BirdLife International factsheet for African Fish-eagle
The African Fish-eagle occurs across a large range in Africa. The range stretches from sub-saharan Senegal in the west, to Ethiopia in the east, and down to South Africa in the south (BirdLife International, 2020). It inhabits a range of aquatic habitats such as swamps, lakes, floodplains and estuaries (Ferguson-Lees and Christie, 2001). The population size is estimated to be >100,000 pairs (Ferguson-Lees & Christie, 2001).
The only known threat to this species is the potential egg-shell thinning resulting from the build up of organochlorine in their diet. While this was previously observed in South Africa (Ferguson-Lees and Christie, 2001) and Zimbabwe (del Hoyo et al., 1994), there was no evidence to suggest it was having a significant impact on the population. The population was therefore considered to be stable, and the species was subsequently listed as Least Concern.
However, new information suggests that in some areas of its range, the population of African Fish-eagles is declining, which may warrant a change in Red List status. Therefore, we have fully reviewed the species here against all criteria.
Criterion A – Declines have recently been reported for the African Fish-eagle. The rate of decline is measured over the longer of 10 years or three generation lengths of the species. The generation length for the African Fish-eagle has recently been recalculated to 12.3 years (Bird et al., 2020)*, meaning that trends should be assessed over 36.9 years (three generations) under this criterion.
A comparison of roadside counts that took place in 1969-1973 and in 2003-2004 across Mali, Burkina Faso and Niger detected a 100% reduction in the observation rate in unprotected areas (from 4.9 to 0 birds/100 km) and a 25% reduction in the observation rate in National Parks (from 2.8 to 2.1 birds/100 km; Thiollay 2006). Scaled across three generations (36.9 years), these rates of reduction equate to a 100% reduction in unprotected areas and a 28% reduction in National Parks.
A comparison of roadside counts that took place in 1973 and in 2004 in northern Cameroon detected a 98% reduction in the observation rate in unprotected areas (from 3.3 to 0.1 birds/100 km) and a 41% increase in the observation rate in protected areas (from 4.6 to 6.5 birds/100 km; Thiollay 2001, R Buij, unpublished data, in D. Ogada and P. Shaw in litt. 2020). Scaled across three generations (36.9 years), these rates of change equate to a 99% reduction in unprotected areas and a 51% increase in protected areas.
A comparison of roadside counts that took place in 1991-1995 and in 2015-2016 in northern Botswana detected a 52% reduction in the observation rate (from 0.25 to 0.12 birds/100 km) and reported a 63% decline, after controlling for variation in the lengths and distribution of survey transects (Garbett et al. 2018) Scaled across three generations (36.9 years), these rates of change equate to reductions of 71% and 81%, respectively.
In Kenya, during surveys in unprotected land between 1972 and 2012, too few birds were recorded to provide an estimate of change (Ogada et al., in prep. a).
However, new research into the rates of decline for this species is being conducted by Ogada et al., (in prep. b) who combined the changes in encounter rates described above, in protected and unprotected areas, weighted by the species’s range in each land use category, and within each country. This resulted in the following estimated reductions: 98% from 1969-1973 to 2003-2004 across Mali, Burkina Faso and Niger; 91% from 1973 to 2000 in northern Cameroon; and 63% from 1991-1995 to 2015-2016 in northern Botswana (Ogada et al. in prep. b). By weighting these reductions by the proportion of the species’s range within each survey areas, they estimated an overall rate of reduction of 9.5% per year. This would equate to a reduction of 97% over three generations (36.9 years). Data from a considerable part of the large range is lacking. While high decline rates have been reported from several countries, it is unclear whether the rates of reduction there are truly representative of the range-wide situation. Without more data from representative countries, it is difficult to gauge the full picture of the global decline rate. If sustained rates of decline are occurring across a wider area of its range, then the African Fish-eagle may warrant uplisting to a higher threat category. We therefore seek recent information on population trends for the African Fish-eagle throughout its range, particularly in countries such as South Africa, Zambia, Tanzania, Uganda, and Ethiopia. If this species is declining, we also seek information on the cause of declines. What are the threats, what are their trends, and how widespread are they?
Criterion B – The Extent of Occurrence (EOO) for this species is too large to trigger the threshold (EOO <20,000 km2) for threatened status under this criterion. African Fish-eagle may therefore be considered Least Concern under Criterion B1.
Criterion C – The population size estimate is too large to trigger the threshold for listing as threatened under this criterion (<10,000 mature individuals), and the African Fish-eagle is considered Least Concern under this criterion. The subpopulation structure for this species is unknown, and a greater understanding of population size and sub-population structure would be beneficial. We therefore seek up-to-date information regarding population size and subpopulation structure.
Criterion D: The global population size estimate is far too large to reach the threshold (<1,000 mature individuals) for classification as threatened, and so this species is considered Least Concern under this criterion. However, we seek up-to-date information on population size for African Fish-eagle.
Criterion E – To the best of our knowledge, no quantitative analysis of the probability of extinction has been done for this species. We therefore cannot assess the African Fish-eagle against this criterion.
To carry out a comprehensive reassessment of the Red List status of African Fish-eagle, we therefore ask for recent information on the population size and trend from as many African countries as possible, as well as on the subpopulation structure.
* Bird generation lengths are estimated using the methodology of Bird et al. (2020), as applied to parameter values updated for use in each IUCN Red List for birds reassessment cycle. Values used for the current assessment are available on request. We encourage people to contact us with additional or improved values for the following parameters; adult survival (true survival accounting for dispersal derived from an apparently stable population); mean age at first breeding; and maximum longevity (i.e. the biological maximum, hence values from captive individuals are acceptable).
Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’ Red List status. Therefore, please make sure your comments are relevant to the species’ Red List status and the information requested. By submitting a comment, you confirm that you agree to the Comment Policy.
An information booklet on the Red List Categories and Criteria can be downloaded here and the Red List Criteria Summary Sheet can be downloaded here. Detailed guidance on IUCN Red List terms and definitions and the application of the Red List Categories and Criteria can be downloaded here.
Bird, J.P., Martin, R., Akçakaya, H.R., Gilroy, J., Burfield, I.J., Garnett, S., Symes, A., Taylor, J., Şekercioğlu, Ç.H. and Butchart, S.H.M. (2020), Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology. online first view.
BirdLife International (2020) Species factsheet: Haliaeetus vocifer. Downloaded from http://www.birdlife.org on 05/05/2020
del Hoyo, J.; Elliott, A.; Sargatal, J. 1994. Handbook of the Birds of the World, vol. 2: New World Vultures to Guineafowl. Lynx Edicions, Barcelona, Spain.
Ferguson-Lees, J.; Christie, D.A. 2001. Raptors of the World. Christopher Helm, London
Garbett R; Herremans M; Maude G; Reading RP; Amar A. 2018. Raptor population trends in northern Botswana: a re-survey of road transects after 20 years. Biological Conservation 224: 87–99.
IUCN Standards and Petitions Committee, 2019. Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Committee. Downloadable from http://www.iucnredlist.org/documents/RedListGuidelines.pdf.
Ogada, D., Shaw, P., Virani, M.Z., Thiollay, J.M., Kendall, C.J., Odino, M., Patel, T., Wairasho, P., Dunn, L., Thomsett, S., in prep. a. Raptor declines in Kenya over the past 45 years.
Ogada, D., Shaw, P., Buij, R., Thiollay, J.M., Garbett, R., Herremans, M., Virani, M.Z., Amar, A., Maude, G., Dunn, A., and Thomsett, S., in prep. b. Continental declines of Africa’s raptors.
The Cornell Lab for Ornithology, 2020, Range Map for African Fish-eagle Haliaeetus vocifer, available at https://ebird.org/species/affeag1 accessed 05/05/20
Thiollay, J.M. (2001). Long-term changes of raptor populations in northern Cameroon. J. Raptor Res. 35: 173-186
Thiollay, J.M., 2006, The decline of raptors in West Africa: long-term assessment and the role of protected areas, Ibis, 148, pp. 240-254