Polemaetus Research Articles

Predator becomes prey: Martial eagle predation of lion cubs in the greater Mara region, Kenya.

In many intact African savannah ecosystems, martial eagles are the top avian predator, while lions are the top terrestrial predator. Here, we report seven records of martial eagle predation or attempted predation of lion cubs in the greater Mara region, Kenya. These events resulted in the death of nine lion cubs, most of which were at least partially consumed, and are the first detailed records of this behaviour to be published. While these observations represent intraguild interactions, we suggest that they reflect neither intraguild predation nor interspecific killing. Rather, the ecology of both species coupled with the details of our records suggest that martial eagles opportunistically kill lion cubs purely to eat them. We hope that by publishing these records we will encourage others to share their observations of raptors predating on large mammalian carnivores, thus improving our understanding of a behaviour that we suspect may be more widespread than the current lack of evidence suggests.

Africa's overlooked top predator: Towards a better understanding of martial eagle feeding ecology in the Maasai Mara, Kenya

Raptors exert top‐down influences on ecosystems via their effects on prey population dynamics and community composition. Most raptors are sympatric with other predators, thus complicating our understanding of their relative influence in these systems. Estimates of kill rates and prey biomass recycling have been used as predation metrics that allow quantitative comparison among species and assessment of the relative role of single species within complex food webs. Few studies have produced findings of kill rates or prey biomass recycling for raptors. We used a supervised machine learning algorithm to behaviourally classify high resolution accelerometer informed GPS locations of tagged adult non‐breeding martial eagles Polemaetus bellicosus in the Maasai Mara region of Kenya to estimate kill rates and prey biomass recycling. Eagle locations classified as feeding were clustered using distance and time thresholds to identify kills and calculate kill rates. Identified kill sites were quickly ground‐truthed to confirm kills and identify prey species. We estimated kill rates for martial eagles at 0.59 kills day‐1 for males and 0.38 kills day‐1 for females, and we estimated biomass recycling per ground‐truthed kill at 1796 g for males and 3860 g for females. From our sample of identified ground‐truthed kills, ‘gamebirds' was the most frequently recorded prey category for male eagles and ‘small ungulates' was the most frequently recorded prey category for female eagles. These results position martial eagles close to sympatric mammalian top predators in trophic pyramids and provide evidence for their classification as a top predator.

Bird diversity in a Sahelian ecosystem under restoration: A study in the great Grenn wall extension area of Senegal

In this study, we survey the avian biodiversity in Koyli Alpha, Senegal, located in the extension area of the Great Green Wall (GGW) project in Senegal to restore the degraded ecosystems by the long years of drought during the 1970s in addition to anthropogenic pressures. Data are collected during a period of 52 days between July 2019 and Jun 2021 in Koyli Alpha and their surroundings, we identified the presence of avian species through daytime focal observations using transects, fixed points and trapping cameras. Thus, we recorded the presence of 198 total bird species. Species composed of 143 landbirds and 55 waterbirds distributed in 22 orders and 59 families. The most common were granivorous birds such as the Golgen sparrow (Passer luteus) and the Red-billed quelea (Quelea quelea). Among these inventoried species, three are categorized as critically endangered species (CR) (IUCN Redlist). They are the Rüppell's vulture (Gyps rueppelli), the White-backed vulture (Gyps africanus) and the hooded vulture (Necrosyrtes monachus). Additionally, the Martial eagle (Polemaetus bellicosus) is categorized as endangered (EN), and the Great grey shrike (Lanius meridionalis), the Abyssinian ground hornbill (Bucorvus abyssinicus) and the European turtle dove (Streptopelia turtur) are categorized as vulnerable species (VN). Furthermore, 37% of observed birds are palearctic migratory species.

Mapping suitable habitats for globally endangered raptors in Kenya: Integrating climate factors and conservation planning.

Raptors face global threats like electrocution, collisions, and habitat fragmentation. Many species remain understudied, and their distribution patterns are unknown. Understanding their current and future distribution is crucial for conservation. Protecting these top predators requires knowledge of their spatial distribution and environmental influences. This study addresses knowledge gaps in raptor habitats and distributions in Kenya, considering current and future climate changes. Using species distribution models and occurrence data from the Global Biodiversity Information Facility, we evaluated suitable habitats for four endangered Kenyan raptor species: Martial eagle, Secretarybird, Bateleur, and Steppe Eagle. We assessed the impact of climatic predictors on their distribution, considering two climate change scenarios for 2020-2040. Our findings reveal that raptor distribution in Kenya is predominantly concentrated in the southwestern region, extending into the central region of the country. The most significant predictors of raptor species distribution varied for each species, with Steppe eagle and Secretarybird being highly influenced by precipitation during the warmest quarter, Martial eagle being influenced by mean temperature during the driest quarter, and Bateleur being primarily influenced by precipitation during the coldest quarter. When projecting our model into the climate change scenarios for 2020-2040, all species except the Bateleur exhibited a negative range shift. The results of our study suggest that climate change may have adverse impacts on the raptor species examined. In light of these findings, we recommend implementing targeted monitoring and conducting surveys in accordance with our current model predictions. Specifically, our focus should be on monitoring areas that exhibit the highest climate suitability, as these areas are likely to undergo significant shifts in the near future. By conducting regular monitoring and engaging in further research, we can enhance our understanding of these raptor species and gather valuable data to improve the accuracy and reliability of our model predictions.

Using GPS tracking to monitor the breeding performance of a low-density raptor improves accuracy, and reduces long-term financial and carbon costs.

Traditionally, demographic monitoring of birds has been undertaken by intensive monitoring of nesting sites. However, this is challenging for low-density species, whereby the effort and costs involved in locating and monitoring remote sites can be prohibitive or even bias research findings. We show that Global Positioning System (GPS) tracking can overcome these challenges for a low-density raptor. Field monitoring of martial eagles Polemaetus bellicosus from 2013 to 2021 showed consistently poor breeding performance, with a mean productivity of 0.22 (±0.04) fledged young/pair/year. Using GPS tracking data to infer breeding performance gave a significantly higher productivity of 0.46 (±0.10) fledged young/pair/year. Breeding rate and success were also underestimated by field monitoring. These differences were likely due to logistical constraints of field monitoring, particularly relating to finding alternative nests. Comparing costs between approaches, we estimated that GPS monitoring was financially cheaper than field monitoring per sample after 10 years. Carbon costs per sample were lower for GPS-based approaches than field monitoring from the second year, and over a 10-year period GPS monitoring produced considerable savings (200% less carbon). We recommend that despite high initial costs, for long-term demographic monitoring of low-density species, or where logistical constraints make traditional field monitoring inaccurate, remote monitoring options should be considered.

Assessment of raptor species relative abundance in Hadejia Nguru Wetlands, Nigeria

Birds of prey are some of the most threatened vertebrate taxa, and in the last three decades many species have experienced severe population declines or faced extinction. The global loss of raptors per se is worrying, not just because of their charisma and flagship role, but also because reduced abundance of raptors can have cascading effects on ecosystem functioning. Raptor decline may also lead to loss of ecosystem services, sometimes acutely impacting human well-being. Therefore, population distribution, diversity and abundance of birds of prey demand investigation for potential conservation interventions. The study aimed to determine the abundance of birds of prey in Hadejia-Nguru wetlands, carried out in March to August, 2021, with a view to providing information in a bid to establish a baseline for conservation for this group of birds. Transect line method was used for the bird survey. This involved moving slowly along the transect line and recording all birds seen in and around the transect line. The survey was carried out for a period of six (6) months and each site was surveyed twice every month during the study period. Bird observation was carried out twice daily; morning between 6:00 to 10:00 a.m. and evening between 3pm to 6p.m. A pair of binoculars with magnification 7X50 was used for identification of birds visually alongside with field guide “Birds of West Africa” for identification of birds. Relative abundance and t-test were used for data analysis. The total number of birds was calculated as the number of birds seen. Transect line survey method detected a total of 1,562 individual birds of prey that belong to twenty four (24) species of 2 families. Accipitridae with 20 species and Falconidae with 4 species. The most abundant species, Yellow billed kite, black shouldered kite and gabar goshawk comprised 68.5% of all individuals seen in all wetlands in all seasons. Out of the 24 species recorded 16 are resident, 5 Palearctic migrant and 3 intra-African migrant. Four species of global conservation concern were also recorded; the Vulnerable Tawny eagle (Aquila rapax) the near threatened Red-necked falcon (Falco chicquera) and Pallid harrier (Circus macrourus) and the endangered Martial eagle (Polemaetus bellicosus ). Public awareness should be raised to inform the local populace about the importance of these species to the environment vis-à-vis protecting the man-made structures used by the bird species.

RAPTORS IN BATURIYA BIRDS SANCTUARY NORTHWESTERN, NIGERIA

The dramatic increase in human pressure, deforestation and general decrease in tree cover, overgrazing and erosion, pesticide use, over-hunting and fishing, and sometimes direct persecution of predators, all impact negatively on birds of prey population. The study aimed to determine the distribution, diversity and abundance of birds of prey in Baturiya wetlands Nigeria, carried out in March to August, 2021, with a view to providing information in a bid to establish a baseline for conservation for this group of birds. Transect line method was used for the bird survey. The survey was carried out for a period of six (6) months using transect line method and each site was surveyed twice every month during the study period. Bird observation was carried out twice daily; morning between 6:00 to 10:00 a.m. and evening between 4:00 to 6:30p.m by walking slowly along the transect line. Birds were counted as birds seen and birds inflight were also counted. Transect line survey method detected a total of 431 individual birds of prey that belong to fifteen (15) species of 2 families. Accipitridae with 13 species is the richest family in species number and Falconidae with 2 species. Out of the 15 species recorded 8 are resident, 4 Palearctic migrant and 3 intra-African migrant. Three species of global conservation concern were also recorded; the Near threatened Red-necked falcon (Falco chicquera) and Pallid harrier (Circus macrourus) and the Endangered Martial eagle (Polemaetusbellicosus ). This survey shows that, the Baturiya bird sanctuary still retained a considerable number of birds of prey species that normally occur in West Africa. However, in order to maintain the bird community and other biodiversity of the wetland, the management needs to increase conservation measures that will ensure the protection of the wetlands. This can be done through training and re-training of more forest guards to ensure protection of the wetlands.

Profiling Village Chickens Predators, Parasites and Medicinal Plants Used to Control the Parasites

Rural communities rely heavily on chickens to meet their socio-economic needs. However, predators, diseases, and parasites deprive them of nutrients required for sustained growth and development. A cross-sectional survey and key informant interviews were conducted in selected villages of Limpopo Province, South Africa to find out the parasites and predators prevalent in indigenous chickens. Medicinal plants commonly used to control parasites as well as the household heads’ views on the preservation of indigenous chickens for sustained rural food security were investigated. Qualitative data gathered through interviews was analysed thematically using Atlas Ti version 8.1.4 while the IBM Statistical Package for the Social Sciences version 25.0 was used to compute descriptive statistics and carry out cross-tabulations of quantitative data. Approximately, 72 % of the respondents reported that predation affected chicks with hens at (67 %) and cocks (63 %) following in that respective order. Snakes such as the king cobra (phakhu phakhu), birds such as the martial eagle (Goni), and wild animals, especially the genet cat (tsimba) were the predominant predators. Among the commonest parasites, fleas [Dermanyssus gallinae (thatha)] and mites [Siphonaptera (magomani)] were predominant. Sorghum (Sorghum bicolour) and aloe (Aloe vera) were the most common medicinal plants that were used to control the parasites. It is, therefore, recommended that farmers and extension officers alike, consider the profile of major predators, parasites, medical plants, and preservation of indigenous knowledge for the sustainability of indigenous chickens and enhanced rural food security.

Using web-sourced photography to explore the diet of a declining African raptor, the Martial Eagle (Polemaetus bellicosus)

ABSTRACTUnderstanding a species’ diet can be critical for effective conservation. While several traditional methods for assessing raptor diet exist, many pose inherit biases and often require extensive fieldwork that can limit sample sizes and the geographic scope of studies. This is especially true for species that nest at low densities (e.g., large eagles). Recently, several studies have demonstrated the value of web-sourced photographs in tackling ecological and evolutionary questions. Specialized software (e.g., MORPHIC) has been developed to systematically extract Google Images for this purpose. We used this approach to explore the diet of Martial Eagles (Polemaetus bellicosus). A shortage of prey is one of the proposed hypotheses for recent population declines across their range. Of the 4,872 photographs selected by MORPHIC, 254 were usable (5%). Birds, mammals, and reptiles each contributed similarly to overall identified prey. Helmeted Guineafowl (Numida meleagris) were the most important bird prey identified (12% of overall prey). The 4 most important mammalian prey species were Thompson’s gazelle (Eudorcas thomsonii; 5%), impala (Aepyceros melampus; 4%), common duiker (Sylvicapra grimmia; 4%), and banded mongoose (Mungos mungo; 4%). Reptile prey was dominated by monitor lizards (Varanus spp.; 21%). Prey class proportions differed significantly by regions with mammalian prey being more common in eastern Africa and reptile prey being more common in southern Africa. Within South Africa, reptile prey proportion was greater in the east than in the west. These corroborate existing prey composition studies. Prey composition differed between age classes, with adult eagles preying on more birds than non-adults. There was no significant difference in the average estimated prey weight by eagle age or feeding position (ground, perched, or flying). Our results suggest that this approach may offer a useful method to explore the diet for raptor species that are well photographed across their range, at minimal cost and research effort.

Densities and population sizes of raptors in Uganda’s conservation areas

Projected increases in Africa's human population over the next 40 years point to further, large-scale conversion of natural habitats into farmland, with far-reaching consequences for raptor species, some of which are now largely restricted to protected areas (PAs). To assess the importance of PAs for raptors in Uganda, we conducted an annual road survey through savanna, pastoral and agricultural land during 2008–2015. Here, we present density estimates for 34 diurnal raptor species, 17 of which were encountered largely or entirely within PAs. These included seven out of eight globally threatened or near-threatened species surveyed. Based mainly on published demographic values, we converted density estimates (birds 100 km−2) to numbers of adult pairs, for 10 resident, savanna-dependent species. We then estimated adult population sizes within conservation areas (individual PAs and clusters of contiguous PAs), based on the area of savanna in each site. This suggested that two threatened residents, Martial Eagle Polemaetus bellicosus and Lappet-faced Vulture Torgos tracheliotos, have national breeding populations of just 53–75 and 74–105 pairs, respectively. A third species, White-headed Vulture Trigonoceps occipitalis, may have a breeding population of just 22–32 pairs. In each case, at least 90% of pairs are thought to reside within Uganda's five largest conservation areas. In three cases our estimates of pair density were markedly lower than in other studies, while in six cases they were broadly consistent with published findings, often derived using more intensive survey methods. Further work is required to determine the accuracy of our estimates for individual conservation areas, and to assess the long-term viability of Uganda's threatened raptor populations.

Quantifying the decline of the Martial EaglePolemaetus bellicosusin South Africa

SummaryHuman populations in Africa are growing at a faster rate than in any other region; this growth will exert increasing pressures on the continent’s wildlife resources and declines in wildlife are already being observed. Species occupying higher trophic levels may be amongst the most useful indicators of this pressure and raptorial birds have already proven to be particularly useful in highlighting problems with their environment. The Martial Eagle is an African endemic which is thought to be declining and was recently uplisted to globally Vulnerable, although data on population trends are almost entirely lacking. The Southern African Bird Atlas Project (SABAP) 1 and 2 are citizen science projects that represent a rare opportunity, within an African context, to quantify population changes over a 20-year period. We use data from these surveys to explore changes in reporting rates for this species in South Africa between SABAP 1 (1987–1992) and SABAP 2 (2007–2012) at the scale of quarter-degree grid cells. Previous research suggests that such comparisons accurately reflect changes in breeding numbers for this species. We found an overall decline in reporting rates of c.60%, with more cells showing loss or declines (75%) than those showing colonisation or increases (25%). No differences in reporting rate change were found between provinces, suggesting a relative uniform decline across the country. There were, however, differences between biomes with declines recorded in all biomes apart from Albany Thicket, Succulent Karoo and Fynbos (south-western biomes). Declines differed inside and outside protected areas, with larger declines outside (64%) than inside (42%) protected areas, although even within large protected areas significant declines were observed. These results support the uplisting of the species’ conservation status and suggest that even within protected areas the species is not immune to the drivers of decline.

Visitors to nests of Hooded Vultures Necrosyrtes monachus in northeastern South Africa

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 case of predation of a vulture egg by a Chacma Baboon Papio ursinus, and one case of a Martial Eagle Polemaetus bellicosus predating a vulture nestling. We recommend expanding the Hooded Vulture nest monitoring programme to include more pairs.

Ranging behaviour and habitat preferences of the Martial Eagle: Implications for the conservation of a declining apex predator.

Understanding the ranging behaviours of species can be helpful in effective conservation planning. However, for many species that are rare, occur at low densities, or occupy challenging environments, this information is often lacking. The Martial Eagle (Polemaetus bellicosus) is a low density apex predator declining in both non-protected and protected areas in southern Africa, and little is known about its ranging behaviour. We use GPS tags fitted to Martial Eagles (n = 8) in Kruger National Park (KNP), South Africa to describe their ranging behaviour and habitat preference. This represents the first time that such movements have been quantified in adult Martial Eagles. Territorial eagles (n = 6) held home ranges averaging ca. 108 km2. Home range estimates were similar to expectations based on inter-nest distances, and these large home range sizes could constrain the carrying capacity of even the largest conservation areas. Two tagged individuals classed as adults on plumage apparently did not hold a territory, and accordingly ranged more widely (ca. 44,000 km2), and beyond KNP boundaries as floaters. Another two territorial individuals abandoned their territories and joined the ‘floater’ population, and so ranged widely after leaving their territories. These unexpected movements after territory abandonment could indicate underlying environmental degradation. Relatively high mortality of these wide-ranging ‘floaters’ due to anthropogenic causes (three of four) raises further concerns for the species’ persistence. Habitat preference models suggested Martial Eagles used areas preferentially that were closer to rivers, had higher tree cover, and were classed as dense bush rather than open bush or grassland. These results can be used by conservation managers to help guide actions to preserve breeding Martial Eagles at an appropriate spatial scale.

Using independent nest survey data to validate changes in reporting rates of Martial Eagles between the Southern African Bird Atlas Project 1 and 2

Repeat monitoring is vital to measure biodiversity change. However, monitoring protocols may change, as survey techniques improve or different questions are asked. Such modifications may cause difficulties when examining changes in wildlife populations. The Southern African Bird Atlas Project (SABAP) 1 and 2 are repeat national bird surveys undertaken 20 years apart. These surveys therefore offer unrivalled potential to examine bird population changes in an African context. However, changes in protocols, both spatially and temporally, between the two surveys have raised concerns over using these data to infer population changes. In this study we use independ- ent nest survey data to test whether changes in reporting rates of Martial Eagles in the Kalahari Gemsbok National Park between the two SABAP surveys were reflected in real change in numbers of nesting pairs. From 11 quarter degree squares (QDS), covering c. 8 000 km2, both SABAP and nest surveys suggested a near identical 44% decline. Levels of agreement were weaker at the individual QDS scale, although in 67% of cases the direction of change was the same using both surveys. These results suggest that comparisons in the reporting rates between SABAP 1 and SABAP 2 accurately reflect changes in the breeding population size of this species.

Eagles as indicators of ecosystem health: Is the distribution of Martial Eagle nests in the Karoo, South Africa, influenced by variations in land-use and rangeland quality?

We examined the relationship between the distribution of Martial Eagles Polemaetus bellicosus (and other large eagle species) breeding on electricity transmission pylons in the central and southwestern Karoo, South Africa, and the general environmental health of commercially managed farmland in that region. Eighty-three eagle territories were located along 1400 km of surveyed pylon line. The influence of habitat quality on eagle distributions was assessed in terms of (i) patterns of dispersion and spacing between territories, (ii) macro-scale differences between the habitat composition of eagle territories and an equivalent array of random plots, and (iii) micro-scale differences in habitat quality assessed at points within and outside of eagle territories. Territories were generally irregularly distributed along the pylon line ( p < 0.025 ). At the landscape scale, Martial Eagles significantly favoured habitats with lower and/or less predictable winter rainfall and lower primary productivity, while Tawny Eagles Aquila rapax preferred habitats with higher and/or more predictable summer rainfall and higher primary productivity. All eagles avoided areas of highest primary productivity and were absent from cultivated areas. On a local scale, habitat qualities within eagle territories were generally not significantly different to those recorded outside territories. However, eagle densities in areas stocked with indigenous game were significantly higher than in areas supporting only domestic stock (nearest neighbour distances, 7 km vs. 12 km, p = 0.025 ). This study shows that (i) large eagle distributions in the Karoo are significantly influenced by both macro- and micro-scale variation in habitat quality, and by the nature of land management, and (ii) that the Martial Eagle is potentially suitable as an indicator of ecosystem quality and functionality in the Karoo.

A multi-gene phylogeny of aquiline eagles (Aves: Accipitriformes) reveals extensive paraphyly at the genus level

The phylogeny of the tribe Aquilini (eagles with fully feathered tarsi) was investigated using 4.2 kb of DNA sequence of one mitochondrial (cyt b) and three nuclear loci (RAG-1 coding region, LDH intron 3, and adenylate-kinase intron 5). Phylogenetic signal was highly congruent and complementary between mtDNA and nuclear genes. In addition to single-nucleotide variation, shared deletions in nuclear introns supported one basal and two peripheral clades within the Aquilini. Monophyly of the Aquilini relative to other birds of prey was confirmed. However, all polytypic genera within the tribe, Spizaetus, Aquila, Hieraaetus, turned out to be non-monophyletic. Old World Spizaetus and Stephanoaetus together appear to be the sister group of the rest of the Aquilini. Spizastur melanoleucus and Oroaetus isidori are nested among the New World Spizaetus species and should be merged with that genus. The Old World ‘Spizaetus’ species should be assigned to the genus Nisaetus (Hodgson, 1836). The sister species of the two spotted eagles ( Aquila clanga and Aquila pomarina) is the African Long-crested Eagle ( Lophaetus occipitalis). Hieraaetus fasciatus/spilogaster are closest to Aquila verreauxii and should be merged with that genus. Wahlberg’s Eagle H. wahlbergi, formerly placed in Aquila, is part of a clade including three small Hieraaetus species ( pennatus, ayresii, and morphnoides). The Martial Eagle ( Polemaetus bellicosus) is the sister species of the Aquila/Hieraaetus/Lophaetus clade. Basal relationships within this clade remained unresolved. Parsimony reconstruction of the evolution of plumage pattern within Aquilini suggests that: (1) transverse barring of parts of the body plumage was lost in the Palearctic Aquila–Hieraaetus clade, (2) pale underparts in adult plumage evolved three times independently, and (3) dimorphic adult plumage is a derived character of the small-bodied Hieraaetus clade.

Raptors drowning in farm reservoirs in South Africa

Anderson, M.D., Maritz, A.W.A. & Oosthuysen, E. 1999. Raptors drowning in farm reserviors in South Africa. Ostrich 70 (2): 139–144 In the arid areas of southern Africa, the drowning of raptors in small reservoirs on farms is a significant cause of mortality. Records of 322 raptors of 29 species which drowned during 163 separate incidents have been collated. Whitebacked Gyps africanus and Cape Vultures Gyps coprotheres, and Martial Polemaetus bellicosus and Black Eagles Aquila verreauxii, were the species most frequently recovered from reservoirs. There are few records of small raptors (<300 g) succumbing in this manner. There are several possible explanations as to why raptors drown. The simplest is that these birds enter the reservoir to drink or bathe and if it is not full are then unable to climb up the structure's steep sides. There have been 12 recorded vulture mass drowning events, involving as many as 38 buds at one time. The reason for these mass drownings is probably different to the individual drowning of other raptors, with the “intimate lifestyle” hypothesis being the most plausible. There are simple, cheap and effective solutions to prevent the drowning of raptors and these are being advocated with success in the Northern Cape Province, South Africa.

Geographical analysis of vegetation structure and sightings for four large bird species in the Kruger National Park, South Africa

SummaryThe extensive spatial organization of many large-bird populations is difficult to assess. We used a geographic information system to correlate vegetation structure with random sightings for four large bird species that occur throughout the 20,000 km2 Kruger National Park (KNP), South Africa. Vegetation structure was assessed visually during 1991-1992 for the 1093 2-5′-quadrats that cover the KNP. Sightings were made during 1991-1994 of Kori Bustard Ardeotis kori, Martial Eagle Polemaetus bellicosus, Lappet-faced Vulture Torgos tracheliotus and Southern Ground Hornbill Bucorvus leadbeateri, and their nest sites. As control, comparative data on ground hornbills were also available from annual aerial censuses during 1982-1994, and from records of nest sites during 1966-1996. Each species had its highest positive correlation with a different set of vegetation categories, ranging in value from the hornbill (1.13) and vulture (1.15) up to the eagle (1.32) and bustard (1.49). Nest sites had higher correlations (hornbill 1.65, vulture 2.85) than records of free-living birds. The same vegetation categories that had the highest correlations with random sightings of ground hornbills and their nests also had the highest correlations with the more extensive and systematic data from aerial census and long-term nest records. Our method of correlating vegetation structure with random data is predictive, testable and has application to the conservation management of other sparsely distributed species.

SURVIVAL THREATS AND CONSERVATION MANAGEMENT OF RAPTORS IN THE KGALAGADI TRANSFRONTIER PARK

SUMMARY A seven year study on raptor population dynamics in the Kgalagadi Transfrontier National Park, South Africa, revealed threats to the survival of especially the resident savanna eagles (bateleur, tawny eagle and martial eagle). Threats identified included nestsite disturbance, predation on nests, drowning in reservoirs, bloodparasites and direct (e.g. shooting) and indirect (e.g. strychnine poisoning) persecution. Management recommendations are made to safeguard the raptor populations in the Park.

Breeding status and ecology of the Martial Eagle in the Kalahari Gemsbok National Park, South Africa

Herholdt, J.J. & Kemp, A.C. 1997. Breeding status and ecology of the Martial Eagle in the Kalahari Gemsbok National Park. Ostrich 68 (24): 80–85. The success of 16 nesting areas (territories) of Martial Eagles was monitored for seven successive years (1988–1994) in a protected area in the Kalahari desert of South Africa. Martial Eagles mostly laid in consecutive years (38 out of 53 attempts) and fledged, on average, 0.43 young/pair/year (38/88). Most Martial Eagles laid eggs in May and June (72.2%; n = 13 attempts). Almost all located Martial Eagle nests were in the Acacia erioloba savanna in the dry Auob and Nossob riverbeds. Martial Eagle nesting areas were spaced at intervals of 24.1 km (1144.6 km; n = 6) along the Nossob River, 15.1 km (8–34 km; n = 7) in the Auob River and 31.3 km (25–43 km, n = 4) in the interior dune area. A total of between 20 and 30 Martial Eagle pairs (20 known active nesting areas) occurred in the Kalahari Gemsbok National Park during the study period. There was no evidence of a decline in active nesting areas of Martial Eagles during the seven year study. There was no safe buffer zone around the Kalahari Gemsbok National Park and Martial Eagles were at times persecuted when foraging in the adjacent farmlands.