The IUCN-SCC Heron Specialist Group

Journal of Heron Biology and Conservation
Volume 4, Article 1 (2019)

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

Douglas M. HarebottleDepartment of Biological and Agricultural Sciences, School of Natural and Applied Sciences, Sol Plaatje University,
Private Bag X5008, Kimberley, South Africa;


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.


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.

Appendix 1
Appendix 1. The 31 colonial waterbird species that were considered in determining colonial sites for this study. Nomenclature after Gill and Donsker (2018); global status taken from IUCN (2017). LC = Least Concern, VU = Vulnerable, EN = Endangered. Country codes: BW – Botswana, CV – Cape Verde, GM – The Gambia, KE – Kenya, LS – Lesotho, MG – Madagascar, ML – Mali, NA – Namibia, SZ – Eswatini (formerly Swaziland), TZ – Tanzania, UG – Uganda, ZA – South Africa, ZW – Zimbabwe. Heronries in Senegal and Mauritania did not report any species specific information and are therefore not included here.


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.

Appendix 2
Appendix 2. Sample data Excel forms that were made available to observers for the collection of heronry data for this study: (a) The first version of the data form that was used in the early part of the study; (b) A streamlined modified version of (a) and is the current version that is used.

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.


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).

Table 1
Table 1. Summary of the status of heronry sites in Africa based on submitted and additionally sourced data to HeronryMAP:Africa. The estimated number of breeding pairs is based on available nest count data for active sites only and should be regarded as preliminary estimates. Regions are based on those defined by the African Union (http://www.west-africa-brief.org/content/en/six-regions-african-union): N = Northern, S = Southern, E = Eastern and W = Western. Data sourced over a three-year period, 2014-2016.

Figure 1
Figure 1. Spatial distribution and protective status of 336 heronry sites throughout Africa based on HeronryMAP:Africa data. Protected sites are those located in formally protected areas; partially protected sites are those which are or form part of Important Bird Areas or Ramsar Sites; Unprotected sites are those sites which are known to occur outside of formally protected areas; Unknown refers to sites for which no information was available to determine protective status. Dashed lines indicate boundaries separating the five regions in Africa (see Table 1). The numerical values refer to the number of sites in each region.

Appendix 3
Appendix 3. Photos of selected colonies included in the HeronryMAP:Africa database.

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.

Figure 2
Figure 2. Spatial distribution and type of human-wildlife impacts of 336 heronry sites throughout Africa based on HeronryMAP:Africa data. Hunting refers to killing of adult birds at nest sites; Mixed impacts refers to any combinations of known impacts and Unknown refers to colonies where there are no data available on conflict scenarios. Dashed lines indicate boundaries separating the five regions in Africa (see Table 1). The numerical values refer to the number of sites in each region.


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).


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

Borrow, N. and R. Demey. 2010. The birds of Ghana. Bloomsbury, London, U.K.

British Trust for Ornithology. 2018. Heronries census. [online] Accessed 20 August 2018.

Brooke, M. and T. Birkhead 1991. The Cambridge encyclopedia of ornithology. Cambridge University Press, Cambridge, U.K.

Brown, L. H., E. K Urban and K. B. Newman (eds.). 2002. The birds of Africa. Volume 1. Christopher Helm, London, U.K.

Clancey, P. A. 1997. The birds of southern Mozambique. African Bird Book Publishing, Westville, South Africa.

Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan and C. L. Wood. 2017. The eBird/Clements checklist of birds of the world: v2016. [online] Accessed 25 August 2018.

Cox, W. A., A. Schwarzer, R. Kiltie, A. Paul, M. Racha, K. D. Meyer, J. J. Lorenz, P. E. Frezza, H. Rafferty, G. M. Kent and S. Roebling. 2017. Development of a survey protocol for monitoring Reddish Egrets (Egretta rufescens) in Florida, USA. Waterbirds 40: 334-343.

del Hoyo, J., A. Elliot and J. Sargatal (eds.). 1992. Handbook of birds of the world. Volume 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.

Dodman, T. 2014. Status, estimates and trends of waterbird populations in Africa: AEWA-listed African populations. (CSR6 African populations). Wetlands International Wageningen, The Netherlands.

Gawlik, D. E., R. D. Slack, J. A. Thomas and D. N. Harpole. 1998. Long-term trends in population and community measures of colonial-nesting waterbirds in Galveston Bay Estuary. Colonial Waterbirds 21: 143-151.

Gill, F. and D. Donsker (eds.). 2018. IOC World bird list (v8.1). [online] Accessed 15 November 2018.

Grant, K. R. and J. Watson. 1995. Controlling nuisance egret and heron rookeries in Oklahoma. Great Plains Wildlife Damage Control Workshop Proceedings. Paper 435. [online] Accessed 12 December 2018.

Hafner, H. and M. Fasola. 1997. Long term monitoring and conservation of herons in France and Italy. Colonial Waterbirds 20: 298-305.

Hancock, J. and J. A. Kushlan. 1984. The herons handbook. Croom Helm, London, U.K.

Harebottle, D. M. and D. Gibbs. 2004. Colour-ringed waterbirds in the southwestern Cape. Promerops 258: 9-10.

Harebottle, D. M. and D. Gibbs. 2006. At what age do African Sacred Ibis breed? Promerops 265: 13.

Harebottle, D. M., H. Smit-Robinson and A. Froneman. 2019. National guidelines for interventions that relate to colonial breeding waterbirds causing human-wildlife conflict in South Africa. [online] Accessed 20 June 2019.

Harrison, J. A 2005. Sticks ’n stones: building for birds. Africa - Birds & Birding 10: 52-59.

Harrison, J. A., M. McIver and M. Weyers. 2001. Weyers Islands: a successful design for constructed heronries. Bird Numbers 12: 40-43.

Harrison, J. A., A. J. Williams and M. MacIver. 2010. Breeding site selection by colonial waterbirds given various combinations of constructed or natural alternatives over a 10-year period. Ostrich 81: 197-203.

Hong Kong Bird Watching Society. 2016. Egretry Counts in Hong Kong with particular reference to the Mai Po Inner Deep Bay Ramsar Site – Summer 2016 Report. [online] Accessed 22 March 2018.

IUCN (International Union for the Conservation of Nature). 2017. The IUCN Red list of threatened species. Version 2017-2. [online] Accessed 1 December 2017.

Kopij, G. 2014. Distribution and numbers of breeding cormorants (Phalacrocoracidae) and herons (Ardeidae) in Lesotho. South African Journal of Wildlife Research 44: 189-192.

Kushlan, J. A. 1993. Colonial waterbirds as bioindicators of environmental change. Colonial Waterbirds 16: 223-251.

Kushlan, J. A. 2007. Conserving herons. A conservation action plan for the herons of the world. Heron Specialist Group and Tour de Valat, Arles, France.

Kushlan, J. A. and H. Hafner. 2000. Heron conservation. Academic Press. London, U.K.

Kushlan, J. A. and J. A. Hancock. 2005. The herons. Oxford University Press. New York, New York, U.S.A.

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliot, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, B. Sydeman, J. Trapp, J. Wheeler and K. Wohl. 2002. Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Waterbird Conservation for the Americas, Washington D.C., U.S.A.

Little, I. T. and C. Theron. 2014. Guidelines for custodianship in South Africa, rewarding conservation friendly farming. Unpublished report of the Endangered Wildlife Trust, Johannesburg, South Africa. [online] Accessed 27 June 2019.

Maddock, M. and G. S. Baxter. 1991. Breeding success of egrets related to rainfall: a six-year Australian study. Colonial Waterbirds 20: 133-139.

Maccarone, A. D., J. N. Brzorad and H. M. Stone. 2010. Nest-activity patterns and food-provisioning rates by Great Egrets (Ardea alba). Waterbirds 33: 504-510.

Marchant, J. H., S. N. Freeman, H. Q. P. Crick and L. P. Beaven. 2004. The BTO heronries census of England and Wales 1928-2000: new indices and a comparison of analytical methods. Ibis 146: 323-334.

Mashiko, M. and Y. Toquenaga. 2018. Site fidelity in lineages of mixed-species heron colonies. Waterbirds 41: 355-364.

Matsunaga, K. 2018. Changes of the nesting sites of Grey Herons (Ardea cinerea) in Hokkaido, northern Japan. Journal of Heron Biology and Conservation 3(1): 1-7. [online] Accessed 15 November 2018.

McKilligan N. 2005. Herons, egrets and bitterns. Their biology and conservation in Australia. CSIRO Publishing, Collingwood, Victoria, Australia.

McKinley, D. C., A. J. Miller-Rushing, H. L. Ballard, R. Bonney, H. Brown, S. C. Cook-Patton, D. M. Evans, R. A. French, J. K. Parrish, T. B. Phillips, S. F. Ryan, L. A. Shanley, J. L. Shirk, K. F. Stepenuck, J. F. Weltzin, A. Wiggins, O. D. Boyle, R. D. Briggs, S. F. Chapin, D. A. Hewitt, P. W. Preuss and M. A. Soukup. 2017. Citizen science can improve conservation science, natural resource management, and environmental protection. Biological Conservation 208: 15-28.

Newman, G., M. Chandler, M. Clyde, B. McGreavy, M. Haklay, H. Ballard, R. Scarpino, R. Hauptfeld, D. Mellor and J. Gallo. 2017. Leveraging the power of place in citizen science for effective conservation decision making. Biological Conservation 208: 55-64.

Perennou, C., N. Sadoul, O. Pineau, A. R. Johnson and H. Hafner. 1996. Management of nest sites for colonial waterbirds. Conservation of Mediterranean wetlands – Number 4. Tour du Valat, Arles, France.

Rabarisoa, R., J. Ramanampamonjy, F. Razafindrajao, L-A. Rene De Roland, F. Jeanne and O. Bacar (in review). Status assessment and population trends of the Madagascar Pond-heron (Ardeola idea) (Hartlaub, 1860), 1993-2016. Waterbirds.

Redman, N., T. Stevenson and J. Fanshawe. 2011. Birds of the Horn of Africa - Ethiopia, Eritrea, Djibouti, Somalia and Socotra. Revised and Expanded Edition. Princeton University Press, Princeton, New Jersey, U.S.A.

Richardson, A. J., I. R. Taylor and J. E. Growns. 2001. The foraging ecology of egrets in rice fields in southern New South Wales, Australia. Waterbirds 24: 255-264.

Rush, S. A., C. Pekarik, D. V. Weseloh, F. Cuthbert, D. Moore and L. Wires. 2015. Changes in heron and egret populations on the Laurentian Great Lakes and connecting channels, 1977-2009. Avian Conservation and Ecology 10(1): 7. [online] Accessed 27 June 2019.

Spies, R. B. and T. Weingartner. 2007. Long-term change. Pages 259-418 in Long-term ecological change in the northern Gulf of Alaska (R. B. Spies, ed.). Elsevier, Amsterdam, The Netherlands.

Stier, A. 2018. Studies of the Agami Heron in French Guiana. In Weseloh, D. V. C. and M. C. Green, (eds.). Research summaries from the Herons of the World Symposium; 2016. Journal of Heron Biology and Conservation 3(5): 10-11. [online] Accessed 3 December 2018.

Sullivan, B. L., T. Phillips, A. A. Dayer, C. L. Wood, A. Farnsworth, M. J. Iliff, I. J. Davies, A. Wiggins, D. Fink, W. M. Hochachka, A. D. Rodewald, K. V. Rosenberg, R. Bonney and S. Kelling. 2017. Using open access observational data for conservation action: A case study for birds. Biological Conservation 208: 5-14.

Tarboton, W. R. 1977. Status of communal herons, ibis and cormorants on the Witwatersrand. South African Journal of Wildlife Research 7: 19-25.

Telfair II, R. C., B. C. Thompson and L. Tschirhart. 2000. Nuisance heronries in Texas: characteristics and management. Second Edition. [online] Accessed 20 September 2018.

Turner, D. 2002. Herons in Africa and the Malagasy region. Pages 123-150 in Heron Conservation (J. A. Kushlan and H. Hafner, eds.). Academic Press, London, U.K.

Turner, D. 2011. Checklist and status of herons in East Africa. Journal of Heron Biology and Conservation 1(9): 1-8. [online] Accessed 20 September 2018.

Tyler, S. J. 2001. A review of waterbird counts in Botswana, 1991-2000. Babbler Special Supplement No. 1. BirdLife Botswana, Gaborone, Botswana.

Underhill, L. G., R. J. M. Crawford, D. M. Harebottle and K. M. C. Tjørve. 2009. The development of the heronry on Robben Island, Western Cape, South Africa, 1980-2005. Pages 217-221 in Final report of BCLME (Benguela Current Large Marine Ecosystem) project on top predators as biological indicators of ecosystem change in the BCLME. (S. Kirkman, ed.). Avian Demography Unit, University of Cape Town, Cape Town, South Africa.

Veen, J., H. Dallmeijer and C. Diagana. 2007. Monitoring colonial nesting birds along the West African Seaboard. Wetlands International Africa, Dakar, Senegal.

Veen, J., W. C. Mullié, C. M. Sylla, P. Robinson and M. S. Diop. 2011. Suivi de la reproduction 2011 des colonies d’oiseaux marins de l’Ile aux Oiseaux, Parc National du Delta du Saloum. Rapport interne soumis à la Fondation Internationale du Banc d’Arguin (FIBA) Dakar/Wenum Wiesel, August 2011. Dakar, Senegal.

Wetlands International. 2012. Waterbird population estimates, fifth edition. Summary report. Wetlands International, Wageningen, The Netherlands.

Whittington-Jones, C. (ed.). 2014. Humans and birds – A guide to problem resolution and mitigation. Endangered Wildlife Trust, Johannesburg, South Africa.

Yanosky, A. 2018. Heron conservation in Paraguay. In Weseloh, D. V. C. and M. C. Green, (eds.). Research summaries from the Herons of the World Symposium; 2016. Journal of Heron Biology and Conservation 3(5): 11-12. [online] Accessed 3 December 2018.