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Wing, tail and bill lengths of Hooded Vultures were measured on 36 wild-caught birds and 75 in museum collections. A further 60 measurements were taken from literature, and 40 measurements were received from the Musée royal de l’Afrique centrale (Tervuren, Belgium). By grouping them into regions of Africa it was shown that the smallest birds were in West Africa and the largest in southern Africa (which is well known), with a gradation in between. Sizes varied according to a cline, and were correlated with average altitude. Given that the species has the same colouration (head, caruncles, plumage) from one end of the range to the other, indeed that populations are contiguous from Senegal to South Africa, then this goes against recognising any subspecies, but rather an intraspecific trend in sizes

Groups of the Hooded Vulture Necrosyrtes monachus were observed pick feeding at small piles of boiled and crushed African Oil Palm Elaeis guineensis fruit at the south Gambian village of Marakissa (16.39044°N, 13.12055°W) on several occasions in the 1980s and 1990s. The vultures foraged alongside working women farmers (Barlow et al 1997). This remains the only published reference for this type of feeding habit based on direct observations. The utilisation of non-human harvested African Oil Palm E. guineensis fruit (also known as palm-nuts) as a food source by N. monachus has been described previously, derived from a road-killed bird collected on 22nd September 2003 in coastal Gambia that was found with a stomach containing 11 fresh whole fruits of E. guineensis (Barlow 2004). The intact fruits had not been boiled, crushed or seemingly processed by farmers in the small-scale village enterprise palm oil production process. Another complete N. monachus specimen found in a rice field 100 km inland on 9th February 2002 had five Oil Palm pits (all the fleshy mescocarp parts were missing and the seed is contained inside the pit, e.g. see Figure 3) in the desiccated remains (Barlow 2004). We have no reports from elsewhere of N. monachus feeding on Oil Palm fruit or the by-product since the 2004 report, and a photographic record of N. monachus foraging on Oil Palm fruit in the field remains sought after. In the context of other species, feeding on palm fruit by the Palm-nut Vulture Gypohierax angolensis is well documented (Bannerman 1930, Clark & Davies 2018), and three fruits were found in the stomach of a desiccated carcass of an adult African Harrier-Hawk Polyboirodes typus found in the Central River Region of Gambia, February 2005 (personal observation).

We present biometrical data assembled from a combined total of 37 complete and partially cleaned skulls and feathered heads for the two putative subspecies of Hooded Vulture Necrosyrtes monachus monachus and N. m. pileatus (which Mundy et al. (1992) credibly argue should be N. m. carunculatus). We report on mostly insignificant variation in measurements taken from across three regions of the Hooded Vulture range. For N. m. pileatus (n = 22) the measurements are assembled from 13 live birds captured, tagged and released in Botswana between 2014-2017, seven museum specimens held in The National Museums of Kenya collected during 1913-1950, and two as described below. We compare with N. m. monachus (n = 14) where we measured eight specimens produced by road traffic accidents in The Gambia 2002-2019 of which seven are cleaned bare skulls and one a feathered study skin. We also measured six feathered heads and three skulls from several different countries in Africa, collected during 1832-1929 (n = 6 monachus, 2 pileatus, and 1 unknown) and held at the Natural History Museum, Tring, UK. Cranial materials for Hooded Vulture are scarce in world museums and the Gambian sample consisting of seven cleaned skulls represents the largest known number for a single country. Different populations across the regions vary considerably in both feeding habits and home ranges. We hypothesised that different foraging ecologies may have led to adaptation in bill morphology. Presented here for the first time are a series of skull morphometrics which test for variation in cranial biometrics and bill morphology from across the range of the Hooded Vulture. The Gambian bird has been DNA sequenced and a planned genetics study of other populations will resolve the long-standing taxonomic debate.

The head−neck system of birds is a highly complex structure that performs a variety of demanding and competing tasks. Morphofunctional adaptations to feeding specializations have previously been identified in the head and neck, but performance is also influenced by other factors such as its phylogenetic history. In order to minimize the effects of this factor, we here analyzed the anatomy of three closely related vultures that distinctly differ in feeding strategy. Vultures, as obligate scavengers, have occupied a special ecological niche by exclusively feeding on carrion. However, competition among sympatric vultures led to ecological differences such as preference of certain types of food from a carcass. Via comparative dissections we systematically described the craniocervical anatomy in the Griffon vulture (Gyps fulvus), the Cinereous vulture (Aegypius monachus) and the Hooded vulture (Necrosyrtes monachus) that exploit the same food resources in different ways. Our results revealed differences in the number of cervical vertebrae, in the morphology of the atlas−axis complex as well as in the neck musculature despite overall similarities in the musculoskeletal system. Gulpers, rippers and scrappers adopt specific postures while feeding from a carcass, but the cervical vertebral column is indispensable to position the head during all kinds of behavior. The great range of demands may explain the conservation of the overall muscle topography of the neck across the studied taxa.

SummaryUnderstanding the attitude of people towards vultures, especially factors that influence behaviours that support their conservation, is crucial if the decline in vultures is to be slowed and reversed. Their vital ecosystem function in keeping the environment free of carcasses and reducing the spread of disease is not yet appreciated in Ghana. Little is known about the attitude of Ghanaians’ about vultures. Structured questionnaires and key informant surveys were employed with a sample size of 460 respondents randomly selected across Ghana. Over 85% of respondents were familiar with the Hooded Vulture Necrosyrtes monachus and vultures were culturally important to 56% of respondents. Diseases that affect livestock are claimed to be treated with chemicals such as diclofenac sodium to which vultures are highly susceptible globally and livestock carcasses were not available to vultures as 53% of respondents bury carcasses. A new poisoning pathway has emerged in which furadan is used to poison wildlife for bushmeat and the offal removed which is then consumed by vultures, as indicated by 78% of respondents. The majority of respondents positively thought vultures were important and must be protected. Poisoning, habitat loss particularly the loss of silk cotton tree Ceiba pentandra and trade in vulture parts for traditional medicine are major threats to vultures in Ghana. Continuous awareness creation, positive attitude towards the environment, vulture conservation programmes and protection of breeding sites were some urgent conservation actions recommended to ensure the survival of vultures.

The hooded vulture Necrosyrtes monachus is a critically endangered species and recently published evidence suggests that its population is experiencing an extremely rapid decline, owing to indiscriminate poisoning, trade for traditional medicine, hunting, persecution, electrocution, habitat loss and degradation. As a result of these threats, the species is gradually disappearing from its range and thus, the sighting of vultures or their nests is becoming very rare. This paper thus, presents a report on the sighting of the Hooded Vulture and its nest at Emi Abumo Woro Village, Kogi State, Nigeria. This is an evident and equally an indication that Emi Abumo Woro village harbours the remnant of this rare and critically endangered bird species. Materials and Methods: Two vultures and a nest were sighted on 3rd March, 2018, during a bird survey of the area. The nest was sighted on a Baobab tree Adansonia digitata, located in a fork on the main trunk, at a height above ground of 12.8 m. The nest was accessed using a ladder to determine its content. Results: The content of the nest were two eggs, which were photographed. On 17th March, 2018, when the nest was revisited, one of the eggs had disappeared and could not be accounted for. Fifteen other vultures were seen flying within the nest environment. The nest was revisited on 2nd April, 2018 and it was observed that the one remaining egg had been hatched and the vultures had disappeared to an unknown destination. The nest was a statant-cupped shaped nest of large size and the nest materials were mostly sticks and leaves of the nesting tree, which were used in lining the nest. Conclusion: This study reveals that the Hooded Vulture still exist in some parts of Nigeria and that Emi Abumo Woro village presents a good breeding site for this vulture. It is therefore very important to take some measures towards conserving the vulture and its breeding site.

Background and objective: African vultures are under pressure from various, well-known anthropogenic threats. Here we describe and aim to highlight a littleknown source of mortality to two Critically Endangered vulture species (Gyps africanus and Necrosyrtes monachus), as well as the Endangered Cape Vulture (Gyps copropheres) in southern Africa – that of captive big cats killing vultures that land in their enclosures to feed on food scraps or faeces or to bathe in drinking water. Methods: Personal observations, reports from public, interviews with current and former staff from predator parks and lion hunting ranches. Discussion: While the spatial and numerical extent of this mortality has not yet been quantified, if it is found to be widespread then failure to address it may present a risk to the regions’ vulture populations. Conclusion: We encourage captive breeding facilities and regulatory authorities to take appropriate action to prevent free-roaming vultures from coming into contact with captive big cats, and we highlight the need for further research to determine the spatial extent and magnitude of this threat to African vultures.

Hooded Vulture Necrosyrtes monachus populations have declined dramatically in recent years, but we know little about their ecology. We radio-tagged four vultures in northern Botswana to gather data on animal movement and home-range patterns. Hooded Vultures were primarily sedentary at night. Hooded Vultures moved similar distances and speeds during the wet and dry season, and travelled over similar home ranges as measured using minimum convex polygons (MCP), but used much smaller core areas during the dry (breeding) season. We found significant differences in mean distances and speeds moved among different birds, and when comparing day to night, but not between the wet (non-breeding) and dry (breeding) season or by year. All of the variables we tested, including individual vulture differences, season, year and number of fixes, significantly influenced 95% MCP and kernel density estimate (KDE) home-range sizes. Hooded Vultures used significantly smaller KDE home-range sizes during the dry (breeding season) than in the wet (non-breeding) season. Hooded Vultures travelled smaller daily distances over smaller home ranges than most other vulture species for which data exist.Keywords: Botswana, kernel density estimate, minimum convex polygon, raptor

Avian scavengers, by feeding on carrion and other organic matter, provide critical ecosystem services. Vultures, the only obligate avian scavengers, have reportedly experienced massive population declines in Africa yet current knowledge regarding their status in most West African countries is unknown. This study set out to ascertain the status of the avian scavenger community in Edo State, southern Nigeria. We made total counts of all scavenging birds at foraging and roosting sites in 13 urban areas. We recorded three species of avian scavenger which were, in order of decreasing relative abundance, Pied Crow Corvus albus, Yellow-billed Kite Milvus migrans and Hooded Vulture Necrosyrtes monachus. There was a positive correlation between relative abundance of avian scavengers and human population size, such that more populous urban centres had larger populations of scavengers. We counted more scavenging birds at roosting sites than at foraging sites. While the Pied Crow and Yellow-billed Kite appear to be thriving in Edo State, the Hooded Vulture appears to have experienced a massive population decline. Our results suggest that without immediate conservation effort such as protection, education and advocacy, the Hooded Vulture will be extirpated from this region in the near future. We suggest that these conservation efforts be focused on the largest urban areas. Furthermore, we recommend that other states in southern Nigeria be urgently surveyed in order for more general conclusions to be drawn about the fate of avian scavengers in this region.

Hooded Vultures Necrosyrtes monachus are critically endangered but little is known of their year-round use of nests or whether other species usurp Hooded Vulture nest sites. We investigated visitation rates by Hooded Vultures and other species (including potential nest predators and usurpers) to examine their effect on Hooded Vulture breeding success. We present observations of 33 species recorded by camera traps at 12 Hooded Vulture nests over a total of 93 nest-months (2 095 nest-days). Several pairs of Hooded Vultures visited their nests regularly during the non-breeding season, some adding nesting material, highlighting that pairs visited their nest(s) year round. Egyptian Geese Alopochen aegyptiaca, potential usurpers of raptor nests, were present at occupied and unoccupied Hooded Vulture nests, but we recorded no usurpation of nests by Egyptian Geese and they had no impact on vulture breeding success. Hooded Vulture breeding failure was linked to two species only: camera-trap imagery recorded one ca...

Relatively little is documented about nest material theft in vultures. We used camera traps to monitor Hooded Vulture Necrosyrtes monachus nests for a year. We report camera trap photographs of a starling Lamprotornis sp. removing what appeared to be dung from an inactive Hooded Vulture nest on Cleveland Game Reserve, north-eastern South Africa, in October 2016. We also had evidence of a Hooded Vulture attempting to remove twigs from the same nest in August 2016. This behaviour is previously unrecorded in Hooded Vultures and, although seemingly rare, it represents an attempt to reduce the energetic costs of nest building in this species.

Egyptian geese Alopochen aegyptiaca are widely reported to be territorial and aggressive. They are known to attack and sometimes kill other birds and they may attempt to usurp their nests. Here information is collated on the bird species whose nests have been used or usurped by Egyptian geese. Also presented are observations from a series of camera trap images of an Egyptian goose laying eggs and incubating in a hooded vulture Necrosyrtes monachus nest to which a juvenile hooded vulture returned repeatedly for food. Ten aggressive encounters were recorded between the Egyptian goose and the hooded vultures; the goose prevailed in five of these encounters, the vultures in four and on one occasion both vultures and goose fled the nest. This is the first time that an Egyptian goose has been recorded breeding in a hooded vulture nest. The hooded vulture chick successfully fledged and although the goose incubated for at least 20 days, for reasons unknown, its breeding attempt ultimately failed.Keywords: Alopochen aegyptiaca, camera trap, interspecies aggression, Necrosyrtes monachus, nest competition, usurpation

During the last decades, the critically endangered Hooded Vulture Necrosyrtes monachus has strongly declined across its African range. Although direct persecution has been suggested as a major cause of this decline, little is known about the impact of humans on reproductive output in West Africa. We studied the impact of human activities on the reproductive output of Hooded Vultures in the Garango area of Burkina Faso. Twenty and 56 nesting attempts were monitored, respectively, during the breeding season in 2013/14 and 2014/15, to determine reproductive success and identify causes of nest failure. Annual breeding success varied between 0.68 and 0.71 chicks fledged per breeding pair per year and productivity was assessed at 0.57 chicks fledged per territorial pair in 2014/15. The main threats imposed by humans were poaching of eggs, chicks and collection of nest materials, leading to 20% (13 out of 64 breeding attempts) of nest failures over the two years. An additional important reason for nest failure was the pruning and (partial) cutting of nest trees. Despite this high level of human interference, we found that Hooded Vulture nest success increased with proximity to human settlements, probably because breeding vultures benefit from protection by people against persecution and disturbance.Keywords: Burkina Faso, conservation, Hooded Vulture, human impact, reproduction

A number of vulture species were ubiquitous in undisturbed West African savannahs. However, in recent decades most species have declined rapidly and some are now at the brink of extinction. For some species, large protected areas are their last strongholds, but even there pronounced declines have become obvious in recent years. However, we lack even basic knowledge about current distribution, densities, movement patterns and threats. Comoe National Park (CNP) in northeast Cote d’Ivoire is one of the largest protected savannahs in West Africa and still hosts breeding populations of three critically endangered species (Hooded Vulture Necrosyrtes monachus, White-backed Vulture Gyps africanus, White-headed Vulture Trigonoceps occipitalis). In total, 590 km of searches for vultures and their nests were conducted on foot in southwest CNP in the dry seasons of 2018 and 2019. Thirty-seven active vulture nests (Hooded Vulture – 2, White-backed Vulture – 32, White-headed Vulture – 3) were discovered. CNP may be one of the last refuges for these species in Cote d’Ivoire and important for their conservation in West Africa. There are, however, hints that vultures have declined in CNP since the 1990s and are now rarer especially at the Park's fringe. Together with observations of increasing poaching activities, this underlines that large reserves with strict law-enforcement are needed to save West Africa's vultures from extinction.

We report findings on the vulture trade in northern Nigeria, where it is commonly practised especially to supply the traditional medicine industry. We administered an open-ended questionnaire to 113 traditional, predominantly Hausa medicinal traders in 39 markets within eight states in northern Nigeria. Of the interviewed traders, 78% only had feathers of vultures on display in their stalls, 11% also offered vulture heads and 4.4% offered entire vultures; 40% of traders sold vultures for spiritual healing and 25% sold vultures for consumption. Forty-three percent of traders were supplied most often from vulture populations inside Nigeria and 48% were principally supplied from other countries in the region, as far west as Benin and east to Sudan. Increased prices for parts during the past 10 years reflected similar, or perhaps increasing, demand but lower availability of vultures. Hooded Vulture ( Necrosyrtes monachus ) was the commonest species traded with 90% of parts belonging to this species. Vultures sold in stalls had been killed using agricultural chemicals, shotguns, traps, and ground tobacco powder. Urgent and drastic conservation measures are needed to prevent further exploitation of critically endangered vultures in Nigeria and surrounding countries. Keywords: traditional medicine, vulture trade, northern Nigeria, conservation

Vultures constitute an important functional group in many ecosystems, providing crucial ecosystem services both in natural and humanized environments. These scavengers are facing massive declines worldwide, but in several African countries virtually nothing is known on populations' status and threats, hampering the development of adequate conservation strategies. In Guinea-Bissau, globally important populations of Hooded Necrosyrtes monachus and African white-backed vultures Gyps africanus were recently reported. Using the country as a study area, we aim to characterize human-vulture interactions in West Africa applying a multidisciplinary approach. We assessed the status and distribution of vulture populations using data from 1711 km of roadside transects, examined predictors of their distribution, and produced a nationwide population estimate for the Hooded Vulture, using an innovative method based on the relationship between the size of human population in settlements and vulture numbers. We conducted 47 stakeholder interviews to assess perceived roles played by vultures, and to investigate potential anthropogenic threats. Hooded vultures were strongly associated with high human population densities, whereas no relation was found between African white-backed and Rüppell's vultures and any of the tested predictors, which included cattle density, precipitation and Normalized Difference Vegetation Index, among others. We estimate a national population of 43347 Hooded vultures, the largest population reported in the species range. Respondents were generally aware of the services provided by vultures, especially waste and carcass removal, including in urban areas. Hunting for witchcraft and traditional medicine was the most frequently recognised threat, while poisoning was ranked as having the highest impact. We hypothesise that poisoning-related mortality may be affecting African white-backed and Rüppell's vultures' distribution and explain their scarcity in apparently highly suitable habitats. Our results suggest a mutualistic rather than a commensalistic relationship between vultures and humans, with important implications for designing and implementing conservation strategies. Fundação para a Ciência e a Tecnologia (FCT); Institute of Biodiversity and Protected Areas of Guinea-Bissau-IBAP; Rufford Foundation; Fondation MAVA info:eu-repo/semantics/publishedVersion

Waste disposal sites are predominantly used as feeding sites for generalist birds. The main objective of this study was to assess the diversity and abundance of birds from three waste disposal sites in and around Gubre sub city, Guraghe zone in 2017. Data were collected using point count techniques from 6:00−10:00 a.m. in the morning and 4:00−6:00 p.m. in the afternoon for three consecutive days each in three study sites. During this study, a total of 2566 birds belonging to 17 species, 7 Families and 6 Orders were recorded. From the 17 identified species of birds, 11 species each were from site I and III, while the remaining 7 species were recorded from site II. Among the seven identified families, Accipitridae was numerically the dominant family represented with 7 species, while Columbidae and Scopidae were the least dominant families represented with 1 species each. At species level, Hooded vulture (Necrosyrtes manachus) was the most abundant bird species. The total abundance of birds was significant (ANOVA result, p=0.00) difference among the three sites. In general, highest number of individual birds were counted in site I (1210) followed by site III (974) and site II (382). A significant difference in the abundance of birds between morning and afternoon was also observed (t- test, p=0.044). Greater numbers of birds were counted in morning in all study sites (range: 93 in site II and 651 in site I). Site I was found to be with relatively higher value of species diversity (H’=1.2) than Site III (H’=1.01) and Site II (H’=0.90). In the study area, waste collectors, domestic dogs, cats and vehicles were considered as threats for waste dependent birds. More studies are required to make a complete list of available bird species in the study area.

As in many West African cities, in Dakar Hooded Vultures Necrosyrtes monachus have always been characteristic urban scavengers. The recent decline of Hooded Vultures in other parts of Africa, mainly eastern Africa, has been the reason in 2015 for up-listing of its status by the IUCN in the Red List of Threatened Species to Critically Endangered. As the Hooded Vulture is still common in the Lower Casamance, Senegal, in the Western Region of The Gambia and in Guinea-Bissau, without clear signs of a recent decrease, a survey of its current status in Dakar was undertaken and compared with historical data over the past 50 years. A strong decrease of >85% was noted from 3 000 individuals in 1969 to 400 in 2016. This decline is on the high end of the decline noticed over much of its range but in striking contrast with the apparently stable populations along the West African coast more to the south (The Gambia to Guinea). Likely causes are (1) exponential urbanisation resulting in loss of feeding sites and reduced food availability, (2) increased poisoning of feral dogs with strychnine sulphate due to an upsurge of rabies and (3) increased disappearance of suitable trees for nesting and roosting.Keywords: cutting of trees, Hooded Vulture, Necrosyrtes monachus, poisoning, population estimate, slaughterhouse sanitation, urban development

Diurnal raptors have declined significantly in western Africa since the 1960s. To evaluate the impact of traditional medicine and bushmeat trade on raptors, we examined carcasses offered at markets at 67 sites (1–80 stands per site) in 12 countries in western Africa during 1990–2013. Black kite Milvus migrans and hooded vulture Necrosyrtes monachus together accounted for 41% of 2,646 carcasses comprising 52 species. Twenty-seven percent of carcasses were of species categorized as Near Threatened, Vulnerable or Endangered on the IUCN Red List. Common species were traded more frequently than rarer species, as were species with frequent scavenging behaviour (vs non-scavenging), generalist or savannah habitat use (vs forest), and an Afrotropical (vs Palearctic) breeding range. Large Afrotropical vultures were recorded in the highest absolute and relative numbers in Nigeria, whereas in Central Africa, palm-nut vultures Gypohierax angolensis were the most abundant vulture species. Estimates based on data extrapolation indicated that within West Africa 73% of carcasses were traded in Nigeria, 21% in Benin and 5% elsewhere. Offtake per annum in West Africa was estimated to be 975–1,462 hooded vultures, 356–534 palm-nut vultures, 188–282 Rüppell's griffons Gyps rueppellii, 154–231 African white-backed vultures Gyps africanus, 143–214 lappet-faced vultures Torgos tracheliotos, and 40–60 crowned eagles Stephanoaetus coronatus. This represents a sizeable proportion of regional populations, suggesting that trade is likely to be contributing significantly to declines. Stronger commitment is needed, especially by governments in Nigeria and Benin, to halt the trade in threatened raptors and prevent their extirpation.

Despite major declines in the population of vultures around the world, noticeable increases were reported in the populations of Hooded VulturesNecrosyrtes monachusover the past decade in Accra—an important vulture habitat in Ghana. In recent times, however, there is a growing concern that the vulture numbers are decreasing even though scientific data to support this is nonexisting. As a vital zoogeographical and conservation tool, it is important to keep an up-to-date knowledge about urban bird populations amidst rapid urbanization and associated changes. Using a combination of field data, literature review, and stakeholder consultations, it was indicative that severe decline might have indeed occurred in the populations of Hooded Vultures in Accra. Evidence suggests the killing of vultures for consumption, traditional medicine, and black magic in an undercover trade with possible transboundary connections as important underlying factor. Additional factors suspected to underlie the declines include changes in management of urban facilities and destruction of roosting and nesting trees. The implications of interspecific competition with Pied CrowsCorvus albuson Hooded Vultures however remain unclear. There is an urgent need for conservation campaign and education to save the Hooded Vulture in Ghana.

The Hooded Vulture Necrosyrtes monachus is not currently listed on the IUCN Red List of threatened species, yet recent email discussions amongst a group of African raptor experts suggests this species may be in rapid decline. Information was solicited from raptor experts, as well as from published and unpublished reports, bird atlases, and individual sightings. No data was obtained for 8% of countries where the Hooded Vulture occurs and the value of the data obtained for the remaining countries varied widely in quality. Despite the variation in data quality, trends from each African region suggest dramatic population declines (mean 62%; range 45–77%) over the past 40–50 years. Some declines were documented in 20 years or less, indicating declines might be occurring rapidly in some areas. The major threats include poisoning, illegal trade for traditional medicine and bushmeat, and persecution. Based on quantitative rates of declines for each region, a revised population estimate for the species is a maximu...

Avian scavengers are common and active in the social life of southern Ghana, yet few studies consider both the ecological factors for avian presence and the avian-human interactions from human gender and age perspectives, and compare avian behaviour in both human-dominated and natural landscapes. This paper examines interactions between people, hooded vultures and pied crows in Accra and Kumasi, Ghana using both ecological and social research methods. Land use was classified for species presence into meat and waste production, vegetable marketing, non-food production, residential and central business areas, green spaces and rural areas. One hundred and eighty-four people were interviewed, classified according to age and gender. Hooded vultures and pied crows were more common in urban than rural areas, and their presence was positively correlated with human numbers. Birds were most common in meat and waste production areas, but also foraged for street discards in non-food production and residential areas, and were most rare in rural areas. Bird consumption of waste was viewed positively, while eating of other foods, close proximity and unusual behaviours were viewed negatively. Both species, especially the larger vultures, were feared as spiritual agents, this measured by odd behaviours. Women and older people had stronger beliefs, due to cultural conditioning. These human perspectives and reactions influenced avian presence. This study contributes to urban avian ecology, socio-cultural studies and urban planning.

Summary Various species of soaring birds were studied by following them in a motor-glider, mainly over the Serengeti National Park, Tanzania. The characteristics of thermal convection in the study area are described in general terms. The two vulture species of the genus Gyps live by scavenging among the herds of migratory ungulates, especially Wildebeest. They are not territorial, and gather in large numbers on kills. When raising young they may be obliged by game movements to forage at long distances from their nests. Their cross-country performance is adequate for a foraging radius of over 100 km in dry-season conditions. Their ability to compete with Spotted Hyaenas is thought to depend partly on this factor and partly on an advantage in arriving early at kills. These two species appear to find food more by watching other vultures than by searching for it directly. The Lappet-faced and White-headed Vultures are thought to be sedentary, and to depend on thorough searching of a fixed foraging territory, rather than on following migratory game. They have lower wing loadings than the Gyps vultures, and were not seen cross-country flying. They never gather in large numbers. The Hooded Vulture is a solitary nester, but it does fly across country, and does gather at kills. Vultures soar individually, and seem to be good at exploiting such phenomena as thermal streets. They do not travel in flocks. Tawny and Martial Eagles react positively to the glider, and are suspected of regarding it as potential prey. White Storks migrate between Europe and Africa, and also travel about within East Africa, by thermal soaring. They soar in flocks, and unlike vultures rely on co-ordinated social behaviour to locate thermals. In choosing their route, they often fail to react to obvious weather signs. They enter cumulus clouds from the bottom when thermalling, but probably do not climb far above cloudbase. Marabou Storks soar individually, but also sometimes travel in flocks. When doing so, they show less lateral spreading than White Storks, which reduces the effectiveness of the flock as a thermal-finding unit; on the other hand, they do seem to react to visible weather signs, like vultures or glider pilots. White Pelicans, which travel by thermal soaring between different lakes in the Rift Valley, show the most highly co-ordinated social soaring behaviour. Unlike White Storks, they fly in formation even when circling. Storks and pelicans showed more signs of alarm when approached by the glider than did the vultures or birds of prey. This could be due to their being preyed upon in flight, for instance by Martial Eagles. The basis of conventional thermal cross-country flying is outlined, and it is explained why the high wing loadings of the Gyps vultures are appropriate to their peripatetic habits. A method of thermal soaring without circling is discussed, and shown to be more readily feasible for small than for large birds. Some differences in soaring techniques between birds and glider pilots are interpreted in the light of this calculation. A case in which Black Kites apparently used this technique to soar in random turbulence is described. The cross-country speed attainable by thermal soaring should be similar to the cruising speed under power in both large and small birds. Rough calculations of the energy costs suggest that a large bird (White Stork) should reduce its fuel consumption by a factor of 23 by soaring rather than flying under power, whereas this factor would be only 2–4 for a small bird (Bonelli's Warbler). Other reasons why thermal soaring is an advantageous means of travel for large but not for small birds are also indicated.

Comparative large-scale roadside counts (8353 km), through Burkina Faso, Mali and Niger, conducted in 1969-73, were repeated 30-35 years later with the same observer and methodology and at the same season. The transect was divided into three geographical zones and between protected and unprotected areas. All diurnal raptors were recorded (22 801 individuals), as well as large game birds. Large vultures suffered a dramatic decline (98%) outside protected areas. The Hooded Vulture Necrosyrtes monachus population also collapsed in some regions, but survived in central Burkina Faso. Conversely, their abundance index did not decrease significantly in national parks. Four eagle species decreased by 86-93% and seven were not even recorded in the later study outside protected areas; by contrast, in national parks, only three species had declined marginally. Smaller Accipitridae (kites, goshawks, buzzards) also exhibited significant declines outside but not within national parks where woodland species reached their highest densities. The Common Kestrel Falco tinnunculus, mostly European migrants, declined sharply everywhere. African falcons decreased only outside protected areas. Among Palearctic migrants, Montagu's Circus pygargus and Pallid Harriers C. macrourus decreased significantly, Short-toed Eagle Circaetus gallicus less markedly, and Marsh Harrier Circus aeruginosus and Booted Eagle Hieraaetus pennatus not at all. Similar trends had previously been documented in Cameroon. They are associated with human population growth and development, global habitat degradation and ecosystem impoverishment (woodcutting, agricultural intensification, overgrazing, desertification). Heavy use of pesticides, control of locust outbreaks and overhunting have suppressed major food sources. Vultures may suffer from a shortage of carcasses, poisoning for predator control or persecution for trade of meat and body parts. Protected areas play a prominent role in the maintenance of vulture and eagle populations, even though they currently cover less than 2% of the Sudan zone and are virtually absent in the Sahel.