 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.<ref>{{ cite book | last=Forster | first=T. | author-link=Thomas Ignatius Maria Forster | year=1817 | title=A Synoptical Catalogue of British Birds; intended to identify the species mentioned by different names in several catalogues already extant. Forming a book of reference to Observations on British ornithology | publisher=Nichols, son, and Bentley | location=London | page=59 | url=https://www.biodiversitylibrary.org/page/13330976}}</ref><ref name=ioc>{{cite web| editor1-last=Gill | editor1-first=Frank | editor1-link=Frank Gill (ornithologist) | editor2-last=Donsker | editor2-first=David | editor3-last=Rasmussen | editor3-first=Pamela | editor3-link=Pamela Rasmussen | date=August 2022 | title=Ibis, spoonbills, herons, Hamerkop, Shoebill, pelicans | work=IOC World Bird List Version 12.2 | url=https://www.worldbirdnames.org/bow/pelicans/ | publisher=International Ornithologists' Union | access-date=28 November 2022 }}</ref> 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".<ref>{{cite book | last=Jobling | first=James A. | year=2010| title=The Helm Dictionary of Scientific Bird Names | publisher=Christopher Helm | location=London | isbn=978-1-4081-2501-4 | pages=[https://archive.org/stream/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling#page/n143/mode/1up 143], [https://archive.org/stream/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling#page/n345/mode/1up 345]}}</ref> 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''.<ref>{{cite book |last=Ryan |first=P. M. |date=2012 |title=The Raupo Dictionary of Modern Māori |publisher=Raupō |isbn=978-0-14-356789-9 }}</ref> It is known as ''belō'' in Fiji, ''matu'u'' in the Samoan Islands, and ''motuku'' in Niue, Tonga, and Wallis Island.<ref name="Watling">{{cite book |last=Watling |first=Dick |date=2001 |title=A guide to the birds of Fiji & Western Polynesia |publisher=Environmental Consultants Fiji |location=Suva, Fiji |page=99}}</ref>

Two subspecies are recognised:<ref name=ioc/> * ''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 {{cvt|57|to|66|cm}} in length. They have a wingspan of between {{cvt|90|and|110|cm}} and reach an average weight of {{cvt|400|g}}. 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.<ref name="Edgar">{{cite journal |last1=Edgar |first1=A. T. |date=1978 |title=The reef heron (''Egretta sacra'') in New Zealand |url=https://www.birdsnz.org.nz/wp-content/uploads/2021/12/Notornis_25_1.pdf |journal=Notornis |volume=25 |issue=1 |pages=25–58 }}</ref>

Pacific reef herons have yellow-grey legs, and the grey variety's throats and chins are marked by a narrow, white stripe. They have brown beaks, gold-yellow coloured eyes and the surrounding areas of their faces are normally of a greenish to yellow cast.<ref name="Edgar" /><ref name=hanzab>{{cite book | editor1-last=Marchant | editor1-first=S. | editor2-last=Higgins | editor2-first=P.G. | year=1990 | chapter=''Ardea sacra'' Eastern Reef Egret | title=Handbook of Australian, New Zealand & Antarctic Birds. Volume 1: Ratites to ducks; Part B, Australian pelican to ducks | location=Melbourne, Victoria | publisher=Oxford University Press | isbn=978-0-19-553068-1 | pages=1002–1009, Plate 71 | chapter-url=https://nzbirdsonline.org.nz/sites/all/files/151_Reef%20Heron.pdf | archive-date=27 July 2024 | access-date=29 November 2022 | archive-url=https://web.archive.org/web/20240727034851/https://nzbirdsonline.org.nz/sites/all/files/151_Reef%20Heron.pdf }}</ref>

== Distribution and habitat == The Pacific reef heron is widely distributed across southern Asia and Oceania. In Australia, Pacific reef herons inhabits most of the coastline, and offshore islands including the Torres Strait Islands.<ref>{{cite journal |last1=Lavery |first1=Tyrone H. |last2=Watson |first2=Justin J. |last3=Leung |first3=Luke K.-P. |date=2012 |title=Terrestrial vertebrate richness of the inhabited Torres Strait Islands, Australia |journal=Australian Journal of Zoology |volume=60 |issue=3 |pages=180–191 |doi=10.1071/ZO12043 |s2cid=73537024 }}</ref>

Pacific reef herons are widespread across Micronesia, with breeding records in Guam, the Marshall Islands, Northern Mariana Islands, and Palau, among various other islands.<ref>{{cite journal |last1=Wiles |first1=Gary J.|date=2005 |title=A checklist of the birds and mammals of Micronesia |journal=Micronesia |volume=38 |issue=1 |pages=149–189}}</ref> The species also breeds throughout western Polynesia, including in Fiji,<ref name="Watling" /> French Polynesia,<ref>{{cite journal |last1=Beaune |first1=David |last2=Ghestemme |first2=Thomas |last3=Raust |first3=Philippe |last4=Blanvillain |first4=Caroline |date=2018 |title=Herons of French Polynesia: threats, status and conservation |journal=Journal of Heron Biology and Conservation |volume=3 |url=https://www.heronconservation.org/wp-content/uploads/JHBC/vol03/03_02_Beaune_et_al.pdf |access-date=30 January 2020}}</ref> and Tonga<ref>{{cite journal |last1=Steadman |first1=David W.|date=1993 |title=Biogeography of Tongan birds before and after human impact |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=90 |issue=3 |pages=818–882 |doi=10.1073/pnas.90.3.818|pmid=11607357|pmc=45761|bibcode=1993PNAS...90..818S|doi-access=free }}</ref> – though it does not breed in Niue.<ref name="Watling" /> Surveys of the Fijian island of Rotuma, conducted in 1991 and 2018, suggest that the Pacific reef heron has recently colonized the island.<ref>{{cite journal |last1=Cibois |first1=Alice |last2=Thibault |first2=Jean-Claude |last3=Watling |first3=Dick |date=2019 |title=Birds and bats of Rotuma, Fiji |url=https://www.birdsnz.org.nz/wp-content/uploads/2021/12/Cibois_66_etal_139-149_-_3.pdf |journal=Notornis |volume=66 |issue=3 |pages=139–149 |doi=10.63172/745764bxiojf }}</ref>

New Zealand is considered to be the southern limit of the Pacific reef heron's distribution.<ref>{{cite journal |last1=Bell |first1=Mike |date=2010 |title=A census of reef herons (''Ardea sacra'') in the Marlborough Sounds |url=https://www.birdsnz.org.nz/wp-content/uploads/2021/12/Bell_2010_0.pdf |journal=Notornis |volume=57 |issue=3 |pages=152–155 }}</ref> Despite being relatively uncommon, the herons are found throughout the country, though are most common in Northland.<ref>{{cite book |last=Chambers |first=Stuart |date=2009 |title=Birds of New Zealand: locality guide |edition=3rd |url=http://nzbirdsonline.org.nz/sites/all/files/EGRSAC_Chambers.pdf |location=Orewa, New Zealand |publisher=Arun Books |page=91 |archive-date=28 December 2021 |access-date=30 January 2020 |archive-url=https://web.archive.org/web/20211228065151/https://nzbirdsonline.org.nz/sites/all/files/EGRSAC_Chambers.pdf }}</ref>

== Behaviour and ecology ==

=== Breeding === The species lay clutches of eggs year-round in colonies in the jungle, between palms and mangroves or in cavities of old buildings. Two to three paled greenish-blue eggs are laid in nests constructed from branches and blossoms. Males and females share brooding tasks. They normally have a 28-day brood period. After chicks are hatched, parents provide approximately five weeks of support.<ref name=NZBO/>

=== Food and feeding === Their food sources are made up predominantly of varieties of ocean-based fish, crustaceans, molluscs and worms.<ref name=NZBO>{{cite web |url=http://nzbirdsonline.org.nz/species/reef-heron |title=Reef heron ''Egretta sacra'' |publisher=New Zealand Birds Online |access-date=29 May 2021 }}</ref> This heron hunts during both day and night, depending on the rise and fall of the tides. During the day, it hunts in shallow waters; standing motionless with wings open like an umbrella to reduce reflections and create shade which attracts fish.<ref>{{Cite web |title=Pacific or Eastern Reef Egret |url=https://www.oiseaux-birds.com/card-pacific-eastern-reef-egret.html |access-date=2024-09-25 |website=www.oiseaux-birds.com}}</ref>

== Conservation status == In New Zealand, the Pacific reef heron has the conservation status of "Nationally endangered". It has been classified as "Regionally Critical" in the Wellington Region.<ref>{{Cite report|last1=McArthur|first1=Nikki|last2=Ray|first2=Samantha|last3=Crowe|first3=Patrick|last4=Bell|first4=Mike|date=August 2019|title=A baseline survey of the indigenous bird values of the Wellington region coastline|url=https://www.gw.govt.nz/assets/Our-Environment/Environmental-monitoring/Environmental-Reporting/Wellington-coastal-bird-survey-report-July-2019-v4.pdf|page=19}}</ref>

== Gallery == <gallery> Pacific reef heron (Egretta sacra) dark morph Rarotonga.jpg|Dark morph, Rarotonga, Cook Islands Eastern Reef-Egret96.ogg|Mooloolaba, Australia Juvenile Reef Egret.jpg|Juvenile dark morph, Coral Bay, Western Australia Pacific reef heron (Egretta sacra) dark morph in flight Rock Islands.jpg|Dark morph, Palau Pacific reef heron (Egretta sacra) light morph in flight Rock Islands.jpg|Light morph, Palau </gallery>

== References == {{Reflist}}

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Category:Egretta Category:Birds of Southeast Asia Category:Birds of the Pacific Ocean Category:Birds described in 1789 Category:Taxa named by Johann Friedrich Gmelin Category:Articles containing video clips