Waterbird Population Estimates for Herons

Below are the latest estimates of the numbers of heron in various populations. Depending on the species, estimates may be for the entire species, a subspecies, or a geographic population. These estimates were derived by Wetlands International in partnership with HeronConservation and others. The entire report with information on the processes used may be obtained through the search page of Wetlands International.

Estimates are in all cases only that, and base on the best information available and best professional judgment of those who know the populations best. As information increases, estimates will be updated. HeronConservation will continue to partner with Wetlands International and the Ramsar Convention in periodically updating these estimates. All are invited to participate in making these estimates more accurate. Please communicate your data and suggestions to the HeronConservation Co-chairs or Steering Committee Members.

Heron Population Estimates

Heron Red List

The Heron Red List as of 2020 is shown below.

This authority for the global classification of the conservation status of species is the IUCN. It is published periodically as the IUCN Red List of Threatened Species. BirdLife International is the listing authority for birds. HeronConservation partners with BirdLife International on its periodic assessments for herons. The Heron Red List is the same as the IUCN list. Like all species, herons may be classified the following categories, LC = Least Concern, NT = Near Threatened, VU = Vulnerable, EN = Endangered, CR = Critically Endangered, EW = Extinct in the Wild, and EX =Extinct. More information on the meaning of these categories may be found in the IUCN Red List Categories & Criteria document.

The IUCN process is conducted at the species level, whereas HeronConservation does its assessments at a population level. So for some species the classification of a species may differ from that of one or more of its populations. For information on the listing assessment process, please see the IUCN Website.

The IUCN Assessment in some cases identifies species, uses a listing order, and uses scientific and English names that are at times deviant from those used by HeronConservation. There are a number of reasons for these differences, mainly that HeronConservation, being concerned only with one group of species can tracks and implement changes within its group more readily, whereas IUCN needs to maintain a more conservative approach to such changes across its periodic assessments and needs to maintain a common global process. As there is not a problem in identifying which species is being referred to, HeronConservation has chosen to retain the IUCN order and names to maintain its consistency with the Global Red List.

HeronConservation will continue to partner with BirdLife in its evaluation of the status of heron species. You are welcome to participate in this process by communicating your data and information to the HeronConservation Co-chairs or Steering Committee Members.

List of the Herons of the World (IOC List ver. 10.2, in 2020)

The following is a list of the herons of the world based on IOC World Bird List, Version 10.2 (July 25, 2020).

Alphabetical list of abstracts for presentations

HeronryMAP:Africa - Mapping the distribution and status of breeding sites of Ardeids and other colonial waterbirds in Africa ^#

Abstract

Heronries in Africa are poorly studied and many data gaps are evident in terms of occurrence, species composition and productivity of these colonial breeding sites. This paper introduces HeronryMAP:Africa, a citizen-science project started in 2014 that aims to systematically collect long-term data on location, size and composition, site fidelity, longevity and conflict scenarios of heronries in Africa. Preliminary results are presented for current and historical sites sourced over a three year period (2014-2016). Three hundred and thirty-six colony sites were identified and mapped in 14 (25.9%) African countries; 72.6% of sites have no formal protection, 18.8% were subject to at least one human conflict scenario with ‘cutting of trees’ and ‘removal of trees’ being the most common human disturbances. A first, but presumably grossly underestimated total of 35,000 breeding pairs of colonial waterbirds in Africa is provided from available data. No species-specific nest data are given due to the tendency to report total nest numbers in mixed colonies rather than species-specific numbers. The study revealed a general paucity of data for heronries in Africa (there was no response from 74.1% of African countries), but also the challenges faced in collecting adequate scientific data for these sites. It did, however, show how citizen-science can make significant contributions to research projects that are poorly funded or have limited resources. Human-wildlife conflicts were highlighted as an area that is poorly understood for heronries but has important conservation outcomes. Future objectives include identification of species composition, assessment of priority sites, identification of conservation action for colonies under threat and production of an Atlas of African Heronries.

Key words: Africa; colonial waterbirds; heronries; HeronryMAP:Africa; human-wildlife conflict; monitoring.

# This paper was presented at the 1st Herons of the World Symposium at the 40th Anniversary Meeting of the Waterbird Society at New Bern, North Carolina, USA, 21-23 September 2016. Other papers from that Symposium have appeared in past (or will appear in future) issues of the Journal of Heron Biology and Conservation, and Waterbirds.

Introduction

Waterbirds that breed communally in freshwater or coastal systems are spread across eight bird families: Phalacrocoracidae, Anhingidae, Pelecanidae, Ardeidae, Ciconiidae, Threskiornithidae, Phoenicopteridae and Laridae (Perennou et al. 1996, Clements et al. 2017). Most of these waterbirds breed in large colonies, either loosely or in close association; however, some species are solitary nesters, e.g. Goliath Heron (Ardea goliath) and White-backed Night Heron (Gorsachius leuconotus) (Hancock and Kushlan 1984, del Hoyo et al. 1992). Colonies may be largely discrete (e.g., pelicans, gulls, terns and cormorants) or mixed (e.g., ibises, herons, egrets and spoonbills) (Hancock and Kushlan 1984, Perennou et al. 1996). However, some species such as the White-breasted Cormorant (Phalacrocorax lucida) and Reed Cormorant (Microcarbo africanus) are also known to frequently nest in extensively mixed flocks with Ardeids and Threskiornithids (DMH pers. obs.). The term ‘heronry’ usually refers to breeding sites where Ardeid species nest in mixed colonies (British Trust for Ornithology 2018); however, for the purpose of this paper, I will use this term to refer to breeding colonies for the colonial species concerned.

Due to their conspicuous behavior, abundance and often socio-economic and ecological impacts, the general distribution and basic biology of most of these taxa have been well studied globally (Hancock and Kushlan 1984, Brooke and Birkhead 1991, Kushlan and Hafner 2000, Kushlan and Hancock 2005). Continentally, studies are generally well distributed: in Europe (Hafner and Fasola 1997, Marchant et al. 2004, British Trust for Ornithology 2018), Asia (Hong Kong Bird Watching Society 2016, Mashiko and Toquenaga 2018, Matsunaga 2018) North America (Gawlik et al. 1998, Spies and Weingartner 2007, Maccarone et al. 2010, Rush et al. 2015, Cox et al. 2017), South America (Kushlan et al. 2002, Stier 2018, Yanosky 2018) and Australia (Maddock and Baxter 1991, Richardson et al. 2001, McKilligan 2005). However, gaps do exist and in Africa, information on the status and distribution of heronries is severely lacking; it is limited mainly to Southern and Eastern Africa (Tarboton 1977, Underhill et al. 2009, Turner 2011, Kopij 2014). Some data have been collected through atlas projects (Tanzania Bird Atlas; N. Baker in litt.), waterbird surveys (Botswana; Tyler 2001, Madagascar; Wetlands International 2012, Dodman 2014, Rabarisoa et al. (in review)) and some dedicated efforts of individual researchers (Turner 2002, J. Agutu unpubl. data, C. Barlow in litt.). However, most of these studies were short-term or of an irregular nature. Currently, only a single long-term monitoring program (1993 to present) for heronries in Africa is known to the author (Rabarisoa et al. (in review)). As a result, there is a gap in the knowledge of the importance of these African sites in terms of location, species composition, abundance, breeding productivity and site management (Perennou et al.1996, Kushlan et al. 2002).

HeronryMAP:Africa was born out of a heron banding project that started in 2002 in Cape Town, South Africa (Harebottle and Gibbs 2004, 2006) and the general paucity and limited nature of information on heronries in South Africa (Tarboton 1977, Perennou et al. 1996, Veen et al. 2011). The project was officially launched on 1 August 2014 through social media with the creation of a web page via Facebook - ‘HeronryMAP:Africa’.

The objective of this paper is to introduce HeronryMAP:Africa as a continent-wide, citizen-science based monitoring project for African heronries; preliminary results on the status and distribution of current and historical heronries in Africa are presented for 31 species (Appendix 1) and gaps in research and conservation interventions are identified and discussed.

Methods

The study area for this paper was the entire continent of Africa, the island of Madagascar and smaller offshore islands including Cape Verde, Madeira Islands, Zanzibar, Comoros, Sao Tome and Principe. Data were collected from various sources including surveys from ornithologists, heron researchers and bird club members; additional information was sourced from nest record cards (Animal Demography Unit, University of Cape Town; unpubl. data), academic or popular literature and from personal observations. The HeronryMAP:Africa web page was used extensively to request data and collate records and information about heronries throughout Africa, especially South Africa; all researchers and observers were encouraged to post records and upload images of active heronries. Standardized datasheets, available on the site, were provided for participants to use in uploading their data in a standardized format (Appendix 2). Any incidental information relating to breeding sites that was posted directly on the page was transferred to a database.

Data were grouped into current sites, 2012-2016, which had census data and historical sites, pre-2012 which included sites with census data and those which were reported as active but lacking census data. The reason for selecting 2012 as a cut-off to separate ‘current’ from ‘historical’ heronries is based on heronry dynamics; natural heronry sites generally persist for a few (2-3) years (due to natural variable landscape fluctuations or changes) before being abandoned (Perennou 1996, Underhill et al. 2009), therefore five years (prior to the final year of data gathering for this study, 2016) would be a reasonable amount of time to isolate recent, active colonies from older colonies that may have abandoned preferred sites and moved to other optimal sites.

Additional site protection status information and/or human-related conflict issues were sourced by the author where these were not or could not be provided by the respondent or observer.

Results

Spatial distribution and numbers

A total of 336 heronry sites was mapped from 14 countries across Africa (Table 1, Fig. 1); no distinction was made between colonies being mixed or discrete. Most records (n=238, 70.8%) were from southern Africa. Almost a quarter of the sites (n=73, 21.7%) were located in East Africa (including Madagascar), while 24 sites (7.1%) occurred in West Africa, including the Cape Verde Islands. Only one site (0.3%) was reported for Northern Africa (Mauritania, Table 1). No data were received from central Africa. Nearly half (45.8%) of localities (154/336) were recorded from South Africa; the next largest representations were from Kenya (32 sites), Uganda (29), Botswana (26), Lesotho (22), Zimbabwe (21) and The Gambia (21) (Table 1, Appendix 3).

Based on available data from submitted and sourced records for active heronries, a preliminary estimate of 35,000 breeding pairs was calculated from the 319 sites (out of 336 total sites) for which there were numerical data (Table 1); the estimate assumes that all historical sites (i.e. prior to 2012; n=162) have remained active with similar colony sizes that were initially reported. Seventeen sites were shown to be active prior to 2012 but lacked actual nest data. Most survey responders did not indicate any species specific numbers within a heronry; unfortunately, no verified species-specific breeding numbers are yet available in this study.

Protection status

Of the breeding colonies, 72.6% (244/336) were located in unprotected areas; 16.4% (55/336) of the sites were located in formal conservation areas (e.g. national parks or nature reserves) or included in Important Bird Areas and/or Ramsar Sites (Table 1, Fig. 1). The protection status for 37 colonies (11.1%) was ‘Unknown’.

Human-conflict coverage

Of the 336 sites, 81.3% (n=273) did not report any known human-wildlife conflicts; the remaining 63 sites (18.7%) had at least one known conflict (Table 1). From these 63 sites, the most frequently recorded conflicts included ‘cutting of trees’ and ‘removal of trees’. The distribution of human-conflict issues across all sites is given in Fig. 2; the current data indicate that Kenya and South Africa recorded most of the conflict scenarios identified.

Discussion

The results presented here are based on data sourced over a three year period and represent at least an initial attempt to document and quantify the numbers and distribution of heronries in Africa. However, it can be assumed that this is a gross under-estimation and under-representation of the real situation given the number of African countries (40 out of 54) for which no data were submitted in HeronryMAP:Africa but which probably have breeding colonies (see Clancey 1997 for Mozambique; Borrow and Demey 2010 for Ghana; and Redman et al. 2011 for Ethiopia, Eritrea, Djibouti and Somalia). This study also highlighted the challenges in collecting large-scale data on nesting colonial waterbirds across the African continent. Data are often insufficient or difficult to source, particularly when sites are known from personal experience (but not documented) or personal communication but where exact details cannot be ascertained in a timely manner. These gaps, as well as the identification of the species composition and updated status of historical sites with no data available, need to be filled in order to present a clearer and more holistic picture of the status, content and distribution of heronries across Africa. Dodman (2014) does include some information on breeding colonies for some species listed in this study but often locality details are lacking or information is vague. These data will need to be sourced so that these sites can be included in HeronryMAP:Africa and any future reviews of the dataset. Ongoing assessments and conservation measures remain limited without this information. The Heron Specialist Group of the International Union for the Conservation of Nature (IUCN) Species Survival Commission recognizes these gaps and has initiated an effort to establish a list of heron researchers in Africa in order to start building a database of heron researchers and to stimulate further development of research and projects on herons (C. King in litt.).

Although the distribution of documented heronries covers only a small number of African countries (n=14, 25.9%), the majority of records stem from southern Africa, and South Africa in particular. This has largely been due to the strong citizen-science networks in the region and the response of these volunteers to requests for information on heronries in the region. Most of these volunteers used social media to supply relevant information. Eastern Africa is the region which has the second largest number of documented heronries. There have been ongoing efforts there to document and update the status of herons in the region. Turner (2011) provided detailed accounts of the status of 19 Ardeidae in eastern Africa. The Tanzanian Bird Atlas (http://tanzaniabirdatlas.net/start.htm), which has now been underway since 1985, is providing valuable high-quality data for ardeid distributions and seasonality and has recently incorporated mapping active heronries into its volunteer operations (N. Baker in litt.). There are an estimated 50+ sites that have already been documented as part of the Tanzanian Bird Atlas with increasing numbers projected in the next five years (N. Baker in litt.). Western Africa has some data on heronries available through their coordinated waterbird monitoring programs (e.g. waterbird counts in Senegal and Mauritania, Veen et al. 2007) and through ex-patriots stationed in certain countries such as The Gambia (C. Barlow in litt.). Data are severely lacking from the rest of Africa, notably northern and central Africa, where up to nine and 26 species of ardeids, respectively, are known to breed (Hancock and Kushlan 1984, Brown et al. 2002).

This analysis has highlighted that only a small percentage (16.4%) of colonies are located in protected areas where sites can be protected from general human disturbance. Sites located on private land or public open spaces (e.g. parks and gardens) are subject to unpredictable threats such as human disturbance, including destruction of nests, egg predation and cutting or removal of trees. Considering most sites lack formal protection, conservation efforts for colonial waterbirds may need to be focused on private landowners in order to secure breeding sites across Africa and which may include landowner stewardship (https://www.capenature.co.za/care-for-nature/stewardship/) and custodianship programs (Little and Theron 2014).

The results of this study explicitly show that human-wildlife conflict scenarios are generally poorly understood or recognized for colonial waterbirds in the African landscape. Expansion of species and breeding sites into urban, suburban and rural areas often bring them into close contact with people and their associated activities (Telfair et al. 2000). These species/colony-human associations regularly lead to confrontation resulting mainly from the birds’ nesting and breeding activities and guano deposits posing nuisance factors and potential health risks. Many colonies are at risk; some are labelled nuisance sites due to excessive noise of breeding birds and potent guano smell (Grant and Watson 1995, Whittington-Jones 2014), while others are located close to airports or airfields creating potential collisions with aircraft as birds traverse the airfield to and from the colony (A. Froneman in litt.). Consequences of this are that colonies are usually destroyed (either through nest removal or tree cutting) without proper intervention or guidance from relevant authorities. There are no formal regulations or systematic guidelines in place to ensure that these situations are handled in a proper manner. In South Africa, however, Harebottle et al. (2019) have developed national guidelines to assist affected parties and provincial authorities in identifying and mitigating problematic colonies. Similar initiatives in other African countries, particularly where large heronries are under threat from human disturbance, should be considered. Nesting habitat enhancement has been carried out in South Africa (Harrison et al. 2001, Harrison 2005), by building artificial platforms for colonially nesting waterbirds. These have been constructed to replace natural sites that were not being used or were destroyed, and to attract species to breed in new areas. The platforms have been used to varying degrees of success but generally birds respond positively to these artificial nesting structures (Harrison et al. 2001, Harrison 2005). Management and maintenance of the platforms or structures are required to ensure sustainability of breeding populations on an annual basis. Mitigating human-wildlife conflict situations for colonial waterbirds may involve increased focus on constructing artificial breeding sites, particularly where threatened species are present and/or large, natural sites are under increasing threat (Perennou et al. 1996, Harrison et al. 2010).

The breeding pair estimates across all species within each country gleaned from this study should be interpreted cautiously. They are based solely on submitted information, and in light of missing data from other colonies, are gross under-estimations. At best, the figures given in this study should be regarded as an initial attempt to gauge the relative importance of breeding sites and abundance in each country. For colonial waterbirds, numbers of nests per active colony usually relate to breeding success (Perennou et al. 1996). This is driven largely by the number of pairs (within species and across species) that can build nests (nest site availability) and raise chicks. HeronryMAP:Africa will attempt to monitor breeding numbers and output as part of its long-term objectives.

Continued data collection, analysis and site assessments are critical to identify and document additional sites, determine their status and potential productivity, and assess the degree of risk to the future of the sites from habitat loss, climate change, human-wildlife-conflict and other conservation threats. The use of modern technology is crucial to collect high-quality data rapidly; this is important given the real possibility that, in the absence of any formal regulations, large and potentially important colony sites may be subject to disturbance and destruction. In South Africa, the development of mobile applications, such as BirdLasser (https://www.birdlasser.com) allows for project specific data to be collected; BirdLasser incorporates a HeronryMAP:Africa function which prompts users to add additional information (including colony name, breeding status of each species, etc.) when they log any of the species listed in Appendix 1.

Future long-term priorities for HeronryMAP:Africa will be to identify, census and prioritize sites at national and regional levels. This should be based on a set of criteria that will include the number of each species at the colony, conservation status of the site, species of greatest conservation need and threats to the colony. This will focus attention on important colonies and particularly those threatened by human disturbance. In addition, prioritization of heronries will enable conservation authorities to include these nesting sites in national or regional conservation planning programs. Kushlan et al. (2002) and Kushlan (2007) emphasize that where nesting habitat for colonial waterbirds is limiting, these habitats need to be protected and managed effectively to ensure survival of healthy populations. A broader landscape-habitat approach may need to be considered as part of the HeronryMAP:Africa project to ensure habitats and sites can be identified and managed, which may include the need to set up alternative, man-made sites; Perennou et al. (1996) and Kushlan et al. (2002) stress that the importance of artificial nesting sites should not be underestimated. In addition, the impact of climate change on wetland hydrology needs to be investigated as it may affect habitat quality, availability of nest sites and the timing of nesting and migration (Kushlan et al. 2002). Climate change may ultimately impact negatively on priority sites and birds may be forced to source alternative, potentially inferior sites as future breeding colonies. Kushlan (1993) identified colonial waterbirds as effective bioindicators of environmental change and HeronryMAP:Africa could be an effective data source to further elucidate how colonial waterbirds will respond to environmental change.

This study has highlighted the power of citizen-science and the use of social media in creating awareness and garnering biodiversity data for conservation outcomes. McKinley et al. (2017) and Sullivan et al. (2017) both highlight the importance of citizen-science and open access data in providing adequate information for species conservation action and natural resource management. Newman et al. (2017) argue that growth in technologies, particularly mobile applications, has the potential to expand the frontiers of social media and citizen-science to advance scientific research programs; they further elaborate that socio-cultural issues will likely influence citizen-science programs in the future as more biodiversity issues become linked to landscape and habitat changes. This is particularly relevant to this project as breeding sites may increasingly occur in local villages or areas of higher population densities resulting in potential human-wildlife conflict but also in opportunities for local citizen-science participation. In addition, access to social media platforms and technologies may be limited in parts of Africa (e.g. central and northern Africa) and which resulted in a lack of response and hence no data submissions for this study. Ultimately, long-term funding is pivotal to ensure that the HeronryMAP:Africa project can be effectively coordinated and managed into the future, where new or existing technologies for data collection can be implemented and coverage widened to include gap areas.

A long term outcome for HeronryMAP:Africa will be the production of an ‘Atlas of African Heronries’ which can serve as a valuable conservation resource. HeronryMAP:Africa, however, should be seen as an ongoing, long-term initiative to monitoring breeding populations of colonial waterbirds and species as well as implementing conservation action at both local and regional scales. The project also has the potential to provide improved species population estimates at country or regional levels which can contribute to Wetlands International’s Waterbird Population Estimates (Wetlands International 2012).

Acknowledgements

I am grateful to Dalton Gibbs for the inspiration during our early heronry ringing expeditions in Cape Town; this is where thoughts and ideas germinated. To all the people who responded to my requests for information, I am indebted to their input and timely response; without their submissions, data would be severely limited and outputs hampered. A special thanks to Don Turner for allowing access to his data and reports for eastern Africa, and Clive R. Barlow and The Gambian Department of Wildlife for data and information from The Gambia. I am extremely thankful to all the citizen-scientists who have joined the Facebook group, submitted photos, data and information and share a passion for heronries and heronry conservation; without their support this paper would not have been possible. Tabaro Kabanda kindly assisted with the production of the final maps. Lastly, I am indebted to Clay Green, Katsutoshi Matsunaga, Chip Weseloh and two anonymous reviewers for their input and comments that vastly improved the quality of the manuscript.

Literature Cited

Black Bittern

Ixobrychus flavicollis (Latham)

Ardea flavicollis Latham, 1790. Index orn., 2, p. 701: India.

Subspecies: Ixobrychus flavicollis australis (Lesson), 1831: Timor; Ixobrychus flavicollis woodfordi (Ogilvie-Grant), 1888: Solomon Isles, Aloa.

Other names: Yellow-necked Bittern, Mangrove Bittern in English; Avetorillo Negro in Spanish; Blongios à cou jaune in French; Schwarzdommel in German; Takasago-kuro-sagi in Japanese; Mangansile in Pilipino (Philippines); Kokokan sungai in Indonesian; Hei Yan in Chinese.

Description

The Black Bittern is a medium black or dark brown heron with a brown and white striped throat bordered by yellow.

Adult: In the male, the head and hind neck are dark grey black with a blue sheen. The relatively long bill is dark but variable. The upper bill is dark brown to red brown. The lower bill is pale green or purple below, but sometimes suffused with a reddish tinge with a yellowish tip. The irises are yellow to red brown and the skin around the eye is variable, dusky to green or pink. The chin, throat, neck and upper breast are deep buff streaked with black and white and bordered on each side by a paler gold yellow band from the chin to the base of the neck. A loose tuft of elongated feathers on the foreneck overhangs the upper breast. The back, tail and upper wing are grey black, with the wing coverts tipped in buff. The under parts are dark grey brown, often with a yellow wash. The legs are variable black, dark brown, or olive green with yellow green soles.

Variation: The female is slightly paler, generally brown grey instead of dark grey black, with more yellow wash to under parts. The female also has throat, foreneck, upper breast streaked with yellow, white and black with yellow breast plumes.

Birds vary individually and geographically. Individual variation is great. In Australasia, six plumage morphs have been recognized (Mayr 1945). All black and mostly white individuals have also been found (Payne and Risley 1978).

Described geographic variation is ascribed to three subspecies. Flavicollis, as described above, has the least amount of plumage variation. Compared to flavicollis, australis tends to be larger and variable. Males from Bismarck archipelago are mostly black with brown streaking on the throat and some females have brown grey under parts. Other morphs have been reported within this subspecies’ range. Compared to australis, woodfordi is slightly smaller, has a relatively longer bill, and males are darker below with narrow white streaks on breast and foreneck. Patterns of geographic variation are not clear given the vast amount of individual variation in the species.

Juvenile: The immature bird has a grey black crown, but appears duller with a rufous wash. The breast is brown streaked in yellow. Back feathers are edged in buff. Lores are green brown. Irises are yellow. Legs and feet are brown grey.

Chick: The downy chick is white with light brown tinge to neck and rump. The irises are black brown becoming dark brown. Bill, lores, legs and feet are light pink.

Voice: The “Whoo” is a low booming drum like call, a peculiarity of this species among the Ixobrychus bitterns. It is long, drawn out, rendered “ wh, o, o, o, o, o, o”, given at 15 s intervals and answered by neighboring birds. It undoubtedly is a territorial and advertising call. A soft “coo-oorh” call is given approaching the nest. Other calls have been reported but need to be clarified.

Weights and measurements: Length: Very variable, 55-65 cm. Weight: 275-358 g.

Field characters

The Black Bittern is identified by its size, dark back, striped neck bordered by a striking yellow streak, and its long bill. It is usually seen flying away into thick cover. It is distinguished from the other Ixobrychus bitterns by its dark back color with yellow neck and its larger size. It is distinguished from the Gorsachius night herons and the New Guinea Tiger-Heron by its uniformly dark plumage and disproportionately long dagger-like bill. It is distinguished from the Green Backed Heron by its uniformly dark upper parts, yellow patch and breast stripes.

Systematics

The Black Bittern is one of the Ixobrychus bitterns, but is the largest of the group. It is similar morphologically but uniquely has a booming call (Payne and Risley 1976). It also has a distinctive skull shape, related to its very long bill. It was previously assigned its own genus. Its skull and color pattern are most similar to the Dwarf Bittern.

Range and status

RANGE: The Black Bittern occurs in India, Southeast Asia, Indonesia, Philippines, Australia, New Guinea to the Solomon Islands.

Breeding range: The breeding range of flavicollis is Pakistan (Sindh), India (Jamdar and Srivastava 1990), Maldives, Nepal, Sri Lanka, Bangladesh, Myanmar, Thailand (Round 1992b, 1995, Lansdown et al. 2000), Cambodia, Vietnam, to central and south China (Yunnan, Hainan, Guangdong, Fujian, Taiwan, Hubei, Anhui, Shanxi), Malaysia (Sabah, Sarawak, Indonesia (Sumatra, Timo), Philippines. Australis occurs in Indonesia (Moluccas, Irian Jaya), Papua-New Guinea (including Bismarck archipelago), coastal Australia (north Queensland to New South Wales – Morris 1971). Woodfordi is confined to the Solomon Islands.

Nonbreeding range: Northern populations in China are migratory, wintering in western Malaya (peninsular, Sarawak), through Indonesia (Lesser Sunda Islands), and Philippines. There has been no recorded breeding in south west Western Australia since the 1950’s (Marchant and Higgins 1990).

Migration: Chinese birds move south in October to peninsular Malaysia, Greater Sundas and Philippines. Return is April- May. Post-breeding dispersal occurs and is likely the origin of island populations of this species. In India post breeding dispersal and drought based movements occur. A Malaysian bird has been recovered in India (Manipur) and an Indian bird was recovered in Maldives. Australian birds appear to be sedentary, but some regional movements occur. Dispersal records include Japan (Fukumoto et al. 1992), Christmas Island (Indian Ocean), Mollucas, Guam (United States).

Status: The status of the species is unclear. It is common in Pakistan, parts of India, and Sri Lanka. It is common and abundant in Myanmar and southeast China (Lansdown et al. 2000). It is widespread and not uncommon in east Australia but has declined over the past 50 years due to destruction of river edge habitat for farming, pastures and also because of salinization (Marchant and Higgins 1990, Maddox 2000). It is common in winter in Sarawak (Malaysia). It is uncommon in winter in Sumatra (Indonesia) and Philippines. It is widespread in New Guinea.

Habitats

This species typically uses thick scrubby vegetation, particularly forested streams and pools in permanent wetlands. But it uses a variety of habitats including swamps, mud flats, reed beds, wet forests, flooded bushy areas, marshes, forested streams, Pandanus fringed channels in swamps, Melaleuca swamps and coastal mangroves in Australia. Although primarily a lowland species, it occurs up to 1,200 m in India. It winters in reed beds around lagoons, pools and reservoirs in peninsular Malaysia and Borneo. It uses trees and reeds to rest and roost.

Foraging

The Black Bittern forages singly or as a pair in thick vegetation. It feeds by Standing with its neck and head pulled in and by Walking Slowly in Crouched or Upright postures (Recher et al. 1983). It also can scuttle agilely along mangrove roots and creep stealthily in a distinctive crouch. It feeds crepuscularly and also during the day when it is overcast or rainy.

They are seldom seen because they hunt in densely vegetated marshes and creek edges. When disturbed, it runs into cover or flies away. They roost when not foraging in reeds, trees or on the ground.

Food items recorded include relatively large fish, 12 to 115 cm long (Perca, Amniataba, Gobiomorphus), frogs, lizards, crabs, crayfish, shrimp, mussels, and insects including dragonflies, beetles, and flies.

Breeding

Nesting timing differs geographically. In the north, breeding is triggered by the advent of the monsoon, at any time between May and September. In Sri Lanka nests have been found in April, May in Java, February in New Guinea, and September to January In Australia. Overall it breeds in densely vegetated, secluded wetlands. But its nesting habitat is surprisingly diverse, depending mostly on having dense cover near water. In India and Sri Lanka, it nests in reeds, thorn bush or cane breaks low over water. In China, it nests in bamboo and trees as high as 6 m. In Australia nests are located in gums standing in water and in mangroves. It occasionally nests away from water and is it not unusual to nest close to human habitation.

Black Bitterns nest solitarily or in loose nesting groups. At places the nest interspersed in mixed colonies with other herons. The nest is a platform, 23-35 cm wide and 7.5 cm, with a shallow central depression. It is made of twigs or reeds. The nest is built by both birds. Its placement is variable, from 1 to 15 m above the water or ground.

Little is known about the courtship of this species. It adopts the Bittern posture when disturbed and when alarmed, raises and lowers its crest. It is likely that the plumes at the base of the neck are used during courtship display, but there is no information.

The eggs are white, although there have been reports of a blue tinge to some. As recorded, they vary in size averaging 41.6 x 31.4 mm in India and Myanmar, 45 x 35 mm in Australia, and 43 x 34 mm in New Guinea. Clutch size is 3-6 eggs. Although it is probably usually single brooded, double broods occur. Incubation is by both sexes. Both sexes feed the chicks regurgitated food. The incubating bird sits very tightly and the chicks. The chicks soon leave the nest if disturbed.
Nothing is known about late nesting.

Population dynamics

Nothing is known of the population biology and demography of this species.

Conservation

In Australia the species has declined owing to clearing for agriculture and the increasing salinity of the rivers. It was once common in southwest Western Australia but is not known to have bred there in 50 years. It is widespread elsewhere in Australia, but Garnett (1992) listed it under Taxa of Special Concern. In NSW it is listed (updated 1999) as Vulnerable under the NSW Scientific Committee Threatened Species Conservation Act 1995 and in Victoria its conservation status is classified as Critically Endangered (NRE 2000). The actual breeding distribution is little understood and not quantified. In many cases the range is based on a few observations. A basic conservation need is to clarify the breeding locations and distribution of the species and to locate the most important breeding areas.

Research needs

Patterns of geographic and individual variation are not clear. The variation in plumage and size in this species needs to be re-examined. There also is a need to clarify the status of the species throughout its range.

Overview

The Black Bittern is a forest bittern, a bird of thick cover, generally scrubby vegetation along mangrove shores and other watercourses. It is not a river heron in the sense of using running water, but thick vegetation along water courses appears to be a habitat requirement. It feeds in normal bittern fashion, but is relatively large for a ‘small' bittern. With its long bill and neck, it appears to be a fishing heron, working along the banks of watercourses from vegetation. It appears to take relatively large prey, and so may not eat large numbers of prey items per day. It likely feeds from territories, which it knows well and undoubtedly defends. Much remains to be learned about this heron.

Malayan Night-Heron

Gorsachius melanolophus (Raffles)

Ardea melanocephala Raffles, 1822. Trans. Linn. Soc. London 13, p. 326: western Sumatra (Probably near Bengkulu).

Other names: Malay Tiger Bittern in English; Martinete Malayo in Spanish; Bihoreau malais in French; Wellenreiher in German; Zuguro-mizo-goi in Japanese; Bakaw-gabi in Pilipino (Philippines); Kowak melayu in Indonesian; Helguan yan in Chinese.

Description

The Malayan Night-Heron is a small chestnut and brown nocturnal heron of low to mid elevation wet forests.

Adult: The crown and nape are black, ending in a long black crest. The bill is stocky, down-curved, dark brown above and green below. The lores and orbital skin are blue green. The irises are green yellow. The sides of the face and neck are rufous. The chin is white with a central row of black streaks. The back and upper wings are chestnut finely barred with black. The flight feathers are brownish-black with white tips, visible in flight. The tail is black. The underparts are dark brown finely speckled with black. Flanks and undertail-coverts mottled brown and white. The legs and feet are olive. During breeding the lores become blue. The males change well in advance of nesting whereas the female’s change during courtship (Chang 2000). After courtship the lores faded to blue green, green, to grey green.

Variation: The sexes are alike, but the male may have a longer crest and bluer lores in courtship (Tsao 1998). The species shows a high degree of individual variability in plumage. Previously three subspecies differing in plumage color were recognized, but their variability appears to be within the overall range of individual variation of the species. Geographic variation does occur however. Immature birds of the herons breeding on Palawan are buff heavily overlaid with black. Herons from the Nicobar Islands are small.

Juvenile: The immature is cryptically colored, strikingly different from the adult. Upper parts are dull grey to brown spotted and barred with white and buff. Under parts are white, spotted and barred brown. The crown is blackish barred and spotted with white.

Chick: The chick has not been described.

Voice: “Arh” call, rendered “arh, arh, arh” is the flight and interaction call. It also has hoarse croaks that are not yet characterized.

Weights and measurements: Length: 49 cm, Weight: 417-450 g.

Field characters

The Malayan Night-Heron is identified by its rufous neck, barred chestnut back, black cap with crest, and white tipped primaries. The Malaysian Night-Heron is distinguished from the Japanese Night-Heron by its chestnut brown (not darker body color), Black (not tawny) crown and longer crest, slightly longer thinner bill, and white (not tawny) tips on primaries. It is distinguished from the Cinnamon Bittern by its short stubby (not long and pointed) bill, black crown, blue green lores, larger size, barred cinnamon back (not plain cinnamon or brown with buff spots), black and cinnamon wings with white flight feather tips (not uniformly cinnamon). It is distinguished from all bitterns by its white wing tips and stout bill.

The immature Malayan Night-Heron is distinguished from the immature Rufous and Black Crowned Night-Herons by its short, stubby and downward-arched bill, smaller size, finer spotting on the back and wings, and mottled (not stripped) under parts. It is distinguished from the immature Striated Heron by its slightly smaller size, spotted (not plain) back, shorter stubbier bill, and green (not yellow) legs and feet.

Systematics

The Malayan Night-Heron is closely related to the Japanese Night-Heron. The relationships among the night herons are unsettled. Patterns of individual and geographic variation as is the appropriate subspecific taxonomy need to be clarified.

Range and status

The Malayan Night-Heron occurs in India, south east Asia, Philippines and the east Indies.

Breeding range: The Malayan Night-Heron breeds in India (west India, Assam and Manipur, Nicobar islands), Nepal, Thailand (north), Laos, Cambodia, Vietnam, (Cambodia not certain), south China (Hainan, Guangzhou, Taiwan – Sykes 1996, Yunan, Gaunxi, Kwangsi, Guangdong (Lansdown pers. comm.), the Philippines (including Palawan), and Japan (Ryukyu Islands). Recent information reporting immature birds in Malaysia (Peninsular, Taman Negra), Java, and Borneo suggests nesting, but this needs to be confirmed (Perennou et al. 2000, R. Lansdown pers. comm.).

Nonbreeding range: It occurs during non-breeding in west India (Perennou et al. 2000), Sri Lanka, Thailand, Laos, Cambodia, Vietnam, south China (Hainan, Guangzhou, Taiwan), Malaysia (Malay Peninsula, Sarawak), Indonesia (Sumatra, Java, Kalimatan, Halmahara, Talaud) (Coates et al. 1997), the Philippines (to Palawan), and Japan (Ryukyu Islands).

Migration: Because of it is a solitary species in difficult habitat away from surveys and bird watchers; its migration is not very well understood. Evidence exists for both migratory and sedentary habit in most populations, including west India, Nicobar, Indochina, south China, Taiwan, Philippines (including Palawan), and south Japan. It is likely that partial migration is the rule for the species, even in northern populations such as Taiwan and India, but this needs to be confirmed. Some west India birds migrate south in November–December through Sri Lanka (which is not the important wintering ground it once was thought to be), to Nicobar, Malaysia and across the Straits of Malacca, to Indonesia. East India, north Myanmar, and Thailand birds migrate south in August–October, presumably through Myanmar also to and through Malaysia to Sumatra, Java, and Borneo. Return migration through the Malay Peninsula is in April.

Whether post-breeding dispersal occurs in unclear. Birds have been seen outside the usual range, but not very far, (Shikoku Island), Palau Island, Indonesian islands (Bandai) and Christmas Island.

Status: No data are available on population sizes. Recent information suggests that the stronghold of the eastern population is in North Thailand, Vietnam and Laos (Perennou et al. 2000). It is uncommon throughout much of its range. It is uncommon and local in both seasons in Japan (Ryukyu Islands) (Wild Bird Society 1982), uncommon in nonbreeding season in Sri Lanka (Perennou et al. 2000), uncommon in both seasons in China (mainland, Taiwan – Sykes 1996), breeds throughout the Philippines but is uncommon in both seasons, rare in nonbreeding season in Java (McKinnon 1993).

Habitats

This is a heron of mature moist forests. It occurs in dense, high rainfall, subtropical forests ranging from the low wetlands, where it uses streams, marshes, and swamps, to moderate elevations, where it uses evergreen forests, secondary scrub and reservoirs. It occurs as high as 800 m in west India, 1,200 m in Thailand, 1,800 m in Sri Lanka, and 2,300 m in east India. It uses reed beds in migration and is often reported as making use of human environments, particularly flooded rice fields, pastures, and vegetable gardens and nesting near houses.

Foraging

The Malayan Night-Heron is nocturnal, although it feeds readily crepuscularly and by day as well. It is solitary forager that feeds by Walking slowly at the edges of water, fields and other feeding areas. Most observations are of its feeding in the open, but it is likely it feeds primarily unobserved under cover. In feeding on earthworms, it Probes them from the soil (Chang 2000). Little is reported on the details of its feeding behavior. It defends itself with Forward consisting of raised crest, open wings, and stabbing at the opponent. During the day, it roosts well hidden in reed, bamboo, and other dense vegetation. The diet is little studied. It eats terrestrial food, particularly earthworks and beetles but also mollusks, lizards, frogs, rarely small fish (Shen and Chen 1996).

Breeding

It nests in May–August during the big rains in west India, May–June in Assam, April–September in Taiwan. The night heron nests in lowland forests of tall trees and bamboo, usually near or over water. It nests in trees and also in reed beds. It is a colonial nester, with 20 nests close together. It also nests solitarily. The nest is a small fragile platform of sticks, sometimes lined with leaves and grass. Nests are placed well concealed in a fork of branches in trees, 5-10 m high over the water or bare ground. It occasionally nests in reed beds. Both birds of a pair build nests.

Nothing is known of the courtship and little is known of the nesting biology of this species. It appears to be typical that juvenile birds nest while still in juvenile plumage (Chang 2000).

The eggs are chalky-white with a slight greenish tinge and a single measurement was 46 x 37 mm. Clutch is usually 3, range 3-5. In Taiwan, a second clutch is laid after the first nesting is completed. Both parents incubate, which starts before the clutch is completed. Both parents also attend and feed the young. Young birds have been reported as helping at the nest in feeding the young, an unusual behavior in herons (Chang 2000). Young fledge at 43 days. Brood reduction occurred in Taiwan, with the youngest two chicks being ejected from the nest by the first hatched chick (Chang 2000). No quantitative information is available on nesting success.

Population dynamics

Birds in juvenile plumage nest, perhaps typically (Chang 2000). The observed nesting was in the months prior to molting in to adult plumage, so the birds were probably two years old, however the sequence of juvenile molts is not known. Nothing is known about the population biology of this species.

Conservation

Populations, except that of Nicobar, are vulnerable due to habitat loss (Heinz et al. 2000). The deficiency of data on this species is a critical impediment to conservation action. No doubt its habitat, like that of other Gorsachius herons, has been reduced due to deforestation and degradation. But the habitat needs of the species are not well understood, given that it is often reported to be using human-made habitats, and on Taiwan it nests in parks and near human residences (Chang 2000). It has been proposed that the species might be an indicator of environmental quality in wet tropical and subtropical forests, but this needs to be demonstrated (Perennou et al. 2000). Given its inaccessible habitat and secretive habits, it may be that the species is much more widespread and abundant than thought, particularly if it is accustomed to human-managed habitat as now is becoming clear in Taiwan. Intensive year-round surveys need to be conducted in suitable habitat in order to determine its status in various places.

Research needs

Much of the basic biology of the species remains to be determined. Information coming out of recent observations hints that the species may be of considerable biological interest. Nesting in juvenile plumage, helpers at the nest, and multiple clutches within a season are all very unusual among herons. This is a species that could reveal new elements of heron behaviour. Range-wide, year-round surveys of its annual occupancy of potentially suitable habitat need to be carried out to provide the basis for a conservation strategy.

Overview

The situation is much like that in the Japanese Night-Heron. So little is known of this heron that much of its basic biology is speculative and it is not certain what constitutes the essential characteristics of a nocturnal low- to mid-elevation wet forest heron.

Japanese Night-Heron

Gorsachius goisagi (Temminck)

Nycticorax goisagi Temminck, 1835. Pl. Col. Livr. 98, pl. 582: Japan.

Other names: Japanese Bittern in English; Martinete Japonés in Spanish; Bihoreau goisagi in French; Rotscheitelreher in German; Mizo-goi in Japanese; Bakaw-gabi in Pilipino (Philippines); Litou Yan in Chinese.

Description

The Japanese Night-Heron is a small, small billed chestnut and buff heron.

Adult: The Japanese Night-Heron has a chestnut cap with a short chestnut crest. The bill is relatively short and stout for a heron. The upper bill is dark brown; the lower bill is yellow. The irises are yellow and the lores are green yellow, forming a notable patch in front of the eye. The sides of the neck are buff brown. The upper parts are pale chestnut. The darker wings have blackish primaries with prominent broad tawny tips, giving the appearance of a black wing bar on an otherwise tawny wing. A pale patch on the forewing can be seen in good light. The under sides are brown with darker streaking and the flanks are slightly mottled. The legs are black green. In breeding, lores turn blue, and the bill turns green black.

Variation: The sexes are alike.

Juvenile: The immature is similar to the adult with a black brown crown and less chestnut head. Its neck is more spotted and streaked. Upper wings are paler.

Chick: The appearance of the chick has not been recorded.

Voice: A croaking “Buo” call, rendered “buo, buo” is the principal call in feeding and breeding. It is probably a contact and identification call.

Weights and measurements: Length: 49 cm.

Field characters

The Japanese Night-Heron is identified by its small size, tawny cap, short stout bill, and red brown upper parts. It is distinguished from the Malayan Night-Heron by its chestnut (not black) cap, shorter crest feathers, shorter and stouter bill, and tawny (not white) tips on primaries. It is distinguished from the Cinnamon Bittern by its bicolored back, chestnut wings and thicker bill.

Systematics

The Japanese Night-Heron is closely related to the Malayan Night-Heron. The relationships among these night herons are unclear.

Range and status

This night heron occurs in Japan, south China, and the Philippines.

Breeding range: The Japanese Night-Heron breeds only in Japan in Honshu, Shikoku, Kyusgu and on the Izu Islands.

Nonbreeding range: The overall range in spring and or summer is larger, but breeding has not been proven. It has bred in small numbers on Taiwan (Severinghaus 1989) but without recent record. Birds occur in spring and summer in east Russia (Primorye, Sakhalin) and South Korea (Gore and Won 1971). Some birds remain in Philippines in summer (Rand and Rabor 1960). These various spring and summer records suggest the possibility of breeding, but this needs to be proven.

In the northern winter, the heron occurs in south Japan (south Kyushu, Ryukyu Islands) and southeast China (Guangxi, Fujian, Zhejiang, Taiwan). Its principal wintering range appears to be the Philippines (Luzon, Semirara, Leyte, Negros, Panay, Siquijor, Mindanao, Palawan).

Migration: The Japanese Night-Heron is highly migratory. They move south at the end of October and occur widely trough Japan on passage. Some may remain in Kyushu but most move south through the Ryukas to and through China to the Philippines. Return is in March–May.

The species has some dispersal tendencies, possibly overshooting on southward or northward migration. It has occurred on Palau, Indonesia (Sulawesi, Halmahera), and Brunei (Borneo) (Elkin 1993). Given the paucity of records and difficulty of observing it, it should be sought after in these areas to determine if it might not be more regular than thought.

Status: The species is rare and extremely local in Japan. There is no population estimate available and it is not counted on surveys due to its secretive nature. Only 6 nesting sites are known (Lansdown et al. 2000). It is likely that the population numbers less than a few thousand birds (BirdLife 2001).

At the beginning of 20^th century it was common and remained relatively common into the 1940’s and 1950's. It disappeared from many traditional areas in the 1980’s and 1990's. Although it was reported to have bred in Taiwan, it is now a rare as a winter visitor and passage migrant there and in south China (Sykes 1996). It is rare but regular in South Korea. It is uncommon in the Philippines, which is probably its main wintering area (Dickinson et al. 1991).

HABITATS

This is a nocturnal forest heron. It is occurs in heavily forested rivers, streams, and swamps, in the low mountains. This habitat is now extremely scarce in Japan. Similar habitats appear to be used in the nonbreeding range (Sykes 1996). It occurs generally from 50-240 m in elevation, but has been reported as high as 1,500 m in Japan and 1,350 m in Philippines (with two records from as high as 2,400 m).

Foraging

The Japanese Night-Heron is primarily crepuscular, feeding solitarily or in small groups. It feeds by Walking slowly within the dense vegetation presumably along watercourses and pools but also on dry ground. It forages more rarely in the open. Habitats used include swamps, forest, farms, and rice paddies.

The diet appears to consist mainly of crabs and possibly other crustaceans, insects, earthworms, and small fish.

Breeding

The Japanese Night-Heron breeds in May–July. It nests in tall trees, 7-20 m tall. Species include cedar (Cryptomeria), cypress (Chamaecyparis), oaks (Quercus), zelkovi (Zelkova), and chestnut (Castanea). On migration in China it occurs in tall trees and bamboo forests along rivers and in the hills. The species nests solitarily. However in favorable situations these nests can be gathered within relatively close proximity (250-500 m), although not truly a colony. Nests are flimsy, crude platforms of sticks, placed on more or less horizontal and usually densely foliaged boughs, 7-20 m above ground.

Nothing is known of courtship display in this species, and little of its nesting habits. Incubating bird will adopt the Bittern Posture when alarmed. Eggs are dull white and measure on average 47.5 x 37 mm. The clutch is 3-4. The incubation period was estimated to be 17-20 days. Nothing is known about the hatching, growth, or breeding success of this species other than fledging occurs in 35-37 days. Late eggs found in July suggest renesting.

Population dynamics

Nothing is known of the population dynamics of the species.

Conservation

The Japanese Night-Heron is endangered (IUCN 2003). With only six confirmed and 15 possible breeding sites (Lansdown et al. 2000), the species is certainly under threat of extinction. If the 21 sites in Japan each supported 10 pairs, which is unrealistically high, the total known breeding population could be as few as 200 birds. It is certainly less than a thousand birds. Conservation of this species faces two great challenges: lack of information and destruction of the species’ habitat. The lack of information on the species constrains conservation action. The present status and distribution of the species must be determined as rapidly as possible. The 21 identified active and possible breeding sites should be re-examined for nesting, and those supporting nesting birds should be protected in a reserve system (Hafner et al. 2000). Threats to the known habitat of the species, both during breeding and non-breeding, are the principal conservation issues facing this species. In Japan, hill forests have been and continue to be deforested and converted to plantations. Remaining forests have developed a scrubby undergrowth (BirdLife 2001). Very little pristine forest habitat remains in Japan. Remnant stands need to be protected. Although the species is now found in degraded habitat, thoughts that this is an adequate habitat are probably incorrect. In the Philippines, lowland primary forest is similarly threatened by deforestation, rendering some areas totally unsuitable for the species. Protection of habitat on the wintering grounds is essential to the species’ conservation. Hunting may in the past have been a factor in its conservation. They have been found for sale in Taiwan in the 1970’s and Gorsachius herons have been confiscated in trade in the 1980’s. Introduced predators have led to its decline on islands.

A species action plan covering both breeding and non-breeding areas is desperately needed for the species.

Research needs

Research is difficult given the secretive nature and tenuous status of the species. None the less, much could be learned from observational study. So little is known about the biology of this species, which represents an adaptive arm of the herons—a small nocturnal upland forest heron, that its basic biology needs to be understood and related to both conservation needs and heron biology. Surveys need to be conducted to locate breeding and wintering areas. Given the apparently small population size, any site with a few birds constitutes an important area for this species. These sites need to be identified and placed in a range-wide reserve network to be monitored, protected, and managed. The taxonomy of the night herons is not well understood, and a thorough analysis is needed.

Overview

Nearly nothing is known about the ecology of this rare and declining species. In fact, it is not understood what constitutes the basic ecological characteristics of a nocturnal forest heron. It is certainly a very rare species that has depended on a forested habitat that has been under severe threat on both the breeding and wintering areas.

White-eared Night-Heron

Gorsachius magnificus (Ogilvie-Grant)

Nycticorax magnifica Ogilvie-Grant, 1899. Ibis, p. 586: Five Finger Mountain, Hainan.

Other names: Magnificent Night-Heron in English; Martinete Magnifico in Spanish; Bihoreau superbe in French; Hainanreiher in German; Hainan yan in Chinese.

Description

The White-eared Night-Heron is a medium brown heron with a brown streaked breast and a white patch on the side of the head.

Adult: The adult male has a black crown with a brown black crest. The rest of the head is distinctly patterned in white and brown patches. A brown black cheek patch extending from the crown to the bill is separated from the cap by a white wedge extending back from the eye - the white ear of the species’ common English name. A smaller white line descends diagonally from the eye. The chin is white and the upper throat also is white, but dusky centres to the feathers results in a mottled appearance. The irises are yellow, and the lores and skin around the eye are yellow green forming a conspicuous pale patch in front of the eye. The bill is basically dark, the upper bill being black and lower bill having a green yellow tinge at the base.

The front of the throat is vertically streaked down the middle, blacker towards the head and browner onto the breast. Three broad vertically oriented patches cover the area of the side to back of the neck: lateral to the dark-mottled central throat stripe is a white line descending from the white of the lower cheek, lateral to that is a broad black brown line ascending from the dark shoulder, and lateral to that is a broad buff yellow patch merging to chestnut orange at the back.

The upper parts are dark grey brown with a purple tinge, sometimes with a few white spots on the lower back. Flight feathers are slate. The brown stripe on the foreneck merges on the breast onto the mottled brown and white undersides. Thighs are dark reddish-brown. The legs are green.

Variation: In the female, the color of the head and neck is less prominent; the back and wings are more mottled, streaked, and spotted with white especially on the upper wing. The crest feathers are shorter than the male's

Juvenile: The immature has brown instead of brown black feathering spotted with buff or white. The back and upper wings are brown with heavy buff or white spotting.

Chick: The chick is undescribed.

Voice: Nothing is known of the voice of this species

Weights and measurements: Length: About 54 cm.

Field characters

The White-eared Night-Heron is identified by its dark base color contrasting with white ears and white throat, and by its short bill. It is distinguished from the Malayan Night-Heron by its tricolored neck (not rufous), dark (not chestnut) sides, and slate (not black) flight feathers. It is distinguished from the Black Bittern by shorter, thicker bill, stouter appearance, and shorter neck.

Systematics

The White-eared Night-Heron is related to the Japanese Night-Heron, Malayan Night-Heron, and the larger night herons. The relationships among the night herons remain unclear.

Range and status

The present known range of this species is confined to China,

Breeding range: This is a species with the most restricted known breeding range of any heron. Surveys conducted in 1999-2001 have clarified the current status. These have been organized through the collaboration of the Heron Specialist Group and Kadoorie Farm & Botanic Garden (KFBG), a conservation charity based in Hong Kong (KFBG, H. Hafner, and O. Pineau pers. comm.). Based on these surveys at present, there are known two breeding site in the world, both located in south Guangxi Province, and one other area where breeding is strongly suspected, located in neighbouring Guangdong Province.

Migration: It is most likely that this species is sedentary (BirdLife 2001). However information is very uncertain. There are winter and spring records from its most recent breeding area in south China (Hubei, Fujian, Guangdong, Guangxi). There also is a suggestion that dispersal occurred to the north prior to southern movement and that Hainan is or was once a wintering area for birds from further north. Of course given the population’s precarious position, its presence in Hainan has not been documented in recent years. There is one record from north Vietnam, which is either a straggler or an indication of prior wintering area.

Status: Very few individuals have been reported over the past 30 years. Of the two known breeding sites, one near Fusui is highly degraded and is unlikely to support the heron for much longer. In the early 1990’s the species was present in Hubei Province, in the Shennongjia Nature Reserve, but a re-examination of the site in 2001 revealed that what was prime habitat has been converted into a reservoir, and both the habitat and species have disappeared (KFBG, O. Pineau, and H. Hafner pers. comm.). In 2000 and again in 2001, the bird was seen in Guangdong Province in the Chebaling Nature Reserve suggesting another breeding site exists there. Since 1990, there have been only 7 confirmed observation locations; but, other than noted above, it has not been observed in recent years in other parts of its historic range in south China or Hainan (Zhou 1996, Fellows et al. 2001, Gao et al. 2000, BirdLife International 2001, Hafner pers. comm.). There are no population figures, but the world population numbers fewer than 20-50 birds. Certain remote areas in south China not yet surveyed need to be visited in a near future. In these forested mountain habitats difficult to access, isolated breeding sites may have gone unnoticed so far. This is the most endangered of all the herons (Kushlan and Hafner 2000).

Habitats

The White-eared Night-Heron is a forest bird. Optimal habitat appears to be extensive, dense, primary forests with streams and adjacent marshes. It currently is observed only in mid-altitude mountains and has not been found higher than 1,300 m. However, it likely was originally also a lowland species, and its current restriction to hilly areas is probably because there are no remaining lowland forests (Fellowes et al. 2001).

Given that very little pristine habitat remains within the historic range of the species, it is observed primarily in degraded habitats in and near forest reserves. Recent observations have been near streams, a reservoir, and rice fields, all feeding sites located within 40 km of subtropical forests. These observations do not necessarily suggest that it can survive long term in altered environments, but rather that it has been forced into these sites as more appropriate habitat is now lacking (BirdLife 2001).

Foraging

This is a very poorly known species. Observations of the species’ foraging are few (Caldwell and Caldwell 1931). Herons have been reported as feeding singly or in isolated pairs feeding on the ground in ways likened to a bittern. They roost high in trees. All evidence suggests that it feeds primarily at night, as it has been observed flying from roosts in the evening (Fellowes et al. 2001.). However daytime activity has also been reported (Zhou 1994). The diet includes fish, shrimp and insects, but is very little documented (Zhou 1994).

Breeding

Nearly nothing is known about the breeding biology of this species. Various records of nesting activity indicate it nests in trees including oaks (Quercus), pines (Pinus), bamboo (although a nest was not found) and, likely, broad leafed trees (Caldwell and Caldwell 1931, BirdLife 2001). Information on nesting by this species is confounded by indications that it nested with Malayan Night-Herons. Presumed nests were very near the tops of the trees, 4-10 m above the ground near the trunks. Presumed nests were simple flat platforms (Fellows et al. 2001).

Population dynamics

With nothing known about nesting, there is also no information on population biology.

Conservation

The White-eared Night-Heron is the world’s most endangered heron; immediate action is required for its conservation. It is clearly endangered (Kushlan and Hafner 2000 IUCN 2003). Fortunately, Guangxi and Guangdong Forestry Departments and county governments are strongly committed to conserving the species (Fellowes et al. 2001). In Guangxi, the Fusui White-eared Night-Heron reserve was declared in 1999. In that only two breeding sites are known thorough surveys need to continue and expand. The recent surveys in southeast China were important first steps in identifying locations where birds remain (Fellowes et al. 2001). The surveys began by canvassing the local population, gaining public involvement, providing publicity, and following this with ground surveys. This model could be followed to great benefit in other areas where the species is expected. Where sightings occur, immediate protection of the area should be envisaged. Specific conservation issues include hunting, deforestation, reintroduction, and education. Hunting is a threat to this species, apparently even in nature reserves. Young herons are captured for the market. In fact, discovering an animal for sale in a Nanning market sparked the current conservation effort (Lee 1998). Hunting pressure of all kinds is intense in the rural agricultural areas that constitute the species’ current range. Night herons (including both this and the Malayan Night-Heron) are trapped, shot, and noosed (Fellowes et al. 2001). In Fusaui, where empty night heron nests were found, villagers have reported that they killed adult birds at the nesting site the year before (BirdLife 2001). An immediate conservation effort should be undertaken to eliminate the use of this and other rare species to meet the strong local market demand for birds. This practice threatens all the herons in the area, especially those that nest colonially. The optimal approach would be to attempt to divert hunting from all the colonial species. The night heron is a nationally protected species in China.

The principal habitat threat to the species, in fact to other Gorsachius herons as well, is habitat loss, including deforestation, reforestation with pine monoculture, reservoir construction, and gold mining. Deforestation has been underway for centuries, and the remaining diverse forests are very confined, mostly in reserves. Most of the existing forest in the area is monoculture pine plantation. This species occurs in areas of south China recognized for their importance to a collection of endemic species, many of which are now endangered. Even in reserves, degradation and disturbance continue. Tourism is increasing in remaining reserved areas, also posing threats for this heron’s well-being. Another very important threat, especially to this nocturnal species, is the numerous electric power lines concentrated usually along streams because the streams provide openings in the forest facilitating the erection of the lines. To provide habitat, truly protected forest areas are essential. At the nature reserves where the species still occurs, specific management plans are needed, including control of tourism effects, forest management and restoration, management of river bottoms and marshes as feeding habitat, realignment of reserve borders, creation of reserve corridors, and protection from hunting. When new breeding sites are found, they and the feeding habitat will require absolute protection. These qualify as Important Bird Areas for the species and need to serve as the basis of a network of reserves, managed sites and other conservation efforts aimed to protect the remaining birds. To the extent possible, a captive breeding programme should be considered. Fellowes et al. (2001) recommended that no more birds be taken from the wild. However, birds that are rescued from market could form the core of a captive population which could be used to re-establish or enhance the wild stock as sites are protected. Educational awareness of the existence and plight of the species among local populations is essential. The campaign that accompanied recent field surveys leading to the establishment of a reserve is an excellent example of meeting such needs. The species will not likely be saved except by local people.

Research needs

Clearly, with nothing known about the biology of the species, observational studies should be undertaken at every opportunity, particularly focusing on establishing the habitat requirements of the species. Surveys of known and suspected areas used by the species need to be undertaken to identify additional important areas. In order to render these surveys more efficient in the future, any opportunity should be taken to record vocalizations, for instance by captive birds. Once vocalizations are known, the periodicity of calls during the year, the day, and the night should be established in the known breeding areas. Surveys of this secretive bird in other forest habitat could then focus on the periods and hours with the highest probability of hearing a call. It is essential that the migratory status and year-round habitat needs of the species be understood. The potential feeding sites within flying distance of possible colony sites need to be determined.

Overview

The White-eared Night-Heron is the most endangered of all the herons, and biologically nearly unknown. Only a few have been seen and reported in recent years, and the world population likely numbers not many more than are presently known. This is fundamentally a lowland forest heron, which occurred in dense, wet, primary lowland forests with streams and adjacent wetlands and rice paddies. This habitat hardly exists at present. Herons that persist due so at the edge of their ecological tolerances in secondary forest in hills and mountains near residual forests. This is a species that seems to not tolerate disturbance well, and so requires reserves. Where found now it feeds in rice fields and irrigation systems. When rediscovered, the birds were in demand for the market in the area they are found, and their rarity did not provided much protection. The only hope for the species is for its welfare to become a concern of the local human population, its nesting sites be completely protected from disturbance, and feeding sites secured. The only successful conservation for this species will be that provided by and in cooperation with the local people.

White-backed Night-Heron

Nycticorax leuconotus (Wagler)

Ardea leuconotus Wagler, 1827. Syst. Av., Ardea, No.3: Senegambia.

Other names: Martinete Encapuchado in Spanish; Bilhoreau à dos blanc in French; Weißrückenreiher in German.

Description

The White-backed Night-Heron is a nocturnal medium dark heron with a large white eye ring on a dark head and white plumes on an otherwise dark back.

Adult: The White-backed Night-Heron has a black head and a short, thick crest, strikingly setting off a large white patch around a relatively huge eye. The bill is black, with yellow its lower base. Irises are dark brown and the lores are green yellow. The chin is white and the neck is rufous brown. The back is black brown with white lanceolate plumes forming the dorsal patch, which is conspicuous at times and inconspicuous at others, probably related to breeding. The upper wings are brown; flight feathers are slate. Tail is black brown. The under parts are pale buff and brown; belly is white brown. Legs and feet are green to orange yellow. In breeding, irises turn red, chestnut, amber, yellow, probably in a sequence not yet described. The lores are lemon yellow.

Variation: The sexes are alike. Geographic variation is unclear, but South Africa birds have been described as natalensis.

Juvenile: Immature birds have dark brown streaked crown and forehead. Body is buff brown with heavy white streaking and speckling.

Chick: The chick is covered in olive brown down with buff feather tips. Bill is green grey. Irises are brown. Legs are green grey. Feet are yellow green.

Voice: The species is generally quiet. The growling “Taash” call, rendered “taash, taash, taash” is the disturbance call. The “Kroak” call is the alarm and flight call.

Weights and measurements: Length: 50-55 cm.

Field characters

The White-backed Night-Heron is identified by its relatively large, dark head and huge eyes

accentuated by the white eye ring and its white back patch. It is distinguished from immature Black Crowned Night-Herons by its smaller size, large head, white back patch, and more spotting on the back and wings.

Systematics

The generic identity of the species is not well settled. It has been variously assigned to Nycticorax and Gorsachius. The taxonomy of these night herons need to be further examined to determine both genus and species limits.

Range and status

The White-backed Night-Heron occurs in Africa, south of the Sahara.

Breeding range: It breeds widely from Senegal, Gambia, Guinea-Bissau, Cote d'Ivoire, Nigeria, Gabon, Sudan, Ethiopia, Congo, Tanzania, Uganda, Botswana, Zambia, Zimbabwe (Jonasi 1994), Malawi (Nyirenda 1992), Mozambique, north Angola, and east South Africa (Raymakers 1992).

Migration: The species appears to be sedentary, although it is likely that they undertake movements correlated with the onset of rains, but more information is needed on this secretive species.

Status: It is widely distributed through central and southern Africa but rare to uncommon. It may be most abundant in the Congo swamp forests and upper Zambezi in Zambia (Turner 2000).

Habitats

The White-backed Heron is a forest heron. It occurs in densely vegetated forests near water, especially along with tree-fringed streams, on islands in large rivers and lakes (Jonasi 1994), mangrove swamps along both African coasts, and forested lakes. It does also uses reed beds and dry forests. In places (Gabon) it is found close to human habitations, but this is not general.

As a nocturnal species, requiring secure day resting spots. It roosts in very dense marsh or forest vegetation, often high in trees.

Foraging

This appears to be very much a strictly nocturnal species. It has been observed feeding primarily at the water’s edge, along muddy banks, and in the reeds along water courses. It feeds by Walking slowly along and in shallow water and by Standing on vegetation such as rafts o floating reeds. It feeds alone or in pairs in and near dense vegetation. Both adults and young assume a bittern posture on disturbance (James 1988, Bock and Medland 1988). Its diet is little known but it does consume fish (Blasdale 1984), amphibians, mollusks, and insects.

Breeding

Breeding season is variable, usually at the height of the local floods, which varies from place to place, and time to time. It nests in July–January and also March–April in South Africa, August–December and also January–June in Tanzania, May–June in Kenya, September–October in Nigeria.

The White-backed Night-Heron nests low in trees, bushes, reed beds, and on rocky shores in caves (Edwards1988). It nests solitarily and nests are placed close to the water or ground. They are large and bulky platforms made of sticks or reeds lined with smaller pieces of the same material. They are 25-30 cm across. Nests are generally close to the water, usually within 1 m but sometimes 3 m. It also nests on the ground in reed beds.

Nothing is known about the courtship or nesting behavior. The eggs are green white, 45.7 x 35.1 mm. The are probably laid at intervals of 48 hours or more. Clutch is 2-3 eggs; range is 2-5. The herons will sometimes double clutch. Incubation is 24-26 days. The often young grow to considerable size before leaving the nest at 6-7 weeks old.

Population dynamics

Nothing is known about the population dynamics and conservation of this species.

Conservation

The White-backed Night-Heron is a widespread but scarce bird, and is secretive, making surveys and monitoring difficult. A first step in conservation is to determine the species’ distribution, habitat needs, and population status. This will require surveys throughout its range. The dependence of the species on swamp and riparian forests makes it vulnerable to the effects of harvesting of such forests throughout its range.

Research needs

Owing to its secretiveness, dispersed range, and difficult habitat this is one of the least understood herons. Studies are needed of its basic biology, including nesting, courtship (including the function of the dorsal plumes), foraging, food selection, dispersal, and habitat requirements. The evolutionary relationships of the night herons are not clear and a comparative study of the species is needed.

Overview

This night heron is a nocturnal, forest dweller that feeds secretively on the edges of cover tending to nest in the local flood season. Little is known about its feeding behaviours, food taken, or environmental correlates of foraging or nesting success.