Data Zone
Justification of Red List category
This species has a small population size, estimated to number less than 1,000 mature individuals. It is therefore assessed as Vulnerable.
Population justification
This species is described as fairly common to rare (Dutson 2011) and sparsely distributed (Woxvold and Novera 2021). Highest numbers appear to be in the New Georgia group where a minimum territory size of 10 km2 was estimated in relatively undisturbed coastal habitat on Kolombangara (Buckingham et al. 1995), and at least two pairs are thought to be resident on Tetepare (Read 2013). Four pairs were reported on the Three Sisters (12 km2) off Makira in the 1950s (French 1957). Birds are less common inland and on larger islands, e.g. Guadalcanal and Malaita (Cain and Galbraith 1956, Buckingham et al. 1995, G. Dutson pers. obs. 1997-1998), where numbers have declined within living memory (Buckingham et al. 1995, G. Dutson pers. obs. 1997-1998). On the basis of known records, descriptions of abundance and range size, the population is likely to number less than 1,000 mature individuals. Tentatively assuming a pair occurs approximately every 20-30km2 of coastal habitat, the population size is estimated at 455-683 mature individuals, placed here in the range 400-999 mature individuals.
Trend justification
A moderate and ongoing population decline is suspected on the basis of rates of habitat destruction and additional impacts of hunting. In the period 2000-2021, remote sensing data indicate that 7-9% of forest was lost in this species' range (Global Forest Watch 2022, using data from Hansen et al. [2013] and methods disclosed therein), equivalent to 13-15% in three generations (36 years; Bird et al. 2020). This is likely to accelerate (to an equivalent rate of 21-23%) in the future based on steeper losses in 2016-2021. Although this species hunts over open habitats including deforested areas, given its significant use and dependence on forest habitat for nesting (Buckingham et al. 1995, Dutson 2011), the reduction in forest cover extent is thought broadly to be causing an equivalent loss in the population size. This species is additionally impacted by hunting which is likely to compound declines.
Haliaeetus sanfordi is endemic to Bougainville and Buka, Papua New Guinea, and the Solomon Islands, where it occurs on most islands, excluding Rennell, including many tiny islets and reefs (Blaber 1990, Webb 1992, Buckingham et al. 1995, Cain and Galbraith 1956, Olsen 1997, G. Dutson pers. obs. 1997-1998, Dutson 2011).
It prefers forested coasts (G. Dutson pers. obs. 1997-1998, Read 2013) where it scavenges and kleptoparasitises Osprey Pandion haliaetus (Blaber 1990, Webb 1992, G. Dutson pers. obs. 1997-1998). Some pairs also hunt far inland and others, especially on the eastern islands, appear to have entirely inland ranges where they prey largely on northern common cuscus Phalanger orientalis and perhaps arboreal rats and fruit bats (Buckingham et al. 1995, Olsen 1997, J. Hornbuckle in litt. 1999). More commonly sighted coastally but close to forested habitat, the species favours old-growth forests over areas of plantation and secondary growth (Buckingham et al. 1995). Transect counts indicated a slight preference for lowland forests (primary and secondary), with hill forests also used (Buckingham et al. 1995). It has been observed along primary rainforest lined rivers and over peaks in montane forest at elevations of 1,100 m, away from freshwater lakes (Pikacha et al. 2012). This species makes significant use of primary forests (Buckingham et al. 1995) but also hunts over open habitats such as deforested areas where it is reported to scavenge dead mammals including feral dogs (G. Dutson pers. obs. 1997-1998). Other observed prey include Glossy Swiftlets Collocalia esculenta, Solomons Flying-foxes Pteropus rayneri, Prehensile-tailed Skink Corucia zebrata (Pikacha et al. 2012), eel (Hadden 2004), possum (Phalangeridae) (Olsen 1997, Olsen et al. 2006), Pacific Black Ducks Anas superciliosa, domestic cats and chickens (Olsen 1997, Olsen et al. 2006). The few nests that have been recorded have been located in mangrove forest or rainforest (Olsen 1994, 1997), and the only recorded active nest was found in an emergent tree in a near-coastal wetland within a mosaic of grassland and secondary forest (Petersson 2016). Breeding ecology of this species is poorly understood but observations of both parents bringing food to a nestling (Petersson 2016) suggests biparental care. The only record of an active nest reported a brood size of one, and a juvenile on the verge of fledging in mid-July suggests a hatching time of April and laying date of March (Petersson 2016).
It is threatened by forest degradation from industrial-scale logging, as well as agriculture and traditional gardening (Pikacha et al. 2012, Katovai et al. 2015). Remote sensing data indicate that forest loss is ongoing within this species' range (Global Forest Watch 2022, using data from Hansen et al. [2013] and methods disclosed therein). Silt run-off from logging and plantations are also likely to adversely affect it. Hunting is a recent threat with a breakdown of traditional taboos, especially in the lowlands of larger islands (Cain and Galbraith 1956, Buckingham et al. 1995, G. Dutson pers. obs. 1997-1998). The species was shot by European colonists, who influenced the indigenous people to kill eagles, for alleged predation on poultry and other domestic animals, and with the change from totemism (which revered the eagle) to westernised beliefs and practices (Olsen 1997, Debus 2017). Although still considered an important totem in many cultures (J. van der Ploeg in litt. 2020, Woxvold and Novera 2021), the species reportedly continues to be hunted (J. Bergmark in litt. 2022), and capture of eagles for sale in the illegal pet trade to urban business people in Honiara (presumably as status symbols) is also considered a threat (Pikacha et al. 2012). In addition, the Solomon Islands is a region of high malaria infestation. Control of this mosquito-borne disease with chemicals such as DDT may have affected H. sanfordi (Olsen 1994, 1997), although its use has now been phased out (Global Health Group & National Vector Borne Disease Control Program 2013). Climate change is a potential threat, with sea-level rise potentially leading to loss of habitat (Debus 2017).
Conservation Actions Underway
CITES Appendix II. The species is listed on Schedule 1 of the Wildlife Protection and Management Act 1998, which prohibits the export of the species without a permit. It is well-known to Solomon Islanders and is often featured in environmental articles and postage stamps. It has legal protection in some provinces. Recent initiatives are promoting its protection in inland community projects (van Oosten and Wyant 1999).
70-90 cm. Only large eagle in the Solomons. Plain or mottled brown plumage. In flight, the very short tail and rather pointed wings swept upwards in a deep "V" are distinctive. Similar spp. Immature Brahminy Kite Haliastur indus has similar plumage but is smaller and has different flight action. Pied adult White-bellied Sea-eagle H. leucogaster are obvious but immatures differ only in having darker breast than belly, and brown tail (blacker in H. sanfordi) soon developing white base. Voice Series of honking cackles. Hints Common around forested islets in the Roviana and Morovo lagoons.
Text account compilers
Vine, J.
Contributors
Dutson, G., Hornbuckle, J., Debus, S., Olsen, J., van der Ploeg, J. & Bergmark, J.
Recommended citation
BirdLife International (2024) Species factsheet: Sanford's Sea-eagle Haliaeetus sanfordi. Downloaded from
https://datazone.birdlife.org/species/factsheet/sanfords-sea-eagle-haliaeetus-sanfordi on 22/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/11/2024.