BirdLife International factsheet for Bateleur
The Bateleur inhabits woodlands and tree savannah (Kemp et al. 2020), occurring across a large range in Africa. The range stretches from sub-saharan Senegal in the west, to Somalia in the east, and down to Botswana in the south (BirdLife International, 2020). The population size for this species has not been directly quantified, but in 2001 it was estimated to be ‘in the tens of thousands’ (Ferguson-Lees and Christie 2001).
This species is threatened by habitat loss, direct persecution, and the impacts of urban development (Ferguson-Lees and Christie 2001). As such, the Bateleur is suspected to be undergoing moderately rapid declines, and has previously been considered Near Threatened under the criterion A2acde. However, new information regarding the rate of declines suggest that the species may warrant a change in Red List status. Therefore, we have fully reviewed the species here against all criteria.
Criterion A – The Bateleur is suspected to be experiencing rapid declines. Under this criterion, the rate of decline is measured over the longer of 10 years or 3 generation lengths of the species. The generation length of the Bateleur has recently been recalculated to 15.3 years (Bird et al., 2020)*, so the appropriate trend period is 45.9 years.
A comparison of roadside counts that took place in 1969-1973 and in 2003-2004 across West Africa (Mali, Burkina Faso and Niger) detected a 100% reduction in the observation rate in unprotected areas (from 2.4 to 0 birds/100 km) and a 37% reduction in the observation rate in National Parks (from 18.5 to 11.6 birds/100 km; Thiollay 2006). Scaled across three generations (45.9 years), these rates of reduction equate to a 100% reduction in unprotected areas and a 48% reduction in National Parks.
A comparison of roadside counts that took place in 1973 and in 2004 in Northern Cameroon detected a 96% reduction in the observation rate in unprotected areas (from 2.5 to 0.1 birds/100 km) and a 65% reduction in the observation rate in protected areas (from 27.9 to 9.8 birds/100 km; Thiollay, 2001 in Ogada et al., in prep. a). Scaled across three generations, these rates of change equate to a 99% reduction in unprotected areas and a 79% reduction in protected areas.
A comparison of encounter rates in Kenya between 1972 and 2012 detected a 59% reduction in the observation rate in unprotected areas (from 1.2 to 0.5 birds/100 km) and a 38% reduction in the observation rate in protected areas (from 12.7 to 7.9 birds/100 km; Ogada et al., in prep. b). Across three generations, this equates to a reduction of 64% in unprotected areas and of 42% in protected areas.
In Botswana, encounter rates between 1993 and 2015 declined by 52% in unprotected areas (from 2.0 to 0.9 birds/100 km) and by 13% in protected areas (from 2.7 to 2.4 birds/100 km; Garbett et al., 2018 in Ogada et al., in prep. a). Across three generations, this equates to a reduction of 79% in unprotected areas and 26% in protected areas.
In a new study (Ogada et al., in prep. a), the reduction in the encounter rates across West Africa (per Thiollay, 2006), Cameroon (per Thiollay, 2001; R. Buij unpublished data in Ogada et al., in prep. a), Kenya (per Ogada et al., in prep. b) and Botswana (per Garbett et al., 2018) were combined across protected and unprotected areas. This results in a total rate of decline of 92% over three generations in West Africa, of 97% over three generations in Cameroon, of 53% over three generations in Kenya, and of 70% over three generations in Botswana. This study is further taking into account the differences in the proportion of the Bateleur’s global range that were covered in the above-mentioned studies and assigns different weights to the four different rates of population decline. The declines observed in West Africa (Burkina Faso, Mali and Niger) were weighted by a factor of 24 to account for the large area over which these declines were reported; the declines in Cameroon were weighted by a factor of 1; the declines in Kenya were weighted by a factor of 8, and declines in Botswana were weighted by a factor of 10 (Ogada et al., in prep. a). This results in an overall weighted decline of 85% of the populations in Mali, Niger, Burkina Faso, Cameroon, Botswana and Kenya (Ogada et al., in prep. a).
According to IUCN guidelines, data representing declines from a few subpopulations can only be projected onto the rest of the range if those subpopulations were by far the largest subpopulation three generations ago, or if it can be assumed that all the other subpopulations are declining at the same rate (IUCN Standards and Petitions Committee, 2019).
The subpopulation structure of the Bateleur is not fully understood, and data from a considerable part of the large range is lacking. Therefore, 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 other countries, it is difficult to gauge the full picture of the global decline rate. If the majority of the global population is following a similar pattern as above, with rates of decline >50% in three generations, the Bateleur may qualify for a higher threat category. We therefore seek recent information on population trends for the Bateleur throughout its range, particularly in countries such as Namibia, Zambia, Tanzania, Uganda, and Ethiopia.
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. The Bateleur may therefore be considered Least Concern under Criterion B1.
Criterion C – The population size for this species has not be directly quantified, although it was estimated in 2001 to be ‘in the tens of thousands’ (Ferguson-Lees and Christie 2001). However, owing to suspected declines, the situation may now be very different. The threshold for categorisation as threatened under this criterion is <10,000 mature individuals. If the population size is indeed still ‘in the tens of thousands’ then it would be considered Least Concern under this criterion. If however the population has undergone large declines, then it may approach or trigger one of the threatened categories under Criterion C. We therefore seek up-to-date information regarding population size and subpopulation structure.
Criterion D – If the global population is still ‘in the tens of thousands’ as estimated in 2001, then this is far too high to reach the threshold (<1,000 mature individuals) for classification as threatened, and would be considered Least Concern under this criterion. However, owing to recent suspected declines, we seek up-to-date information on population size for the Bateleur.
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 Bateleur against this criterion.
In order to comprehensively reassess the Red List status of Bateleur, we ask for recent information on the population size and trend from as many African countries as possible, as well as on the subpopulation structure.
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.
*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).
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: Terathopius ecaudatus. Downloaded from http://www.birdlife.org on 04/05/2020
Buij, R., Croes, B.M., Gort, G., and Komdeur, J., 2013, The role of breeding range, diet, mobility and body size in associations of raptor communities and land-use in a West African savannah, Biological Conservation, 166, pp: 231-246
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.
Kemp, A.C., Kirwan, G.M. & Christie, D.A. (2020). Bateleur (Terathopius ecaudatus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/53012 on 4 May 2020).
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. a. Continental declines of Africa’s raptors.
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. b. Raptor declines in Kenya over the past 45 years.
The Cornell Lab for Ornithology, 2020, Range Map for Bateleur Terathopius ecaudatus, available at https://ebird.org/species/batele1 , 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