Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is fairly large and hence it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The global population was previously thought to number c.1,000-10,000 individuals (Ferguson-Lees and Christie 2001). The population in China has been estimated at c.100-10,000 breeding pairs (Brazil 2009). In Australia, based on a population density of one pair per 40 km, the population is thought to number at least 500 pairs, but this is likely to be a significant underestimate (Department of the Environment 2020). In Hong Kong, 57 birds were thought to be present in 2010 (So and Lee 2010), with a recent estimate also of 15 breeding pairs (Y-T. Yu in litt. 2020). Based on several surveys along the Rakhine coast, Mawdin coast (south of Rakhine), Ayeyarwady delta, Mon State and Tanintharyi, the species is thought to be about 100-120 pairs in Myanmar (C. Zöckler in litt. 2020). In Singapore, 10-15 pairs have been reported (Y. Ding Li in litt. 2020). On account of its widespread occurrence, the overall population has also recently been considered to exceed 10,000 individuals (S. Garnett in litt. 2020). Based on all available information, the population size is here placed in the band of 2,600-41,000 mature individuals.
At least 3 subpopulations are also thought to exist in India (West Coast, East Coast, and the Andamans; S. Quader, Praveen J and A. Viswanathan in litt. 2020), however the overall population structure is unknown.
In Hong Kong, the population is also thought to have increased from 23 adults in 2003 (Siu-Tai et al. 2003) to 30 adults in 2009 (So and Lee 2010).
In Australia, the population size is thought to be declining, based on local declines and range contractions mainly reported in the 1980s and 1990s in New South Wales, Victoria, Tasmania and South Australia, although populations in the northern and remote tropical regions are thought to be stable (Department of the Environment 2020). In Victoria, the species is suspected to have declined due to the clearing of coastal forests for agricultural and urban expansion (Clunie 1994). However, an analysis of data from three Australian Bird Atlases found no significant difference in the spatial extent of occupancy between 1901-1976, 977–1981 and 1998–2001 (Shephard et al. 2005), and the reporting rate has been approximately stable since 2000 (BirdLife Australia 2020).
Recent information from the State of India's Birds (2020) suggests that the species has undergone a 72.59% decline in India in the past 25 years (C.I. 20.29%), which may equate to a reduction of 83% (C.I. 63-97%) over three generations (33.9 years). Over the last five years, an annual decline of 5.89% (C. I. 10.98%) has been estimated, which may equate to a reduction of 87% over three generations from 2015, but is highly uncertain. Further analysis of trends in India estimated a minimum decline of 12.23% between 2007-2018 and a best estimate of a 49.81% decline (S. Quader, Praveen. J and A. Wiswanathan in litt. 2020). These estimates may translate to a 33% and 88% decline respectively over a three-generation period.
Overall, there is little clear quantified evidence for a population decline (Y. Ding Li in litt. 2020). Accounting for significant declines within India or other localised declines, the overall population is nonetheless thought to be undergoing marginal reductions owing to human disturbance, shooting, poisoning, loss of suitable breeding sites caused by clearance of waterside forests and, possibly, over-use of pesticides (Ferguson-Lees and Christies 2001).
The species occurs throughout coastline regions in most of southeastern and eastern Asia, including India, Sri Lanka, the Andaman Islands, Bangladesh, Myanmar, Thailand, Malaysia, Brunei Darussalam, southern China, Viet Nam, Cambodia, Thailand, Singapore, Philippines, Indonesia, Timor-Leste, Papua New Guinea, and Australia and Tasmania. It is considered to be densely populated in Singapore (Y. Ding Li in litt. 2020). The Sundarban region is considered a possible stronghold in Bangladesh, and possibly all of South Asia (S. U. Chowdhury in litt. 2020). It is considered widespread on many coastal habitats of Myanmar (C. Zöckler in litt. 2020). The species is additionally considered widespread and common in Australia, with offshore breeding on the Abrolhos Islands, western Australia, with regular encounters of birds scavenging on roadkill (S. Garnett in litt. 2020, R. Davis in litt. 2020, S. Kittur, J. Grant and G. Sundar in litt. 2020, BirdLife Australia 2020). It is been deemed an uncommon resident on coastal regions of southern China however (including Hong Kong, Guangdong, Fujian, Hainan, Jiangsu, and Taiwan) (Siu-tai et al. 2003).
The species inhabits inshore seas, islands, coasts, mangroves, estuaries and terrestrial wetlands, but can occur in wooded and open habitats as well as lowland monsoon ranforests (Debus and Kirwan 2020). It occurs from sea level up to elevations of 1,500 m, but is common below 900 m. The species feeds on a wide range of prey, including fish, reptiles, birds, mammals, and carrion (Siu-tai et al. 2003). Nests will usually be found in forests, woodland (including nests on Ficus trees; Siu-tai et al. 2003), and rocky areas (Debus and Kirwan 2020). The species has also been considered to tolerate and even seek some types of human activity (such as typhoon shelters and fish culture zones; Siu-tai et al. 2003), as well as benefit from introduced prey rubbish dumps (Debus and Kirwan 2020). The species is however considered to have low recruitment rates (S. Balachandran in litt. 2020).
The species is thought to be threatened by habitat destruction, hunting, and poisoning by pesticides (Ferguson-Lees and Christie 2001). In Victoria, the species is suspected to have declined due to the clearing of coastal forests for agricultural and urban expansion (Clunie 1994). As observed by surveys in Hong Kong, the species's breeding success may also be susceptible to climatic change such as the increased likelihood of colder winters and cyclones (So and Lee 2010, S. Balachandran in litt. 2020). Theft of eggs and disturbance from grass cutting are also thought to have caused failure in breeding in the past (So and Lee 2010). Logging activities are considered to be a marginal threat in mangroves of Taninthary, Myanmar (C. Zöckler in litt. 2020). It may be deliberately trapped for the pet trade in Indonesia, albeit the exact scale is unknown (Y. Ding Li in litt. 2020).
Conservation Actions Underway
CITES Appendix II. It is protected under Schedule-I of the Indian Wildlife Protection Act of 1972 (State of India's Birds 2020). Nests are protected by the Wild Animals Protection Ordinance in Hong Kong, with the import and export of the species overseen by the Animals and Plants (Protection of Endangered Species) Ordinance (Siu-tai et al. 2003). The species is also listed in the China-Australia Migratory Birds Agreement. It is listed under the Hong Kong National Protection Class II (So and Lee 2010).
Conservation Actions Proposed
Carry out regular monitoring (especially during breeding season) and investigate the ecology of the species. Education and publicity programmes are required (Siu-tai et al. 2003).
Text account compilers
Fernando, E., Clark, J., Wheatley, H.
Balachandran, S., Butchart, S., Chan, S., Chowdhury, S.U., Davies, R., Ding Li, Y., Ekstrom, J., Garnett, S., Goes, F., Grant, J., Harding, M., Kittur, S., Praveen, J., Quader, S., Sundar, G., Viswanathan, A., Yu, Y. & Zöckler, S.
BirdLife International (2022) Species factsheet: Haliaeetus leucogaster. Downloaded from http://www.birdlife.org on 07/07/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 07/07/2022.