Showing papers in "Ostrich in 2007"

Waterbird Population Estimates

Abstract: Fourth edition, 2006, Wetlands International, Wageningen, The Netherlands 239 pages, species distribution maps, softcover ISBN 9058820319, price £25 Ostrich 2007, 78(3): 661–663

Raptor population decline in West Africa

Abstract: The roadside counts conducted in 1969–1973 through Burkina Faso, Mali, Niger and northern Cameroon (9 712km) were repeated in 2000–2004 by the same observer, using the same methods, during the same season. Overall, 28 837 Falconiforms from 51 species were recorded. The four large vultures decreased dramatically (98%) outside protected areas. The Hooded Vulture also collapsed over wide regions, but survived locally. Medium-size and large eagles, and the Secretary Bird, similarly declined >90% outside, but not inside, national parks, where woodland species also reach their highest frequency. Other African raptors were either stable or decreased significantly (e.g. Black Kite and Chanting Goshawk 35–70%). Among Palaearctic migrants, Common and Lesser Kestrels declined sharply, Short-toed Eagle, Montagu's and Pallid Harriers less significantly, and Marsh Harrier and Booted Eagle increased. Widespread habitat degradation, overgrazing, desertification, hunting pressure and heavy use of pesticides are probably i...

The status of cranes in Africa in 2005

Abstract: Of the six species of cranes occurring in Africa, the Black Crowned Crane ( Balearica pavonina ) is Near-threatened, the Wattled Crane ( Grus carunculatus ) and Blue Crane ( Anthropoides paradiseus ) are Vulnerable, the Grey Crowned Crane ( B. regulorum ) is rapidly declining, and the Atlas Mountain population of Demoiselle Crane ( A. virgo ) may be Extinct. Over the past decade, intensive coordinated surveys have resulted in significant revisions to the population estimates for Africa's cranes. The total population of Wattled Crane, previously estimated at 13 000–15 000 birds, now numbers less than 8 000 individuals and the species is in decline in as many as nine of 11 countries in its range. The B. p. pavonina population is highly fragmented and has been reduced to approximately 15 000 birds, whilst it is likely that the B. p. ceciliae population is also in decline. The East African population of Grey Crowned Crane ( B. r. gibbericeps ) has been reduced to 43 000–55 000 birds, an almost 50% decline in the past 20 years. The estimated population of Blue Cranes (>25 580) reflects a slight increase over previous estimates but is substantially lower than historical levels. Crane numbers are seriously affected by degradation and disturbance of breeding grounds and capture for domestication and trade. Ostrich 2007, 78(2): 175–184

Changes in densities of Sahelian bird species in response to recent habitat degradation

Abstract: Habitat loss in the Sahel region of West Africa has been pronounced, due to anthropogenic effects and (potentially) climate change. Although strong links have been found between conditions in the Sahel and subsequent breeding populations of certain Palaearctic migrants, the effects of these fluctuations upon Afrotropical species are unknown. We repeated bird censuses (Dec 1993 to Jan 1994, Dec 2001 and Dec 2002) at Watucal Forest Reserve, northern Nigeria, an area of rapidly degrading Sahelian woodland. We predicted declines in the abundance of woodland bird species with deforestation. For the purpose of setting up an experimental control, we also repeated bird censuses in adjacent farmland habitats that had already been deforested by the first census period: we predicted no change in abundance of farmland bird species. Tree density at Watucal decreased significantly by 82% over the eight-year period. The number of birds counted per point, the total number of species recorded per point, and the Shannon di...

African hornbills: keystone species threatened by habitat loss, hunting and international trade

Abstract: Africa is home to 23 of the world's 54 hornbill species, including the largest members of the family, the ground hornbills. None of Africa's hornbills are currently considered to be at significant risk of extinction by IUCN, and none are listed under the Convention on International Trade in Endangered Species (CITES). However, there is evidence for serious declines of African forest hornbills due to habitat loss and fragmentation, and to unsustainable exploitation for bushmeat. In addition, this paper documents a previously unreported international trade involving importation of African hornbills and their parts into the United States. In the absence of CITES reporting requirements, it is difficult to estimate the magnitude of this trade, but it appears to represent an additional threat to African hornbills, particularly large forest-dwelling species of the genera Bycanistes and Ceratogymna. Given this international trade, and other known threats to African forest-dwelling hornbills, the status of these s...

The effect of grassland shifts on the avifauna of a South African savanna

Abstract: Two distinct grassland types occur within Hluhluwe-iMfolozi Park (HiP): short stoloniferous grazing lawns and tall, tussocklike ‘bunch' grasslands. Grazing lawns are maintained by grazing mammals, among which White Rhinoceros Ceratotherium simum is of major importance. By contrast, tall bunch grasslands are promoted by frequent burning. The extent of each grassland type within the park is highly dynamic and can be altered by changes in mammal numbers and/or fire regimes. Such changes may have cascading consequences for other components of the ecosystem if they show specialisation towards one or other grassland state. This study compared avifaunal assemblages of grazing lawns and bunch grasslands to assess how bird species of the park might change with shifts in the grassland mosaic. Distinct bird communities were associated with each grassland type, including several specialists, and bird distribution was linked to vegetation structure rather than floristics. Post-fire bunch grasslands provided ephemeral habitats for short-grass specialists. Outside HiP, domestic livestock produced structurally-similar grasslands to grazing lawns and bunch grasslands, but heavy predation of birds by people reduced bird densities. Because HiP is surrounded by such communal grazing lands, the park is of key importance in conserving grassland birds on a regional scale, a factor that needs to be considered in managing the park's grassland mosaic. Ostrich 2007, 78(2): 271–279

An inventory of Sooty Terns (Sterna fuscata) in the western Indian Ocean with special reference to threats and trends

Abstract: The western Indian Ocean supports over 6 200 000 pairs of Sooty Terns, some in very large colonies. During the past two centuries colonies have exhibited increase, stability, decline and extinction. The main drivers of these trends have been habitat change and unregulated human exploitation, especially of adults; introduced predators appear to have little effect at the population level but may have prevented re-colonisation following habitat restoration. Regulated harvesting of eggs, based on increasing knowledge of Sooty Tern demography, appears to be sustainable. Some colonies now receive protection but it will be logistically difficult to extend this to all colonies. The main future threats are likely to be climate change and over-exploitation of tuna, on which Sooty Terns depend to feed. Sooty Terns should be monitored to provide insights into these and other perturbations of the marine ecosystem.

Reproductive ecology of the Cattle Egret (Bubulcus ibis) at Sidi Achour, north-eastern Algeria

Abstract: The reproductive ecology of the Cattle Egret ( Bubulcus ibis ) in a monospecific colony was monitored in 2003 at Sidi Achour, north-eastern Algeria. A set of physical characteristics were quantified to investigate their influence on breeding success. Prior to hatching, roughly one-third of the nests were subjected to vandalism in one single incident, which highlighted the anthropogenic influence on the reproductive success of Cattle Egrets breeding close to urban areas. Mean clutch size was 3.10 ± 0.13 eggs per nest (n = 31 complete clutches). The mean clutch size did not vary significantly when lost clutches were taken into account: 2.99 ± 0.09 eggs per nest (n = 86 nests). Clutch size, which exhibited a marked seasonal decline, correlated marginally with nest diameter and height above water but not with the location of a nest within a colony (central or peripheral). Hatching success for complete clutches was high (83.0%) and an average of 2.29 ± 0.18 chicks per nest survived to 12–15d of age. Growth curves of developing nestlings were estimated from repeated measurements of mass, tarsus, head and beak length, and wingspan. The last chicks (C- and D-chicks) to hatch had lower growth rates and/or survivorship than the first (A-) or second (B-) hatched chicks. L'ecologie de la reproduction du Heron garde-boeufs ( Bubulcus ibis ) a ete etudiee en 2003 dans une colonie monospecifique a Sidi Achour, dans le nord-est algerien. Une serie de descripteurs a ete quantifie pour explorer son influence sur le succes de la reproduction. Avant l'eclosion, pres d'un tiers des nids a ete vandalise lors d'un incident unique qui souligne l'influence anthropique sur le succes de reproduction du Heron Garde-boeufs nichant a proximite des centres urbains. La grandeur de ponte moyenne est de 3.10 ± 0.13 oeufs par nid (n = 31 pontes completes). La grandeur de ponte moyenne ne change pas significativement si les nids vandalises sont pris en compte. La grandeur de ponte est correlee significativement avec le diametre du nid et la hauteur de celui-ci par rapport au niveau de l'eau mais pas avec la location du nid au sein de la colonie (centre vs peripherie). Le succes d'eclosion des pontes completes est elevee (83.0%) et une moyenne de 2.29 pulli par nid ont survecu a l'age de 12–15 jours. Des courbes de croissance des poussins ont ete elaborees a partir de mesures repetees du poids, tarse, bec et envergure. Les derniers poussins eclos (C- et D-) a des taux de croissance et/ou de survie moindres que les premiers (A- et B-) poussins eclos. Ostrich 2007, 78(2): 481–487

Daytime passerine migrants over the Sahara — are these diurnal migrants or prolonged flights of nocturnal migrants?

Abstract: Passerine migrants are usually divided into diurnal and nocturnal migrants. When crossing the Sahara it was expected that nocturnal migrants would continue their flight into the day. We investigated whether migration taking place in the Sahara during daytime comprises the normal diurnal migrant species or the nocturnal ones prolonging their flight into the day. Birds departing from the Sahel in spring had to cross an ecological barrier of 300km before reaching our study site, an oasis in central Mauritania. The intensity of passerine migration measured by radar varied from night to night and decreased towards sunrise. Under good wind conditions some passerine migration continued into the day. The landing tendency (sink rate) correlated negatively with the tail wind component. Transect counts on the ground revealed very low proportions of diurnal migrants, not matching the relatively high densities of passerine migration during the day, and a high correlation between transect density of nocturnal migrants and nocturnal passage of passerine migrants. Therefore we conclude that nocturnal passerine migrants are responsible for most of the recorded daytime passage (swifts, swallows and soaring birds being excluded). Flight and landing behaviour varied with environmental conditions and nocturnal passerine migrants adjusted their flight schedules opportunistically, continuing into the day in particularly favourable winds. Ostrich 2007, 78(2): 357–362

Agonistic behaviour of Palaearctic passerine migrants at a stopover site suggests interference competition

Abstract: Records of interspecific agonistic behaviour of Palaearctic passerine migrants from their Afrotropical wintering grounds are rare. There are, however, no detailed observations from stopover sites where individuals might concentrate and depress resources that are critical for fat-depleted birds in times of high energy demand. We recorded intraspecific and interspecific interactions of Palaearctic migrant passerine birds at Ouadâne, Mauritania, a stopover site in the Sahara desert. In spring 2003 we made casual records of all aggressive behaviour we observed, whereas in spring 2004 we used focal sampling of foraging birds to record the frequency of aggression. We found that interspecific interactions occurred more often than intraspecific interactions but their relative frequency differed between species. There were also mass-dependent species hierarchies. A comparison with other studies showed that in Willow Warblers the frequency of interspecific aggression was significantly higher at the stopover site th...

Wind-governed flight altitudes of nocturnal spring migrants over the Sahara

Abstract: Flight costs make up a large proportion of energy expenditure during migration and are strongly dependent on atmospheric conditions aloft. Birds crossing the Sahara can take advantage of the fairly reliable trade-wind regime. In our study, we investigated whether birds adapt flight altitude to minimise energy or water loss. Data from free-flying birds were collected during spring migration with a tracking radar in an oasis in Mauritania, about 500km east of the Atlantic coast. Density measurements revealed the height distribution of the ongoing migration up to 4km above ground level (agl). Daily radiosondes provided information on temperature, humidity, pressure and wind profiles up to 4km agl. We compared height distributions of nocturnal migrants with predictions based on the atmospheric conditions. The two models used predicted maximum flight ranges and maximum flight durations either for energy or water constrained birds. Nocturnal migrants were flying mainly 2km agl, where predicted maximum flight ranges were generally largest. There was little difference between the two models, whereas both models were strongly shaped by the tailwind component. In addition, altitudes where water loss per flight time was minimal could explain some of the remaining variance. The results confirm that wind is the most important factor determining flight altitudes in bird migration and, at least in spring, water stress above the desert seems to play a minor role. Ostrich 2007, 78(2): 337–341

The Birds of Malawi: An Atlas and Handbook by Françoise Dowsett-Lemaire and Robert J Dowsett

Abstract: 2006, Tauraco Press and Aves, Liege, Belgium 556 pages, 16 colour plates, 625 species distribution maps, softcover ISBN 2872250042, price £25.00 Ostrich 2007, 78(1): 107–108

East African flyway and key site network of the Lesser Flamingo (Phoenicopterus minor) documented through satellite tracking

Abstract: In October 2002, four adult Lesser Flamingos were tagged at Lake Bogoria, Kenya: two with solar-powered platform transmitter terminals (PTTs) and two with battery-powered PTTs, one of which stopped...

Habitat preferences of birds in a montane forest mosaic in the Bamenda Highlands, Cameroon

Abstract: Although the high species richness and endemism of birds in the Bamenda Highlands has attracted ornithological research for decades, most studies have been restricted to bird communities of continuous montane forests. Instead, we focused on a mosaic landscape with montane forest remnants, where the habitat preferences of birds remain unknown. We performed an assessment of habitat associations of birds in the Bamenda Highlands in the Cameroon Mountains. Using a point count census method, we detected 71 species within the study area. The most abundant species were the Northern Double-collared Sunbird Cynniris reichenowi, the Oriole Finch Linurgus olivaceus, the Common Stonechat Saxicola torquata, the Thick-billed Seed-eater Serinus burtoni, the Black-crowned Waxbill Estrilda nonnula, the Brown-backed Cisticola Cisticola chubbi and the Yellow-breasted Boubou Laniarius atroflavus. Canonical correspondence analysis revealed that the most important environmental gradient structuring the bird community follows t...

Conservation priorities for the Blue Crane (Anthropoides paradiseus) in South Africa — the effects of habitat changes on distribution and numbers

Abstract: Detailed knowledge on population numbers, habitat preferences and threats is lacking for the Blue Crane ( Anthropoides paradiseus ), which is endemic to southern Africa and is South Africa's national bird. Using the South African Bird Atlas Project Blue Crane distribution as the accepted distribution of the species, this analysis has shown three distinct core areas for the population determined by a core index value. The largest of these core areas occurs in the central Karoo region covering 153 153km 2 . The next largest core area was in the Eastern Grassland region covering 137 838km 2 . The final core area is located in the areas known as the Overberg and Swartland of the Western Cape province, encompassing 23 440km 2 . The annual National Crane Census in South Africa, which covered 40% of the Blue Crane's distribution, has resulted in the determination of the actual minimum population size of 25 520 individuals. An assessment of the Blue Crane's distribution in relation to the vegetation composition of the three core areas shows that it has experienced a dramatic decline in population numbers in the Eastern Grasslands core area, where a significant degree of grassland transformation and fragmentation has occurred. The Central Karoo population has remained stable and comprises 42.4% of the current national population estimate. More than 42% of this core area comprises Nama Karoo vegetation with little habitat transformation. The most significant change has occurred in the Western Cape, which historically consisted of unsuitable Blue Crane habitat. The conversion of Fynbos and Renosterveld to ‘artificial grasslands' through agricultural developments has created a favourable habitat for Blue Cranes, with this core area, comprising only 7.6% of the total core area in the country, having 47.4% of the national population. The conservation of the Blue Crane in these core areas relies on private landowners implementing management plans that allow the Blue Crane to coexist in an agricultural landscape. Knowledge through applied research will allow the identification of preferred habitats, breeding locations and suitable management activities. The landscape approach of conservation allows the benefits of ecosystem management to be realised for both people and the biodiversity elements. Ostrich 2007, 78(2): 205–211

Impact of Eucalyptus plantations on the avian breeding community in the East Usambaras, Tanzania

Abstract: The nesting bird species in natural forests and Eucalyptus plantations on the Amani Plateau, East Usambara, were studied during the breeding season of September 2003 to March 2004. Some forest birds — like barbets, batis, broadbills, doves, flycatchers, greenbuls, hornbills, and tinkerbirds — utilised similar nest sites with respect to plant species or forest structure in both Eucalyptus plantations and natural forests. Very low densities of nests in Eucalyptus plantations indicate that forest bird species have mostly failed to adapt to this habitat. However, management practices may contribute to the low densities of nests in these plantations. A concerted effort should be made to protect the remaining natural forests and management of the Eucalyptus plantations should take the breeding seasons of local birds into account.

Composition and foraging behaviour of mixed-species flocks in two adjacent African woodland habitats: a spatial and temporal perspective

Abstract: We examined temporal and spatial effects on (1) overall flock composition, and (2) aspects of the foraging behaviour of three bird species commonly participating in mixed-species flocks in mixed and Acacia woodland across the winter season in South Africa. Foraging observations were compared when birds were alone or with conspecifics, against when in mixed-species flocks. The two habitats differed with respect to the presence of the Southern Black Tit Parus niger, a leader species in mixed woodland but largely absent from Acacia woodland. Flock species richness within mixed woodland, but not Acacia woodland, increased significantly as the season progressed. Enlarged flock size resulted from a general increase in flocking tendency of all species. At the species level, the Long-billed Crombec Sylvietta rufescens and the Chinspot Batis Batis molitor showed clear feeding benefits within flocks, whereas tits obtained no feeding benefit. Crombecs and batises also changed foraging location when entering mixed fl...

The Atlas of the Birds of Central Mozambique

Abstract: 2005, Endangered Wildlife Trust and Avian Demographic Unit 321 pages, species distribution maps, softcover ISBN 0799222844, price R235.00 Ostrich 2007, 78(3): 659–660

The effects of fire on grassland bird communities of Barberspan, North West Province, South Africa

Abstract: Considering the frequent nature of fires and resultant drastic change in habitat following fire, research on the effects of fire on birds in the grasslands of South Africa is surprisingly scarce. For at least five months after burns we followed the changes in bird species composition, species richness and densities of two controlled burns and one accidental fire at the Barberspan Nature Reserve in grasslands that had not been burned or grazed in 10 years. Compared with the control areas, species richness and densities increased in the burned areas immediately following the burns, with more species and birds recruited to the burned areas than were lost. Immediate post-burn opportunists tended to be larger species, and the biomass increase mirrored the increases in species richness and densities in burned areas. Avian species richness, densities and biomass tended to return to the initial conditions after a number of months. Although the bird communities from two controlled-burns differed before the burns, they converged to a characteristic immediate post-burn composition. Five months after the burns however, the bird communities reflected a pre-burn composition. Indications were that birds in an area larger than that burned were affected. Mosaic burning, with shifting large and small patches, should be considered on a landscape scale. Ostrich 2007, 78(3): 591–608

Black Eagles and hyraxes — the two flagship species in the conservation of wildlife in the Matobo Hills, Zimbabwe

Abstract: The Black Eagle (Aquila verreauxii) in the Matobo National Park is heavily dependent on two hyrax species, which form 98% of the diet. This raptor has been the subject of study in the Matobo Hills for the past 45 years. Its two main prey species, the Yellow-spotted Hyrax (Heterohyrax brucei) and the Rock Hyrax (Procavia capensis), have been under study for the past 13 years. There are three categories of land use in the Matobo Hills — national park, commercial farmland and communal land — and therefore varying levels of protection for the raptor and its prey. Local communities within the Matobo Hills depend on the hyrax as their main source of protein. This heavy utilisation has lead to population declines in both the prey (hyrax) and the raptor in some areas. In an effort to reverse or reduce this imbalance, since 1995 wildlife conservation education programmes have been introduced, focusing on 21 schools immediately surrounding the Matobo National Park. This educational programme is aimed at conserving ...

Abundance, movements and habitat use by African Grey Parrots (Psittacus erithacus) in Budongo and Mabira forest reserves, Uganda

Abstract: Populations of African Grey Parrots are threatened by increased forest loss and the pet trade. Budongo forest reserve has, for over 60 years, been subjected to selective logging. Mabira forest reserve faces human pressures characterised by extractive disturbances, and agricultural activities with increased boundary settlements. We estimated parrot populations using the ‘forest limiting circumference' method, and ‘encounter rate approach' for general abundance and forest type associations, respectively. Counts were conducted on flyways in the morning and evening of one day, and observations on food tree location and preference were made by forest type and time of day. Total parrot populations were estimated at 714 in Budongo and 342 in Mabira. Mean numbers of flocks observed per flyway were 4.18 ± 4.33 and 4.70 ± 2.71 for Budongo and Mabira, respectively. Similarly, flock sizes varied from 2.59 ± 2.95 in Budongo to 2.87 ± 3.06 in Mabira forest. High encounter rates were recorded in disturbed/secondary forests during foraging activities and these coincided with areas of abundant fruiting trees. Movements into and out of main forests followed regular flyways and inter-forest movements increased with forest fragmentation. However, the presence of forest strips seemed to enhance the stability of flyways. While African Grey Parrots in Budongo may benefit from its large size, the Mabira population is likely to face a greater threat of further decline. More protected areas are needed to maintain viable populations, and future research should focus on breeding ecology, population monitoring and the impact of trade activities on this species. Ostrich 2007, 78(2): 225–231

Impacts des éclairages urbains sur les pétrels de Barau, Pterodroma baraui sur l'Ile de la Réunion et mesures pour réduire ces impacts

Abstract: The island of Reunion (55'30E; 21'00S) has two endemic petrels, one of which is Barau's Petrel (Pterodroma baraui), classified as 'Endangered' (IUCN 2000). This species is under threat from several sources: predation by introduced mammals, poaching, and strandings. Petrel deaths resulting from city lights is a recent phenomenon related to urbanisation of the island. Young birds on fledging are attracted by the lights, and fall to the ground where they risk being killed. Rescue operations have mobilised the local population, and between 1995 and 2004, 3 762 Barau's Petrels were retrieved. The main stranding sites were identified. The most attractive structures were the illuminated road network (37.8%) and sports complexes (24.4%) (n = 1 652). Experiments on Puffinus lherminieri bailloni showed that the least attractive lighting colours are red and yellow, the most attractive green and blue. These findings enable us to propose measures to ameliorate the impact of city lights on the young petrels, by adjusti...

Breeding biology and nest site characteristics of the Rosy-faced Lovebird Agapornis roseicollis in Namibia

Abstract: The breeding biology of the Rosy-faced Lovebird Agapornis roseicollis was investigated in its natural habitat at three Namibian localities: Claratal, Hohewarte and Haris. The lovebird nests in colonies often shared by Sociable Weavers Philetairus socius. Birds nested in trees at a mean height of 3.8m, on telephone poles at 6.6m, windmills at 11.2m, and artificial nest boxes at 3.3m. Acacia erioloba and A. karroo were most often used for nest location. Nest tree habitats had low density vegetation with short (4m) trees, mostly A. erioloba, spaced at distances of about 10m. No specific nest entrance orientation was chosen. Birds obtained nest materials from the bark of small branches, branchlets from the tips of branches, twigs, sticks, leaves and thorns of trees, predominantly A. karroo, A. erioloba, Ziziphus mucronata and Boscia albitrunca. Nine colonies, comprising 20 nests, were monitored every four days to establish incubation and fledging periods. Rearing and fledging of chicks was found to be success...

Distribution, structure and simulation modelling of the Wattled Crane population in the Marromeu Complex of the Zambezi Delta, Mozambique

Abstract: The status of the Vulnerable Wattled Crane (Grus carunculatus) in Mozambique is poorly known, but historical accounts indicate that the species was previously more abundant and widespread than today. Annual surveys during 1995–2002 suggest a core population of about 120 breeding pairs remains in the Zambezi Delta region. Wattled Cranes in the delta are exclusively associated with sedges of the genus Eleocharis, the tubers of which provide the adult cranes' main food supply. The main Eleocharis areas in the delta, and those supporting the highest density of Wattled Cranes, occur below the adjacent Cheringoma escarpment, where unregulated streams flow onto the floodplain. These wetlands experience some seasonal inundation in all years — conditions essential for the production of underground tubers — and high soil penetrability to enable the cranes to extract tubers. Eleocharis tuber production and soil penetrability is extremely low in the remaining vast areas of the delta that no longer receive regular ann...

Effects of habitat fragmentation on bird communities of sand forests in southern Mozambique

Abstract: We investigated the influence of forest fragment size and isolation on the bird assemblages in the species- and endemic-rich sand forests of the Maputaland Centre of Endemism, southern Mozambique Point-centre surveys were conducted across 12 sand forest patches that varied in size and isolation Patch size and isolation had little influence on bird species richness, but the number of individuals decreased significantly with increasing isolation Furthermore, bird abundances were correlated to a combination of the size and isolation of patches Many forest specialists, in particular large-bodied frugivores, were highly sensitive to reduced patch size and increased distances between patches Further fragmentation of the landscape may therefore impair the ability of these forests to support viable populations of forest specialists

Movements of waterbirds within Africa and their conservation implications

Abstract: Waterbirds in Africa have developed diverse strategies to exploit the wide variety of African wetlands. Whilst some species are largely sedentary, especially those in relatively static tropical climates, most demonstrate movements in response to changing seasons and environmental conditions. The onset of rain is an important trigger for migration: some waterbirds are harbingers of the rainy season, whilst others follow in the wake of rain. However, levels and timing of rain can be unpredictable and rain may not fall at all some years. When rain falls in arid and semi-arid areas, productive temporary wetlands can appear rapidly and attract large numbers of waterbirds, many of which are partially nomadic. This unpredictability presents difficult management scenarios. Overall, waterbird movements within Africa are poorly understood, which limits our abilities to conserve waterbirds in Africa and to implement the African-Eurasian Migratory Waterbird Agreement. It will take major resources and many years befor...

Notes on Angolan birds: new country records, range extensions and taxonomic questions

Abstract: Details of 12 species and 16 species from species splits that are new to the list of birds for Angola are presented. Range extensions and new distribution records for a further 50 species, including 16 species previously considered to have very restricted ranges, are listed and discussed. Mis-identified species, or species for which Angolan records are doubtful, are listed together with reasons why each of the species is unlikely to occur in the country. Several taxonomic issues around some of the Angolan near-endemic bird species are highlighted, together with some discussion on potential species splits.

Nesting success and within-season breeding dispersal in the Orange-breasted Sunbird Anthobaphes violacea

Abstract: Nest predation is a primary cause of nesting mortality for many bird species, particularly passerines. Nest location can affect predation, and it has also been demonstrated that predation risk can alter nest site selection. Birds can limit predation risk by selecting specific habitat characteristics; by changing nest site characteristics between attempts; and by dispersing between nesting events. Here we report breeding data from a population of Orange-breasted Sunbirds Anthobaphes violacea (L.), for a single breeding season in the Jonkershoek Nature Reserve, South Africa. Neither shrub type nor nest height was found to affect the outcome of a nest. For subsequent breeding attempts, birds were not more likely to change the type of shrub in which they nested after a predation event than when the attempt was successful, nor did they change the height of their nest. However, we found that the distance between a nest and the subsequent one was significantly shorter after a successful nest than after an unsucc...

Identification of potentially competing Afrotropical and Palaearctic bird species in the Sahel

Abstract: Areas experiencing a seasonal influx of migrants may be expected to have a high potential for competition between resident and migrant populations. Described differences in foraging behaviour and microhabitat selection between Palaearctic and Afrotropical species have been ascribed to competition between these groups. The first step in the assessment of whether there are any interspecific competitive interactions must be the identification of species with the greatest overlap in habitat selection and foraging method. Our results provide a tool for identifying species with the greatest potential for interspecific competition. These species should be the focus of any further examination of competition within the Sahel.

Seasonal and annual dietary changes in Lesser Kestrels Falco naumanni wintering in Lesotho

Abstract: The diet of Lesser Kestrels Falco naumanni wintering in an agriculturally-transformed area in Lesotho was studied by means of pellet analysis. Orthopterans, beetles and solifugids (sun spiders) comprised the staple food of the wintering Lesser Kestrels. Small vertebrates, termite alates, earwigs and scolopendrans supplemented the diet. The proportion of pellets containing scarabaeid and carabid beetles, as well as those containing locusts and crickets, increased as the wintering season progressed, while the proportion of pellets containing solifugids decreased during the same period. Significant differences in diet composition were recorded between the 1998/1999 and 1999/2000 wintering seasons. Ostrich 2007, 78(3): 615–619