Archived 2020 topic: Martial Eagle (Polemaetus bellicosus): Request for information

BirdLife International factsheet for Martial Eagle.

The Martial Eagle occurs across a large range in Africa. The range stretches from sub-saharan Senegal in the west, to Somalia in the east, and down to South Africa in the south (BirdLife International, 2020). It inhabits sparse woodland and open habitats including deserts and grasslands (Kemp et al. 2020). The population size for this species has not been directly quantified. Between them, South Africa, Lesotho, Eswatini and Namibia are estimated to have <1500 pairs (Simmons, 2015; Taylor, 2015). Globally, it was estimated in 2001 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 (BirdLife International, 2020). As such, the Martial Eagle is suspected to be undergoing rapid declines, and has previously been considered Vulnerable under Criterion A2acde+3cde+4acde. However, new information regarding the rate of declines suggests 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 Martial Eagle is suspected to be experiencing rapid declines. The rate of decline is measured over the longer of ten years or three generation lengths of the species. The generation length for the Martial Eagle has recently been recalculated to 11.06 years (Bird et al., 2020)*. Rates of decline for this species are therefore calculated over 33.18 years.

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 0.8 to  0 birds/100 km) and a 50% reduction in the observation rate in National Parks (from 1.4 to 0.7 birds/100 km; Thiollay, 2006). Scaled across three generations (33.18 years), these rates of reduction would equate to a 100% reduction in unprotected areas and a 51% reduction in National Parks.

A comparison of roadside counts that took place in 1991-1995 and in 2015-2016 in northern Botswana detected a 36% reduction in the observation rate (from 0.14 to 0.09 birds/100 km) and reported a 52% decline, after controlling for variation in the lengths and distribution of survey transects (Garbett et al., 2018). Scaled across three generations (33.18 years), these rates of change would equate to reductions of 49% and 67%, respectively.

A comparison of roadside counts that took place between 1972 and 2012 in Kenya detected a 65% reduction in the observation rate in unprotected areas (from 0.23 to 0.08 birds/100 km) and a 133% increase in the observation rate in protected areas (from 0.53 to 1.24 birds/100 km; Ogada et al., in prep. a). Scaled across three generations (33.18 years), these rates of reduction would equate to a 58% reduction in unprotected areas and a 102% increase in protected areas.

However, new research into the rates of decline 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: 95% from 1969-1973 to 2003-2004 across Mali, Burkina Faso and Niger; 27% from 1972 to 2012 in Kenya; and 52% 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 6.1% per year. This would equate to a reduction of 88% over three generations (33.18 years).

An analysis of reporting rates for South Africa from the Southern African Bird Atlas Project (SABAP) 1 (1987–1992) and SABAP 2 (2007–2012) found a 59% reduction in mean reporting rate (from 7.3% in SABAP 1 to 3.0% in SABAP 2; Amar & Cloete, 2018). Scaled across three generations (33.18 years), this rate of change would equate to a reduction of 77%.

Data from a considerable part of the large range is lacking. While high decline rates have been reported from several countries, Mali, Niger and Burkina Faso now appear to form a small part of the range, both in geographical and population terms (BirdLife International, 2020; The Cornell Lab for Ornithology, 2020), and it is unclear whether these rates of reduction there are truly representative of the range-wide situation. While Botswana, Kenya and South Africa currently have higher observation rates (and therefore are assumed to represent a greater percentage of the existing population), encounter rates for Martial Eagle during the 1970s were higher in Mali, Niger and Burkina Faso. In South Africa and Botswana, the three-generation reduction rates are well over the Endangered threshold (≥50% three-generation declines). In Kenya the overall decline was smaller, while there is evidence to suggest that the species is now heavily dependent on protected areas.

More data from other countries is needed to substantiate the level of decline of this species. If the majority of the global population is following similar patterns to South Africa and Botswana, then the Martial Eagle may qualify for uplisting to Endangered under Criterion A. We therefore seek recent information on population trends for the Martial Eagle throughout its range, particularly in countries such as Namibia, Zambia, Tanzania, Uganda and Ethiopia.

Criterion B: The EOO for this species is too large to trigger the threshold (EOO <20,000 km2) for threatened status under this criterion. The Martial Eagle may therefore be considered Least Concern under Criterion B.

Criterion C: The population size for this species has not be directly quantified. Globally 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 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 trigger or approach 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 meet 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 Martial 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 Martial Eagle against this criterion.

In order to comprehensively reassess the Red List status of Martial Eagle, 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.

References

Amar, A. & Cloete, D. (2018). Quantifying the decline of the Martial Eagle Polemaetus bellicosus in South Africa. Quantifying the decline of the Martial Eagle Polemaetus bellicosus in South Africa. Bird Conservation International 28: 363–374.

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: Polemaetus bellicosus. Downloaded from http://www.BirdLife.org on 30/04/2020

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.

Handbook of the Birds of the World, 2020, Contributions map for Martial Eagle Polemaetus bellicosus, available at https://www.hbw.com/species/martial-eagle-polemaetus-bellicosus, accessed 30/04/20

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., Boesman, P. & Marks, J.S. (2020). Martial Eagle (Polemaetus bellicosus). 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/53171 on 30 April 2020).

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.

Simmons, R.E. 2015. Martial Eagle Polemaetus bellicosus. In: Simmons, R. E.; Brown, C. J.; Kemper, J. (ed.), Birds to watch in Namibia: red, rare and endemic species, pp. 135-137. Ministry of Environment and Tourism, Namibia Nature Foundation.

Taylor, M.R. 2015. Martial Egale Polemaetus bellicosus. In: Taylor, M. R.; Peacock, F.; Wanless, R. M. (ed.), The 2015 Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland, pp. 113-115. BirdLife South Africa, Johannesburg, South Africa.

The Cornell Lab for Ornithology, 2020, Range Map for Martial Eagle Polemaetus bellicosus, available at https://ebird.org/species/mareag1, accessed 30/04/20.

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

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12 Responses to Archived 2020 topic: Martial Eagle (Polemaetus bellicosus): Request for information

  1. Jean Marc THIOLLAY says:

    I have no new data other than the ones included in the 2 papers of Ogada and al but many occasional counts made in several african countries during the last 10 years show the increasing rarity of Martial eagles, especially outside large national parks

  2. Richard S. Hatfield says:

    I am a Trustee of the Kenya Bird of Prey Trust and a PhD student at Wageningen University studying Martial Eagle ecology in Kenya’s Maasai Mara ecosystem. I am in support of up-listing Martial Eagles based on the sobering evidence provided above and my fieldwork on the species over the last 3 years. In my study area (~3000km2) there are between 20 and 25 Martial Eagle pairs. Average pair territory size in the Maasai Mara is approximately 175km2. Many of these pairs have territories on the edges of the protected area network, and our current data-set suggests that these edge pairs select strongly against human-disturbed habitats for nesting. The few pairs that have bred outside of protected areas are often persecuted by people at their nest site. This persecution occurs because of Martial Eagle depredation of lambs, goat kids and chickens. We have recorded several incidences of targeted poisoning of individual eagles in retaliation for depredation on domestic stock. As Martial Eagles require vast undisturbed home ranges with ample prey, it is highly unlikely they will persist in meaningful numbers in any habitats with increasing sedentary human populations.

  3. Our research team conducted >10,800km of raptor roadcounts throughout the extent of Ethiopia from 2010 – 2017 and, of 22,909 individual raptors recorded, we recorded only 6 Martial Eagles (0.026% of raptors observed; 0.00055 individuals/km). While these surveys were not specifically designed to sample Martial Eagles, and survey routes occurred across a range of suitable and unsuitable habitat for the species, I believe this evidence, coupled with the large and growing human population size, loss of habitat, and limited protection even within flagship national parks in the country, to be indicative of a small and highly endangered population of the species in Ethiopia.

  4. Our research team conducted >10,800km of raptor roadcounts throughout the extent of Ethiopia from 2010 – 2017 and, of 22,909 individual raptors recorded, we recorded only 6 Martial Eagles (0.026% of raptors observed; 0.00055 individuals/km). While these surveys were not specifically designed to sample Martial Eagles, and survey routes occurred across a range of suitable and unsuitable habitat for the species, I believe this evidence, coupled with the large and growing human population size, loss of habitat, and limited protection even within flagship national parks in the country, to be indicative of a small and highly endangered population of the species in Ethiopia.

    Evan R. Buechley, PhD
    International Program Director
    HawkWatch International

  5. Phil Shaw says:

    A provisional re-analysis of Southern African Bird Atlas Project data for Martial Eagle in South Africa, encompassing a slightly longer period (1987–1992 to 2007–2020), indicates a 65% drop in reporting rates. This is equivalent to an annual decline of 4.2%, and a projected decline of 76% over three generation lengths (33.2 years). The level of decline evident for South Africa is thus slightly lower than the composite figure obtained from road transect surveys in W Africa, Kenya and Botswana.

    Phil Shaw, Arjun Amar, Darcy Ogada

  6. Red List Team (BirdLife International) says:

    Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested by so many people in commenting. The window for consultation is now closed. We will analyse and interpret the new information and post a preliminary decision on this species’s Red List status on this page in early July.

    Thank you once again,
    BirdLife Red List Team

  7. Red List Team (BirdLife International) says:

    This comment was received by email from Megan Murgatroyd on 27th June, shortly before the forums closed. The information was taken into account during the making of the preliminary decision, and is now posted here for transparency:

    I am in agreement with the RedList Reassessment for Martial Eagles. The downward trends stated for the species in South Africa seem to also be reflected in our monitoring of the breeding performance of Martial Eagles in Kruger National Park from 2013 to date; whereby the breeding performance has been consistently poor and is not enough to maintain a stable population. There is also some evidence of loss of adult birds on monitored territories.

  8. Red List Team (BirdLife International) says:

    Preliminary proposal

    Based on available information, our preliminary proposal for the 2020 Red List would be to list Martial Eagle as Endangered under Criterion A2acde+3cde+4acde.

    There is now a period for further comments until the final deadline in mid-July, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from the initial proposal.

    The final 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN. The final publication date will be publicised by IUCN here: https://www.iucnredlist.org/assessment/updates

  9. As a asafari Guide in Malawi I can see Martial Eagles sightings in most protected areas often and spotting them soaring outside protected areas. I have been lucky most of Mobile Birding Tours I was covering all three regions we have n Malawi. I have observed spotting more juveniles than adults which is a very good sign. However in protected areas along Shire river are places where many juveniles are spotted often feeding on Nile Water Monitor Lizards. I can finally say in Malawi we still have them and are increasing in number. We do also have others sharing their photos of Martial Eagles taken them n various places even out side protected areas on social media like Facebook ets.

  10. In Tanzania we are still seeing juvenile Marshall’s outside PAs so there is still recruitment but no surveys/transects that I am aware of so we do not have any hard data. They wander and are widespread and will be seen daily throughout our large PAs but no hard data on threats outside of PAs. Maps available on request and raw data for anyone who wishes to analyse it.

  11. Red List Team (BirdLife International) says:

    The following comments were received by email from Gareth Tate:

    I do believe some of our current work on Martial Eagles in South Africa may provide a bit more of a balanced outlook on the SA population, although ultimately I strongly support the decision to up-list Martials to EN based on the trends across the species traditional strongholds.

    The Endangered Wildlife Trust initiated a new conservation project looking at Martial Eagles that build nests and breed on pylons that support high voltage transmission lines, running through the largely treeless, semiarid landscapes of the Karoo of South Africa. Since 2019, our work has identified a significant breeding population along 1750kms of powerlines surveyed, with 138 active nests recorded since the start of the project. This equates to a nest approximately every 12km of powerline surveyed (see figure below). This supports previous work Berndt et al., 2015, that predicts approximately a third of the national breeding population nests on Eskom structures in this region.

    The provision of artificial nesting sites in the form of transmission line towers is suspected to have facilitated, to some extent, the range expansion of the species. This finding, which is at odds with the generally held belief that the Martial Eagle is increasingly confined to large protected areas, has significant implications for our thinking around the conservation management of this globally threatened species. However, the long-term status and sustainability of the pylon-nesting population is currently unknown, particularly in terms of its population dynamics. While it certainly represents an important population, its relative size could well contribute to sustaining other marginal populations that would otherwise be declining. Alternatively, it may represent a sink population, whereby elevated mortality from electrocution or collision may be driving declines in the overall population. Certainly, records show that Martial Eagles are amongst the most impacted South African raptor species (excluding vultures) in terms of power line related fatalities.

    To unpack this fully, the EWT are currently investigating the dynamics (breeding, spatial ecology, dispersal, survival etc.) of this population to improve the long-term sustainable management and conservation of this species. We can only answer such key questions through the long-term study of the pylon-nesting population distributed over a wide spectrum of land-use types.

  12. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

    The final categorisation for this species has not changed. Martial Eagle is recommended to be listed as Endangered under Criterion A2acde+3cde+4acde.

    Many thanks for everyone who contributed to the 2020 GTB Forum process. The final 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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