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Trade of threatened vultures and other raptors forfetish and bushmeat in West and Central Africa

R . B U I J , G . N I K O L A U S , R . WH Y T O C K , D . J . I N G R A M and D . O G A D A

Abstract Diurnal raptors have declined significantly inwestern Africa since the s. To evaluate the impact oftraditional medicine and bushmeat trade on raptors, we ex-amined carcasses offered at markets at sites (– standsper site) in countries in western Africa during –.Black kite Milvus migrans and hooded vulture Necrosyrtesmonachus together accounted for % of , carcasses com-prising species. Twenty-seven percent of carcasses were ofspecies categorized as Near Threatened, Vulnerable orEndangered on the IUCN Red List. Common species weretraded more frequently than rarer species, as were specieswith frequent scavenging behaviour (vs non-scavenging), gen-eralist or savannah habitat use (vs forest), and an Afrotropical(vs Palearctic) breeding range. Large Afrotropical vultureswere recorded in the highest absolute and relative numbersin Nigeria, whereas in Central Africa, palm-nut vulturesGypohierax angolensis were the most abundant vulture spe-cies. Estimates based on data extrapolation indicated thatwithin West Africa % of carcasses were traded in Nigeria,% in Benin and % elsewhere. Offtake per annum in WestAfrica was estimated to be –, hooded vultures, –palm-nut vultures, – Rüppell’s griffons Gyps rueppellii,–African white-backed vulturesGyps africanus, –lappet-faced vultures Torgos tracheliotos, and – crownedeagles Stephanoaetus coronatus. This represents a sizeableproportion of regional populations, suggesting that trade islikely to be contributing significantly to declines. Strongercommitment is needed, especially by governments inNigeria and Benin, to halt the trade in threatened raptorsand prevent their extirpation.

Keywords Bushmeat, commercial trade, diurnal raptors,traditional medicine, vultures, West and Central Africa

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Introduction

Wildlife is exploited throughout West and CentralAfrica (Martin, ). The trade in bushmeat (wild-

sourced meat) has been recognized as having a negative im-pact on wildlife populations in forests and savannahs(Njiforti, ; Fa et al., ; Lindsey et al., ), and itis estimated. billion kg of wild animal meat is traded an-nually in Central Africa (Wilkie & Carpenter, ). In add-ition to being exploited for bushmeat, many animals arehunted and traded specifically for use in traditional medi-cine, also known as wudu, juju or fetish (Adeola, ).The use of wildlife items for the treatment of a range ofphysical and mental diseases, or to bring good fortune,has been reported in almost every country in West andCentral Africa. Birds, mammals, reptiles and other taxaare sold at specialized fetish markets. However, many spe-cies are sold for fetish alongside those sold for their meat,or they are sold for either purpose, suggesting that the trad-itional medicine and bushmeat trades are probably inte-grated and to some extent interdependent (Saidu & Buij,; Williams et al., ). In urban settings the commercialtrade in wildlife-based medicinal products is often concen-trated in traditional markets, where various animals, includ-ing threatened species, are offered openly for sale. In a fewcountries such practices have become uncommon, but inBurkina Faso and Benin they represent a strong culturaltradition that is supported by the governments of thesecountries (Nikolaus, ).

The commercialization of biological resources often hasimportant conservation implications for heavily exploited spe-cies, especially those under pressure from other anthropogenicfactors, such as habitat loss (Alves et al., ). This is the casein many parts of West and Central Africa, where humanpopulation densities and growth rates are high, even bysub-Saharan African standards. Increases in human popula-tions contribute to high rates of land-use change and exploit-ation of wildlife, which also occurs frequently in protectedareas in these regions (Brashares et al., ; Newmark,). Large, long-lived apex predators with low productivityand slowmaturation rates, such as large raptors, are especiallyvulnerable to increases in mortality rates, which can have asignificant impact on population viability (Sæther & Bakke,). Given such vulnerability, increasingly intense persecu-tion and hunting pressure related to commercial trade wassuggested as one of the major drivers of the widespread de-cline of vultures (i.e. Rüppell’s Gyps rueppellii, white-backedGyps africanus, lappet-facedTorgos tracheliotus, white-headed

R. BUIJ (Corresponding author) Alterra, Wageningen University and ResearchCentre, PO Box 47, 6700 AAWageningen, The NetherlandsE-mail ralph.buij@wur.nl

G. NIKOLAUS Feldweg 87, Cuxhaven, Germany

R. WHYTOCK School of Biological and Environmental Sciences, University ofStirling, UK

D. J. INGRAM School of Life Sciences, University of Sussex, Brighton, UK

D. OGADA* The Peregrine Fund, Boise, Idaho, USA

*Also at: National Museums of Kenya, Ornithology Section, Nairobi, Kenya

Received August . Revision requested December .Accepted April .

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Trigonoceps occipitalis, and hooded vultures Necrosyrtes mon-achus) in the savannah biome during – (Thiollay,, ; Rondeau & Thiollay, ). Although a varietyof techniques are used to kill vultures and other raptors fortraditional medicine and consumption (Buij & Croes, ),the use of poisoned baits is probably the most widespreadmethod, often killing many vultures in a single location(Mander et al., ; Saidu & Buij, ).

We evaluated the potential impact of the traditional medi-cine and commercial bushmeat trades on raptor populationsin West and Central Africa, based on counts of raptor car-casses offered for sale at market stands.We assessed the com-position of raptor carcasses offered for sale, and investigatedthe relationship between the numbers sold andmorphologic-al and ecological characteristics of the species identified. Ourresults were used to determine which species are most likelyto be vulnerable to the trade and in which regions and coun-tries. Based on previous studies we expected some taxa (e.g.vultures) and heavier-bodied species to be represented atmarkets more frequently than other species (Nikolaus, ;Williams et al., ).We also predicted that a species’migra-tory status would influence its trade numbers. Afro–Palearctic migrants spend –months of the year at northernlatitudes (with the exception of over-summering individualsof some species) and were expected to be represented lesscommonly than Afrotropical resident species (i.e. those thatare present year-round in the region), including intra-Africanmigrants. Controlling for species’ abundance, we expectedscavengers and savannah species to be recorded more fre-quently than non-scavengers and forest species, which are as-sumed to be harder to kill (i.e. poison) and detect,respectively. As vultures are known to be an important

component of traditional medicine in the region, we deter-mined the overall contribution of vultures to the total numberof raptor carcasses recorded, and examined temporal changestherein.We also evaluated changes in the proportion of blackkitesMilvus migrans among carcasses, because these relative-ly common raptors are used regularly as substitutes for vul-tures by fetish traders, who pluck feathers from the kites’heads so that they resemble hooded vultures (Nikolaus,). Vultures have become rare, and their partsmore expen-sive, and therefore we expected that the contribution of blackkites to carcass counts might have increased over the years.We estimated the numbers of raptors traded per annum, toassess the potential impact of the regional trade on threatenedpopulations.

Methods

Market inventories

Carcass counts were conducted at fetish and bushmeat mar-kets in the following countries throughoutWest and CentralAfrica (Fig. ): Benin, Burkina Faso, Cameroon, DemocraticRepublic of the Congo, Equatorial Guinea, Gabon, Ghana,Ivory Coast, Mali, Niger, Nigeria and Togo. These includedour own counts conducted at intervals of one year or moreduring – in eight West African countries and threeCentral African countries (Supplementary Table S). Ourdata were supplemented by published and unpublished re-ports of raptor carcasses recorded during surveys of bush-meat markets in Cameroon, Equatorial Guinea and Gabonduring –. The latter counts were gathered from the

FIG. 1 Locations of the markets in West and CentralAfrica where surveys of raptorcarcasses for sale wereconducted during –(Supplementary Table S).Biomes are based on White().

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bushmeat database of the OFFTAKE project (OFFTAKE,), a collaborative project that collates datasets thatquantify the offtake of terrestrial species (e.g. from subsist-ence hunting, medicinal use, trophy hunting). Datasets forthe OFFTAKE database were gathered by searching the lit-erature and contacting authors to request their raw data.Our surveys covered mostly fetish markets in West Africaand commercial bushmeat markets in Central Africa.Stands were visited throughout the year, covering the nor-thern winter and summer periods as well as the local dryand wet seasons (Supplementary Table S). Individualstands were surveyed only once per year. A proportion ofthe same stands were revisited in different years, althoughrelocation of stands and changes in ownership and standnumbers made it difficult to track individual standsthroughout the study period. For the same reason, the num-ber of stands visited each year varied (SupplementaryTable S). Countries with larger, more numerous wildlifemarkets (e.g. Benin, Nigeria) were visited more often andcovered more extensively than countries where the tradewas limited (e.g. Ghana, Togo). The markets surveyedwere in villages and towns distributed over a wide geograph-ical area and were approximately equally distributed amongforest (n = locations) and savannah, and forest–savannahtransition biomes (n = ; Fig. ), thus minimizing any site(i.e. habitat) effect on species composition of the overallsample. Some markets were visited more often than others,however, and the largest markets in Benin and Nigeria inparticular were located near or in the forest biome. Insome countries, such as Nigeria, only a proportion of well-known markets were visited, whereas most or all knownmarkets were visited in other West African countries.Local interpreters assisted in locating markets and checkingstalls. Carcasses were enumerated by observing and count-ing each raptor on display. Some birds were represented byentire carcasses, others merely by their heads; both are re-ferred to here as representing a carcass.

Trade per country and region

The proportion of hooded and palm-nut vulturesGypohieraxangolensis, large-bodied (i.e. . kg) Afrotropical vultures,black kites and other diurnal raptors among total carcasscounts was calculated, to evaluate differences between coun-tries (those with the largest markets: Nigeria, Benin) and re-gions (West and Central Africa). We treated palm-nut andhooded vultures separately because they are both known tobe commonly traded (Nikolaus, ); the first is a largely fru-givorous, not uncommon vulture of wet savannahs and for-ests, and the second is a locally common scavenger oflivestock carcasses, waste, faeces and other anthropogenicoffal in and around settlements. Large Afrotropical vultures(Rüppell’s, lappet-faced, white-backed, and white-headed

vultures) were considered separately because they are particu-larly highly valued by fetish traders and have undergone thegreatest declines in the region (Thiollay, ). Black kiteswere considered separately because they are among themost common raptors in the fetish trade and are known tobe sold as substitutes for vultures. We also evaluated changesin the proportional contribution of black kites and hooded,palm-nut and large Afrotropical vultures among cumulativecounts of raptor carcasses in all West African markets during–. Relative abundance of carcasses, rather than totalcounts, was evaluated because survey effort and recordedtrade volumes varied between years. We used standard linearregression to investigate whether the proportions of theseraptors in counts varied between years. As necessary, datawere log -transformed to meet the criteria of normalityand homogeneity of variance.

Characteristics of traded raptors

Covariate modelling was used to evaluate predictions thattotal carcass counts for each species (i.e. the cumulative num-ber of complete skins or heads counted) increased with spe-cies’ abundance and bodymass, and varied according tomainhabitat, scavenging behaviour, phylogenetic position and mi-gratory status. The abundance of each species was taken fromthe most authoritative field guide for western Africa, fromMauritania in the north-west to Congo in the south-east(i.e. overlapping with the study area and period of thestudy; Borrow & Demey, ). Species were categorized ac-cording to their abundance, as follows: scarce (encounteredonly irregularly, and infrequently to rarely within its normalhabitat), uncommon (encountered relatively frequently butnot regularly within its normal habitat), not uncommon (usu-ally, but not invariably, encountered within its normal habi-tat), common (or locally common; invariably encounteredsingly or in significant numbers within its normal habitat,sometimes only locally). Information on the main habitat(i.e. most commonly found (year-round): savannah, forestor both), migratory status and mean body mass was alsotaken from the literature (Del Hoyo et al., ; Borrow &Demey, ; Ferguson-Lees & Christie, ). Egyptian vul-tureNeophron percnopterus, peregrine falcon Falco peregrinusand common kestrel Falco tinnunculus have Afrotropical andPalearctic breeding ranges and were considered Afro–Palearctic migrants based on the breeding range of themajority of individuals in West Africa (Thiollay, ).Because black kites were mostly yellow-billed kites (i.e.the Afrotropical race aegyptius, which outnumbers thePalearctic race migrans in most of West and Central Africa,apart from in the far west), the species was considered anAfrotropical resident. Body mass was averaged for adultmales and females. With regard to scavenging behaviour,species were categorized based on available information

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on their diet composition in sub-SaharanAfrica (e.g. Brown&Amadon, ; Steyn, ; Mundy et al., ; Ferguson-Lees& Christie, ): non-scavenger (including species that scav-enge only rarely or occasionally), frequent scavenger (sca-venges frequently but also consumes a significantproportion of live prey; palm-nut and white-headed vultures,tawny eagle Aquila rapax, black kite, Eurasian marsh harrierCircus aeruginosus, bateleur Terathopius ecaudatus), and ob-ligate or near-obligate scavenger (Rüppell’s, lappet-faced,white-backed, hooded, Egyptian vultures). Unlike other OldWorld vultures the white-headed vulture was not categorizedas an obligate scavenger because it is likely to consume liveprey regularly (Murn, ). The Eurasian marsh harrier fre-quently scavenges in the European part of its winter range(e.g. Hiraldo et al., ) and this is also likely to be the casein the Sahel (Zwarts et al., ).We used results of phylogen-etic analyses based on nuclear and mitochondrial DNA toclassify raptor species into six groups (Lerner & Mindell,; Griffiths et al., ; Table ).

We used generalized linear models with a negative bino-mial distribution and log link function using the packageMASS in R v. ... (R Development Core Team, ) tomodel how explanatory variables describing the various spe-cies characteristics (Table ) affected total carcass counts perspecies, summed across all the data, including across yearsand across all sites. Habitat, functional group, phylogenyand status were included as categorical variables, abundanceas an ordinal variable and body mass as a continuous vari-able. We explored three sets of models, each consisting ofall possible subsets of combinations of explanatory variables,including one of three explanatory variables for functionalgroup (Table ). By including three subdivisions for the func-tional group variable in eachmodel set, we examined the rela-tive support for each of three alternative hypotheses: thatspecies carcass counts are best explained by () an increasingfrequency of scavenging, from non-scavenger, to frequent, to

obligate scavenger, () frequent scavenging (i.e. without dif-ferentiation between obligate and frequent scavengers), or() obligate scavenging. Support for the latter would indicatethat obligate scavenging drives carcass abundance patterns,whereas support for the second subdivision would suggestthat abundance patterns were driven by frequent scavenging.We used the corrected Akaike information criterion (AICc)value to select the most parsimonious models (those that fitthe data best with the fewest parameters; i.e. with the lowestAICc; Burnham & Anderson, ), and the top four ΔAICcof models as the cut-off criterion for delineating a set of topmodels. We computed model-averaged parameters by aver-aging over all models in the set of top models. We used thedredge function in R (part of the package MuMIn v. ..;Bartoń, ) to implement a model-averaging approach forthe top models to make robust parameter estimates and pre-dictions (Johnson & Omland, ), and estimated the rela-tive importance of each variable, based on the sum of Akaikeweights. We subsequently evaluated the effect of variablesbased on overlap of the % confidence intervals (followingBurnham & Anderson, ).

Total numbers involved in the trade

To determine the potential impact of the trade on raptor po-pulations, we estimated the number of raptors traded annu-ally at West African markets during –, usingextrapolation of mean counts per market stand andknown carcass turn-over rates. These estimates were basedon carcass counts at stands visited in , stands in, stands in , stands in , and stands in, in Benin, Nigeria, Mali and Burkina Faso. Because spe-cies composition varied between Nigeria and Benin we cal-culated mean counts per stand separately for these and theremaining countries, and extrapolated to the estimated totalnumber of stands. In Nigeria we visited approximately

TABLE 1 Explanatory variables used to examine the number of carcasses per species of raptors sold for fetish or bushmeat in markets inWest and Central Africa (Fig. ) during –.

Covariate Description

Abundance Common, not uncommon, uncommon, scarceHabitat Savannah, savannah & forest, forestFunctional group A Non-scavenger, frequent scavenger, obligate scavengerFunctional group B Non-scavenger, scavengerFunctional group C Obligate scavenger, otherMigratory status Afro–Palearctic migrant, Afrotropical residentBody mass Mean body mass (kg) of adultsPhylogeny GYPINA Old World vultures (Aegypius, Gyps, Necrosyrtes, Torgos, Trigonoceps); ACCIPITRINA

booted and hawk eagles, sparrowhawks, chanting goshawks, harriers, African fish eagle, black kite,buzzards, bat hawk (Aquila, Hieraaetus, Lophaetus, Polemaetus, Stephanoaetus, Accipiter, Melierax,Micronisus, Circus, Haliaeetus, Milvus, Buteo, Butastur, Kaupifalco, Macheiramphus); FALCONIDAEfalcons (Falco); GYPAETINI Pernine kites, gymnogene, Old World vultures (Aviceda, Pernis,Polyboroides, Gypaetus, Neophron); CIRCAETINA snake eagles (Circaetus, Dryotriorchis); OTHERelanine kites, secretary bird, osprey (Elanus, Chelictinia, Sagittarius, Pandion)

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one-third of the market stands trading in animal parts in, and therefore we tripled the number of stands to de-rive a country-wide estimate of stands. We estimated atotal of stands for Benin and for the remainingWestAfrican countries where surveys had been conducted. Wecautiously estimated the minimum and maximum numberstraded based on turnover rates of two to three birds perstand per year, although detailed examinations for variousspecies suggest that this turnover rate can be higher (–or more carcasses per year; Cocker, ; Nikolaus, ;Awoyemi, ; G. Nikolaus, unpubl. data).

Results

Trade per country and region

Black kite and hooded vulture together represented % of atotal , raptor carcasses of species recorded at marketsin West and Central Africa (Supplementary Table S).Shikra Accipiter badius was the most commonly traded smallraptor, comprising .% of the total carcass count. Afro–Palearctic migrants together represented .% of carcasscounts. This is assuming that short-toed Circaetus gallicusand Beaudouin’s snake eagle Circaetus beaudouini carcasseswere divided equally between species, and excluding the(likely) possibility that the Palearctic race migrans of blackkite comprised a small proportion of black kite carcasses.The most common Afro–Palearctic migrant among carcasseswas the Eurasian marsh harrier. Palm-nut and Rüppell’s werethe most commonly recorded vultures, after the hooded vul-ture. However, the contribution of vultures to total carcasscounts varied between countries and regions (Fig. ); whereasthe greatest proportion and diversity of large Afrotropical vul-tures (Rüppell’s, white-backed, white-headed, lappet-faced vul-tures) were recorded in Nigeria (%; n = carcasses),relatively few were offered for sale elsewhere in West Africa(.%; n = ,). In Central Africa palm-nut vulture carcasseswere recorded most commonly (% of total counts; n =

carcasses), contrary to the situation in West African countries(–% of carcasses). Overall, % of carcasses on offer were ofspecies categorized as threatened (Near Threatened toEndangered) on the IUCN Red List of Threatened Species(IUCN, ). Of these (n = ), % were found in Nigeriaand % in Benin. Nigeria was the only country where the re-gionally threatenedmartial eaglePolemaetus bellicosus and sec-retary bird Sagittarius serpentarius were recorded at markets(Supplementary Table S). Despite more than half of markets,including some of the largest markets, being located in the for-est biome, % of carcasses were of species mainly associatedwith savannah habitats, suggesting that raptors are transportedsignificant distances to commercial markets.

The data did not indicate a significant increase in the pro-portional contribution of black kites to total carcass counts

during – (linear regression: F, = .,β = . ± SE ., P = ., adjusted R = .). However, sur-veys in may not have yielded a representative sample be-cause a relatively small number of carcasses was recorded(n = ) compared to other years (n = –). Excluding from the analysis, a significant proportional increase ofblack kites over the years was apparent (linear regression:F, = ., β = . ± SE ., P = ., adjusted R = .;Fig. ), providing support for the idea that black kites havebeen traded increasingly since the late s. No significanttemporal trend was detected in the proportion of largeAfrotropical (F, = ., β =−. ± SE ., P = ., ad-justed R =−.), palm-nut (linear regression onlog -transformed data: F, = ., β =−. ± SE .,P = ., adjusted R =−.) or hooded vultures (F, = .,β =−. ± SE ., P = ., adjusted R =−.) amongraptor carcasses.

Characteristics of traded raptors

Our models found strong support for an influence of spe-cies’ abundance, habitat, migratory status, and scavengingbehaviour on carcass counts. All six plausible models (i.e.models with ΔAICc, of the top model; Table ) includedthe influence of species’ abundance and scavenging behav-iour, and five and four of the six top models featured habitatand migratory status, respectively. Body mass was repre-sented once in the top model set, and phylogeny and func-tional group C were not included. The four most importantpredictors among the six plausible models, in decreasingorder of importance, were species’ abundance (relative im-portance: ), habitat (.), functional group B (.), and

FIG. 2 Percentages of black kites Milvus migrans, largeAfrotropical vultures (Rüppell’s Gyps rueppellii, lappet-facedTorgos tracheliotos, white-backed Gyps africanus, andwhite-headed vultures Trigonoceps occipitalis), palm-nutGypohierax angolensis and hooded vultures Necrosyrtesmonachus, and other raptors among raptor carcasses recorded atmarkets in Nigeria (n = carcasses), Benin (n = ,), Mali,Togo, Niger, Ivory Coast, Ghana and Burkina Faso (n = ),and Cameroon, Equatorial Guinea, Gabon and DRC (n = )during –.

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status (.; Table ). The model-averaged parameters of thetop models (Table ) strongly supported the hypothesis thatmore common species were represented more often amongcarcasses than scarcer species. Forest species were less likelyto be found in markets than savannah species, or habitatgeneralists that inhabit both savannah and forests (Fig. ).Scavenging behaviour increased the probability of beingtraded compared to non-scavenging (Fig. ) but there waslittle support for the idea that obligate scavenging alonewas responsible for this pattern (functional group C fea-tured only twice among models with AICc weights $ %;Table ). Rather, our results strongly suggest that all speciesthat scavenge frequently (i.e. frequent and obligate scaven-gers) are traded more commonly than those that consumecarrion only rarely or occasionally (Table ). Species withan Afrotropical breeding range were more likely to be tradedcompared to those with a Palearctic breeding range (Fig. ).Although body mass featured in the top model set (relativeimportance: .; Table ), the confidence intervals of thebody mass predictor included zero, suggesting species’body mass did not influence carcass counts.

Total numbers involved in trade

In West Africa during – an estimated ,–,raptors were traded each year, based on extrapolated carcasscount data (Supplementary Table S). An estimated –, raptors were traded each year in Benin, ,–,in Nigeria, and – in the rest of West Africa(Supplementary Table S). The bulk of the trade was inNigeria (% of carcasses), with % in Benin and % else-where in West Africa. Assuming turn-over rates of – indi-viduals per stand per year, an estimated ,–, hoodedvultures and ,–, black kites were traded during the-year period inWest Africa. Estimates for other commonlytraded large raptors during this period were ,–,palm-nut vultures, ,–, Rüppell’s vultures,

–, white-backed vultures, –, lappet-facedvultures, and – crowned eagles Stephanoaetus coro-natus. For –% of species (n = ) , individualsare estimated to be traded annually in West Africa.

Discussion

The diversity of raptor species, and number of individuals,offered at West and Central African markets, particularly inNigeria and Benin, is considerable. Approximately % ofthe region’s diurnal raptor species were on sale, suggestingthat many raptors are used as fetish species (Nikolaus, ,; Williams et al., ) as well as bushmeat (Saidu & Buij,; Buij & Croes, ; Whytock et al., ).

Our results indicate that Nigeria and Benin are import-ant drivers of the regional trade in raptors in West Africa.This supports an earlier assertion by Nikolaus () thatthere is a high per capita use of raptors for fetish inNigeria and Benin. Fetish demand and prices of vulturesare particularly high in Nigeria (Nikolaus, ), wherelarge Afrotropical vultures constituted a greater proportionof raptors traded compared to Benin or elsewhere in Westand Central Africa. Large Afrotropical vultures were alreadylargely extirpated in Nigeria in the early s (Nikolaus,), and human-commensal hooded vultures have de-clined (Ogada & Buij, ). The diversity and number ofvultures for sale in Nigeria support anecdotal evidenceand results of questionnaire surveys indicating that thecatchment area for Nigerian traders extends at least fromBurkina Faso to Chad (Nikolaus, ; Saidu & Buij, ).Because large Afrotropical vultures or their eggs are valuedat several months’ salary, Nigerian poachers invest in ob-taining them, sourcing them from countries in the wider re-gion (Saidu & Buij, ). Shifts in pressure to other species,such as migratory black kites, suggest that the trade has thepotential to affect raptor populations beyond West andCentral Africa.

For manyWest and Central African raptors the impact ofthe trade may be limited compared to other anthropogenicand climate-related factors that influence their food re-sources, nest availability, and population dynamics (e.g.Buij et al., a,b). The commercial trade, however, can beimplicated in the decline of vultures and other large raptorsin the region. For some species, such as Rüppell’s, hooded,white-backed, white-headed, and lappet-faced vultures, thenumbers traded probably represent a significant proportionof their regional populations. Although rigorous populationestimates are unavailable for most species, the extrapolatedannual toll of lappet-faced vultures in West Africa during– represents as much as .–.% of c. , indivi-duals estimated to have occurred in West Africa and theSahara during the s (Shimelis et al., ), assumingthey were all sourced from this region. However, trade

FIG. 3 Linear regression model of the relationship between thepercentage of black kites among raptor carcasses at markets inWest and Central Africa (Fig. ) and year of survey, during–.

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volumes may have constituted a higher proportion of popu-lations remaining in –, as was the case for the white-headed vulture. There were an estimated , or morewhite-headed vultures in West Africa in the s (Mundyet al., ), and .–.% of this number were channelledthrough the trade each year during –. As the mostrecent estimate suggests that as few as remained in

(C. Murn, unpubl. data), the annual trade constituted .–%of the remaining West African population. Hooded vultures,which are under pressure from poachers, were estimated tonumber c. , individuals in West Africa (Ogada &Buij, ). Our estimates suggest that .–% of those werelost to the trade annually during –. Our estimatesof annual tolls, even those based on more recent populationestimates, are likely to be biased low because we used conser-vative estimates of turnover rates to estimate numbers traded;other studies suggest these may be significantly higher (e.g.Awoyemi, ). Although we lack quantitative data, the ma-jority of raptors recorded at markets appeared to be adults,which have a vital role in population dynamics, especiallyfor larger species (Sæther & Bakke, ). Persecution maybe one of themost important factors of non-natural mortalityin threatened populations of large raptors, which may decline

even with only a small decrease in adult survival rates(Whitfield et al., ; Oro et al., ; Ortega et al., ).Assuming the majority of vultures and other large raptors onoffer at markets were killed specifically for trade, the tradeprobably contributed to increased mortality rates and signifi-cant population declines, including the % decline of largevultures outside protected areas in centralWest Africa during– (Thiollay, ).

The percentage of vultures among raptor carcasses washighest in Central Africa, mostly accounted for by palm-nutvultures. The palm-nut vulture is an important and valuablespecies for fetish purposes in West Africa, and individualshave been sold for c. USD in Nigeria (Nikolaus, ).We estimated its offtake in West Africa to be – indi-viduals per annum (i.e. .% of the continental populationof c. ,, most of which are in West and Central Africa;Mundy et al., ). However, the true impact of huntingon palm-nut vulture populations may remain largely con-cealed, at least in Central Africa, where the vultures areoften consumed in bushmeat hunting camps rather thanbeing transported to markets (Whytock et al., ).Although this highly prized species is categorized as LeastConcern on the IUCN Red List (IUCN, ) because of

TABLE 2 Top generalized linear models (Akaike weight. %) examining the relationship between cumulative carcass counts of raptorspecies (Supplementary Table S; n = , carcasses) at markets in countries in West and Central Africa during – (Fig. ) andthe species’ abundance, habitat, functional group, phylogenetic position, body mass, and migratory status (Table ), with degrees of free-dom, corrected Akaike information criterion (AICc), ΔAICc and Akaike weight.

Model1 df AICc ΔAICc Akaike weight2

Abundance + habitat + functional group B + status 9 434.51 0.00 0.31Abundance + habitat + functional group B 8 435.91 1.39 0.15Abundance + functional group B + status 7 437.32 2.81 0.08Abundance + habitat + functional group A + status 10 437.39 2.88 0.07Abundance + habitat + functional group B + body mass + status 10 437.45 2.94 0.07Abundance + habitat + functional group A 9 438.22 3.70 0.05Abundance + habitat + functional group B + body mass 9 438.78 4.27 0.04Abundance + functional group B + body mass + status 8 439.29 4.78 0.03Abundance + functional group B 6 439.79 5.27 0.02Abundance + habitat + functional group A + body mass + status 11 439.88 5.37 0.02Abundance + functional group A + status 8 440.11 5.60 0.02Abundance + habitat + functional group C + status 9 440.16 5.64 0.02Abundance + habitat + functional group C 8 440.28 5.76 0.02Abundance + habitat + functional group B + status + phylogeny 14 441.12 6.61 0.01Abundance + habitat + functional group A + body mass 10 441.17 6.65 0.01Abundance + habitat + functional group B + phylogeny 13 441.23 6.72 0.01Abundance + functional group A + body mass + status 9 441.33 6.81 0.01Abundance + habitat + body mass 8 442.00 7.49 0.01Abundance + functional group A 7 442.33 7.82 0.01Abundance + functional group B + body mass 7 442.36 7.84 0.01Abundance + habitat + body mass + status 9 442.48 7.97 0.01Abundance + habitat + status 8 442.68 8.17 0.01Null 2 497.20 62.69 0.00

Listed in order of most to least parsimonious model, after fitting combinations of all possible subsets with each of the three explanatory variables for func-tional group.The weight of evidence in support of the model (cf. Burnham & Anderson, )

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its large range, population size and apparently stable popu-lation, ongoing persecution warrants closer examination ofits population trends.

Other large raptors vulnerable to persecution includeAfrica’s largest eagles (martial and crowned). Extrapolationof the estimated annual toll suggests at least crowned ea-gles were traded commercially in West Africa during –, which represents an unknown but probably significantproportion of regional populations. Although these uncom-mon raptors are unlikely to be poisoned on a scale compar-able to scavengers, they may be shot; crowned eagles may belured by bushmeat hunters imitating the calls of prey animals(Whytock&Morgan, ). This may occurmore frequentlythan previously thought, as crowned eagles were the secondmost common forest species and the commonest large rap-tors (i.e. . kg) recorded at markets after Rüppell’s, white-backed and lappet-faced vultures. Their slowmaturation rateand biennial reproduction in tropical forests make thecrowned eagle one of the most vulnerable raptors to directpersecution (Shultz, ; Whitfield et al., ), com-pounding negative impacts of habitat loss and degradation,disturbance of nest sites, and prey depletion by bushmeathunters (Lindsey et al., ; Whytock et al., ).

The positive relationship between species’ abundance andcarcass counts suggests that at a regional scale species are tar-geted indiscriminately to supply the trade. However, our re-sults showed that Afrotropical habitat generalists inhabitingforests and savannahs, and those of savannah habitats, are

particularly commonly traded, whereas trade in forest spe-cialists is comparatively uncommon. This relative scarcityof forest-restricted species in the trade may be related tothe difficulty in finding, shooting or poisoning these species,which are generally more elusive. The greater numbers ofAfrotropical residents in the trade, including intra-Africanmigrants, is probably related to their year-round availability;the majority of Afro–Palearctic migrants spend much of theyear outside the poachers’ catchment area.

Our models support the hypothesis that, together withobligate scavenging vultures, raptors that scavenge frequent-ly are more likely to end up at markets compared to non-scavenging species. We suspect this is related to the easeof killing most scavengers using poisoned baits, which isprobably the most widespread method used to kill raptorsand other predator populations in sub-Saharan Africa(Ogada, ). Frequent use of human-dominated, low-quality habitats may increase the vulnerability to poisoningof some obligate and frequent scavengers (black kite,hooded vulture; Otieno et al., ; Kendall, ; Buijet al., a). Some frequent scavengers (black kite,Eurasian marsh harrier) congregate at easily detectableroosts, possibly increasing their vulnerability to poachers;the high search efficiency of others (bateleur, tawny eagle;Kendall, ; Kane et al., ) may facilitate poisoningor trapping using baits. Alternatively, some frequent scaven-gers may constitute bycatch of poachers targeting morehighly prized vultures.

TABLE 3 Effects of species characteristics assumed to influence cumulative carcass counts of raptor species (n = , carcasses) at mar-kets in countries in West and Central Africa during – (Fig. ), with model-averaged parameter estimates for each variable(Table ) in the six most strongly supported models (Table ), and the relative importance of explanatory variables.

Variable Parameter estimate (95% CI) Relative importance1

(Intercept) 3.59 (2.38–4.81)Abundance2

Not uncommon −1.35 (−2.11 –−0.60) 1.00Uncommon −2.53 (−3.22 –−1.84)Scarce −3.50 (−4.69 –−2.31)

Habitat3

Savannah 0.97 (0.21–1.73) 0.90Savannah & forest 1.46 (0.59–2.32)

Functional group B4

Scavenger 0.95 (0.38–1.52) 0.83Status5

Afrotropical resident 0.66 (0.07–1.25) 0.72Functional group A4

Frequent scavenger 0.80 (0.11–1.50) 0.17Obligate scavenger 1.08 (0.32–1.84)

Body mass −0.03 (−0.19–0.13) 0.10

Calculated by summing Akaike weights across the top model set (Burnham & Anderson, ); % confidence intervals of the estimate not overlappingzero are indicated in bold.Reference group: commonReference group: forestReference group: non-scavengerReference group: Afro–Palearctic migrant

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It is possible that not all raptors recorded at marketswere killed for trade; casualties related to other anthropo-genic factors (e.g. electric power lines, roads, pesticides), ordisease may also be sold in markets. However, indirectevidence suggests that mortalities related to these factorsprobably account for only a small proportion of raptors of-fered at markets. The electrical power transmission systemover most areas in West and Central Africa is poorly de-veloped, unlike in North and southern Africa, where this isa significant cause of mortality (Nikolaus, ; Jenkinset al., ). There are unlikely to be many raptor deathscaused by road traffic given the condition of most roadsprevents driving at high speed, which is confirmed bygenerally few raptor carcasses found along roads (R. Buij,pers. obs.). Casualties from secondary pesticide poisoningalso appear to be generally low, being significant onlywhen colonies of red-billed quelea Quelea quelea aresprayed with fenthion when irruptions occur (Keith &Bruggers, ). Deaths of hooded vultures as a result ofavian influenza may be significant, at least locally asshown in Burkina Faso (Ducatez et al., ), but we arenot aware of similar die-offs elsewhere in the region. We

therefore assume that the majority of raptors on offer atmarkets are probably killed deliberately for the trade,which is supported by information obtained from tradersin Nigeria (Saidu & Buij, ).

The trade in raptors for traditional medicine or for food islikely to have contributed considerably to the significant de-cline of vultures and other large raptors, and possibly also to anumber of smaller raptors, in West and Central Africa.WithinWest Africa, Benin andNigeria collectively accountedfor % of the carcasses traded during –.Conservation efforts focused on these two countries wouldtherefore have the most significant impact on curtailing thistrade within the wider region. More than a quarter of raptorssold at the markets surveyed inWest and Central Africa since are categorized as threatened on the IUCN Red List(IUCN, ), including five Afrotropical vultures that war-rant uplisting to Critically Endangered on the basis of popu-lation decline (Ogada et al., ). A lack of population datamakes it difficult to conduct accurate Red List assessments forsome vulnerable species that are commonly exploited by thetrade (palm-nut vulture, crowned eagle). Increasing prices areleading to increasing pressure on remaining vultures, as

FIG. 4 Plots of the modeled relationship between carcass counts of raptor species and the species’ (a) abundance, (b) habitat, (c)functional group B, and (d) status (Table ), as estimated by the top model (cf. Table ). Carcass counts are plotted on their originalscale. The black horizontal line represents the model-predicted value, with all other variables set to their most common category, andthe shaded areas indicate % confidence bands; the vertical ticks indicate number of observations.

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well as on species sold as vultures to unsuspecting consumers,notably black kites. The number of threatened species dis-played openly in markets suggests that their declining popu-lation status is unknown or of little concern to those whoenforce wildlife legislation, or those involved in the trade.In some countries efforts are made to enforce conservationlegislation but a combination of corruption, lack of fundingand lack of reliable information at various levels within gov-ernment departments results in de facto impunity for traders.In other countries, such as Benin, the government supportsthe trade as part of the country’s cultural heritage. There isa need for international action targeting suppliers, tradersand consumers, initially focused on large markets inNigeria and Benin, and for stronger commitments from gov-ernments to halt the trade in threatened raptors.

Acknowledgements

We thank two anonymous referees for their constructivecomments. Unpublished data were provided by theUniversity of Stirling African Forest Ecology Group,which works in Gabon under agreement with the Instituteof Tropical Ecology Research.

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Biographical sketches

RALPH BU I J studies relationships between land-use change, hunting,and protected areamanagement and population dynamics of birds andmammals in West and Central Africa. GERHARD NIKOLAUS is an or-nithologist with many decades of experience in sub-Saharan Africa,and the author of Distribution Atlas of Sudan’s Birds, with Notes onHabitat and Status. He performed most of the market surveyspresented here. ROB IN WHYTOCK ’s research interests include inves-tigating the decline of Afro–Palearctic migrants, and the conservationecology of birds in the Lower and Upper Guinean forests. DAN I E L

INGRAM is a conservation scientist and modeller investigating the ex-ploitation of terrestrial species throughout the tropics. He is the man-ager of the OFFTAKE database. DARCY OGADA is a conservationbiologist whose main focus is East African raptors and combating poi-soning of wildlife.

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