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). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not 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 for this species has not been directly quantified, but evidence from across its range suggests populations are stable to increasing. In Tanzania, surveys in 1995 found African Fish-eagles at a density of 4 birds/km along the shoreline of the south west corner of Lake Victoria, with an additional 621 birds on Rubondo Island. The overall Tanzanian population may equal 15,000 - 20,000 individuals (N. Baker, in litt. 2020). At Lake Hawassa in Ethiopia, surveys in 2018 found 47 individuals along a 16km transect, indicating that the Rift Valley lakes in Ethiopia could harbour hundreds or even thousands of breeding African Fish-eagles (E. Buechley in litt. 2020). Similarly in Kenya, surveys between 2010-2018 indicated that populations in the Rift Valley there were increasing (P. Gacheru in litt. 2020). In 2017, at Lake Naivasha, 245 adults were observed over 68km of shoreline, and more recent surveys have found more than 300 mature individuals (S. Kapila in litt. 2020). In South Africa, reporting rates increased by 43% between SABAP1 in 1987-1992 and SABAP2 in 2007-2020 (D. Ogada and P. Shaw, in litt. 2020).
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
Behaviour This is an afrotropical species (17°N to 35°S), common to abundant throughout its range except in waterless areas. It is generally sedentary but can be nomadic in response to resource shortages (e.g., drought, flood or prey scarcity), and has been recorded traveling up to 200km from the natal site (Ferguson- Lees and Christie, 2001). Habitat The species occupies a range of aquatic habitats from sea level to 4000m, ideally areas of calm water, such as swamps, lakes, rivers, floodplains and estuaries. Juveniles that are dispersing can cross vast dry areas and will roost and feed on carcasses en-route (Ferguson- Lees and Christie, 2001; del Hoyo et al., 1994). Diet The species’s diet consists primarily of fish, but it will also take other available taxa as well as carrion when prey is scarce. Juveniles are known to feed at large mammal carcasses alongside vultures and Tawny Eagles (Ferguson- Lees and Christie, 2001). In Zimbabwe they have adapted to preying on the invasive alien species Nile Tilapia (Oreochromis niloticus) and Largemouth Bass (Micropterus spp.) (N. Deacon in litt. 2020). Breeding Site The species nests near water, in tall acacias or other suitable trees, and occasionally on rock outcrops. Nests are up to 1.5m in diameter and are composed of sticks and papyrus, lined with rush heads and occasionally, weaver nests. Breeding can occur at any time within Equatorial regions, but spans April - October in southern Africa; June - December in the east; and October – April in the west (Ferguson- Lees and Christie, 2001). They have even been observed nesting in urban areas (N. Deacon in litt. 2020).
The species is not known to be directly persecuted by humans, even though it is very numerous and probably a direct competitor for fish. Neither is it particularly affected by habitat loss. In some regions a build-up of organochlorine pesticides in water bodies and therefore in their fish prey, could result in eggshell thinning. This has been recorded in South Africa (Ferguson- Lees and Christie, 2001) and Zimbabwe (del Hoyo et al., 1994) but has not yet had any significant impact on the population, and they seem to have benefited from the proliferation of farm dams. Current threats include pressures from the increasing human population, such as degradation of water quality, and development of shoreline habitat (E. Buechley, in litt. 2020). In Zimbabwe, an emerging threat is the increase in artisan gill-net fisheries, which use non-biodegradable nylon mono-filament gill-nets. There has been an increase entanglements, and observations of individuals with gill-net fragments wrapped around their feet and legs. Unregulated artisanal gill-net fishing on inland waters is increasing in most southern African countries (N. Deacon in litt. 2020).
Text account compilers
Baker, N., Buechley, E., Deacon, N., Gacheru, P., Kapila, S., Ogada, D., Shaw, P., Westrip, J.R.S., Butchart, S., Harding, M. & Ekstrom, J.
BirdLife International (2023) Species factsheet: Haliaeetus vocifer. Downloaded from http://www.birdlife.org on 22/03/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/03/2023.