Showing papers in "Ostrich in 2004"

Climate change and birds: perspectives and prospects from southern Africa.

Abstract: Global climate warming, now conclusively linked to anthropogenically-increased CO2 levels in the earth's atmosphere, has already had impacts on the earth's biodiversity and is predicted to threaten more than 1 million species with extinction by 2050. Climate change in southern Africa is expected to involve higher temperatures and lower rainfall, with less predictability and a greater frequency of severe storms, fires and El Nino events. The predicted changes to birds in Africa — the continent most at risk from climate change — have hardly been explored, yet birds and many other vertebrates face uncertain futures. Here, in one of the first focused analyses of the correlates of climate change vulnerability in southern African birds, we offer a wide-ranging perspective on which species may be most at risk, and explore which traits may influence the adaptability or extinction risk of bird species. Our review suggests that small nomadic species with short generation times may be least at risk. While larger-bod...

Stopover ecology of migratory Sedge Warblers ( Acrocephalus schoenobaenus ) at Eilat, Israel

Abstract: Migrating Sedge Warblers Acrocephalus schoenobaenus were captured in Eilat, Israel, during their spring and autumn migration. Data on spring and autumn body masses, their interannual variation and the pattern of fuel accumulation were analysed. Body mass and body condition index significantly varied between the years of study in spring but not in autumn. This may be due to birds over-flying the area, but loop migration might also be involved. Sedge Warblers gain mass in Eilat, both in spring and in autumn. Birds in poor initial condition and those stopping over for a longer period gained more body mass faster. In spring, but not in autumn, the progress of the season was another important factor: late birds gained more body mass. The average rate of body mass gain was 0.179g day-1 ± SE = 0.026. This suggests that Eilat is an important staging area for Sedge Warblers in spring and to a smaller extent in autumn.

Avian clutch size in relation to rainfall seasonality and stochasticity along an aridity gradient across South Africa

Abstract: The question of how aridity might influence avian clutch size, through the influences of rainfall seasonality and environmental stochasticity (unpredictability), has received little attention. A marked east-west gradient in aridity across South Africa provides a unique opportunity to test for such influences. Using an extensive collection of nest records for 106 terrestrial bird species from the South African Nest Record Card Scheme, we tested three predictions related to rainfall seasonality and stochasticity. Analyses were conducted at two levels, the first examining each species independently, and the second grouping species into five dietary guilds. The first prediction, that clutch size should generally increase with higher rainfall seasonality (i.e. higher seasonal fluctuation of food availability), was supported, particularly in the most arid environments where food abundance is more closely linked to rainfall. Controlling for rainfall seasonality, the second prediction, that clutch size should gen...

The Birds of Morocco (an annotated checklist) by Michel Thévenot, Rae Vernon and Patrick Bergier

Abstract: 2003 British Ornithologists' Union, British Ornithologists' Club, The Natural History Museum, Tring, Herts HP236AP, UK e-mail cservs@nbnplymbridge.com 594 pages, 32 colour plates, hardcover ISBN 0 907446 25 6, price £345.00 Ostrich 2004, 75(3): 184185

An analysis of bones and other materials collected by Cape Vultures at the Kransberg and Blouberg colonies, Limpopo Province, South Africa

Abstract: We compared bones and non-faunal items collected by Cape Vultures at the Blouberg and Kransberg colonies Bones from the base of the nesting cliffs were on average longer than those from the crops and stomachs of birds Bones from the Blouberg cliff base were on average shorter than those from the Kransberg A larger proportion of bones from smaller animals was the reason for this The smaller size of the crop material was due to a greater proportion of fragmented bone Fragmentation made bones less identifiable to species The proportion of fragmented material and the particular skeletal elements discovered at the two sites were very similar and did not influence this size difference Material from these colonies was, for the most part, smaller than bones collected from other Cape and Whitebacked Vulture colonies in Zimbabwe, Botswana and South Africa Higher proportions of bones from smaller animals and smaller skeletal elements collected were the reasons for the smaller average size In wildlife reserv

The influence of nest-site characteristics on the nesting success of the Karoo Prinia ( Prinia maculosa )

Abstract: Choice of nest site has important consequences for nest survival. We examined nest-site characteristics relative to nest success in Karoo Prinias breeding in coastal dwarf shrubland, where high nest predation is the main cause of nest failure. Initially, we compared nests that failed during the building, laying, incubation and nestling stages and those from which young were successfully raised, to test whether nests that survived to progressive stages in the nesting cycle differed in their nest-site characteristics. Subsequently, we compared the characteristics of successful nests with those of unsuccessful nests. The nest-site characteristics considered included nest height, nest-plant height, nest-plant species, distance from lateral foliage edge, nest concealment, nest-patch heterogeneity and vegetation cover at four different heights. We were unable to distinguish between the nest-site characteristics of nests that failed during the various stages of the nesting cycle. Concealment was the main nest-si...

A need for continued collecting of avian voucher specimens in Africa: Why blood is not enough

Abstract: (2004). A need for continued collecting of avian voucher specimens in Africa: why blood is not enough. Ostrich: Vol. 75, No. 4, pp. 187-191.

Satellite tracking Lesser Flamingo movements in the Rift Valley, East Africa: pilot study report

Abstract: The Lesser Flamingo ( Phoeniconaias minor ) is thought to be highly nomadic. In East Africa, the number of individuals on a given lake has been shown to double or halve in a period of just two weeks. In general, interlake movements are believed to take place mostly at night. However, movement timing and patterns for individual birds are unknown. Between 12 and 23 October 2002, we affixed two solar-powered and two battery-powered satellite transmitters (PTTs) to four large (>2kg) adult male Lesser Flamingos at Lake Bogoria, Kenya. During the first three months, the four birds exhibited markedly different movement patterns. One moved 687km, making seven visits to four different lakes (mean stay: 11.4d). Another made five visits to only three different lakes (mean stay: 18.5 days), travelling only 263km. On two occasions, it remained on one lake for long periods (34 days and 70 days). A third moved among lakes in Kenya and Tanzania 44 times, visiting nine different lakes, spending an average of only 2.3 days at each and travelling a total of 4 792km in the process. The fourth is believed to have been predated on Lake Bogoria at the end of the first month. During the last six months of the study, the most active bird settled down and the behaviour of the three remaining birds was much more similar. They each spent long periods of time (e.g. 45–137d) at just one or two sites. During the study period, one bird made several short (21–81km) interlake flights during daylight hours. Flight speed was estimated to be approximately 68km h –1 during the only flight when speed could be calculated. Both solar-powered PTTs functioned well; light reaching the solar panels was not impaired by feathers or dried mineral crystals, both initial concerns. The solar-powered PTT with a pre-set ‘on/off' duty cycle performed much better than the other with no pre-set duty cycle, indicating that small solar-powered units need substantial ‘off' time to recharge their batteries, even in areas with 12h of sunlight daily. The key site network for Lesser Flamingos in East Africa consists of seven alkaline lakes in Kenya and Tanzania (Logipi, Bogoria, Nakuru, Elmenteita, Natron, Manyara and Eyasi) and an ephemeral fresh water wetland in central Tanzania (Bahi Swamp). The conservation status of these eight sites varies from well-protected (lakes Bogoria, Nakuru and Manyara) to completely unprotected (Logipi, Natron, Eyasi and Bahi Swamp), with Elmenteita being partially protected. Ostrich 2004, 75(1&2): 57–65

Breeding biology of the Cape Bulbul Pycnonotus capensis: a 40-year comparison

Abstract: I examined the breeding biology of the Cape Bulbul Pycnonotus capensis at a study site in Port Elizabeth for a comparison with the results obtained by Richard Liversidge from a study made 40 years ago. There were no differences in methods, so results were directly comparable. No differences were found between the two study periods in the timing of breeding, clutch size, number of fledglings per nesting attempt or successful nesting attempt, indicating no major shift in the life history strategy or breeding success of the population. During my study period, there was a strong calendar effect on breeding success: early nests were more likely to be successful than late ones. I found strong differences between bush species with regard to predation risk and brood parasitism risk by the Jacobin Cuckoo Clamator jacobinus. These differences emphasise the complex interaction between the timing of breeding, risk of predation and risk of brood parasitism, which influences decisions about when to start nesting and ne...

Some preliminary results of studies on the bill and tongue morphology of Gurney's Sugarbird and some southern African sunbirds

Abstract: (2004). Some preliminary results of studies on the bill and tongue morphology of Gurney's Sugarbird and some southern African sunbirds. Ostrich: Vol. 75, No. 3, pp. 169-175.

Effects of drought on birds in the Kalahari, Botswana

Abstract: Results are presented from point-counts at six sites in the Kalahari in Botswana. Counts were repeated three times: during a dry season following good rains (1991), during the next wet season when rains were far below average, and the following dry season (1992) when the area became drought-stricken. Compared to the wet season, bird numbers decreased during the drought by 37–81% and species by 8–52%; compared to the previous dry season, birds decreased by 5–71% and species by 2–47%. Bird diversity (relative to numbers) tended to increase during the wet season but was little affected by drought, except in the northern Kalahari, where a greater proportion of birds moved out in response to drought. This gave the northern Kalahari the most distinct bird community during a wet cycle, but it became again typically Kalahari during the drought. Thus, the typical Kalahari bird communities expanded their range during drought into the moister periphery. Changes in numbers, most probably resulting from (local) movements were found in many species. Most confirmed earlier reports on their nomadic nature but some, like Red-crested Lophotis ruficrista and Northern Black Afrotis afraoides Korhaan, Chestnut-vented Tit-Babbler Parisoma subcaeruleum , Ant-eating Chat Myrmecocichla formicivora , Tinkling Cisticola Cisticola rufilatus , Black-chested Prinia Prinia flavicans , Marico Flycatcher Bradornis mariquensis and Brown-crowned Tchagra Tchagra australis have not been or are not widely recognised as mobile species. Ostrich 2004, 75(4): 217–227

Global change challenges the Tawny Eagle (Aquila rapax): modelling extinction risk with respect to predicted climate and land use changes

Abstract: (2004). Global change challenges the Tawny Eagle (Aquila rapax): modelling extinction risk with respect to predicted climate and land use changes. Ostrich: Vol. 75, No. 4, pp. 204-210.

The evolution of song structure in southern African birds: an assessment of the acoustic adaptation hypothesis

Abstract: Song is critical to territory defence, mate attraction, and both species and individual recognition. According to the Acoustic Adaptation Hypothesis (AAH), habitat structure may exercise a selective force on vocal evolution such that song evolves to minimise the degradation and attenuation of acoustic signals in the particular habitat in which a species has evolved. We conducted a comparative survey of the songs of 40 South African passerine species to test the generality of the AAH. We compared pairs of congenerics, one from closed and one from grassland habitats, for seven different song attributes, including frequency, bandwidth, structure and temporal parameters. We controlled for phylogenetic effects by assessing differences between pairs of related individuals. The survey did not support the predictions of the AAH. Ostrich 2004, 75(3): 147–155

Variation in nest predation among arid-zone birds

Abstract: I examined the nesting habits and success of 11 co-existing species in an arid, sub-tropical habitat in South Africa. Nesting success ranged from 3.5% to 75.4% among species, with predation by mammals and snakes accounting for 94% of nest losses. Differences in predator avoidance behaviour (deserting the nest vs sitting tight) may explain markedly different daily nest predation risk experienced by the Double-banded Courser Rhinoptilus africanus (0.5%) and Namaqua Sandgrouse Pterocles namaqua (9.2%). Nest predation was inversely related to nest density, but this reverse density dependence may reflect a seasonal effect, as predation decreased as the breeding season progressed from spring to mid-summer. Overall, daily egg predation rates were higher than daily nestling predation rates among nine altricial species, contrary to the widely-held view that increased activity at the nest during the nestling period increases predation risk. The prediction of higher daily nest predation rates on ground-nesting species than on shrub/tree-nesting species in an open habitat was supported. Among ground-nesting species, territorial residents suffered significantly lower daily nest predation rates than nomads, suggesting that residents may use experience of local predator activity to place their nests in safer sites. Ostrich 2004, 75(4): 228–235

Nest-site partitioning in a strandveld shrubland bird community

Abstract: Nest-site selection may vary adaptively among co-existing species as a result of competitive interactions among the species or in response to density-dependent nest predation. We examined nest-site characteristics and degree of partitioning among 14 co-existing bird species breeding in dwarf strandveld shrubland at Koeberg Nature Reserve, South Africa. Habitat characteristics of nest sites differed significantly among species, indicating strong nest-site partitioning. The principal variables distinguishing nest-site characteristics among species (substrate height, cover at 1m, cover at 2m) were features that distinguish tall-shrub species which are strongly associated with patches of Dune Thicket from shorter-shrub species which are strongly associated with more open Sand Plain Fynbos. Two groups of species which differ primarily in their selection of habitat patch type within the patchy nesting landscape were identified. One group nested predominantly in low shrubs associated with open Sand Plain Fynbos....

The feeding ecology of the Lesser Vasa Parrot, Coracopsis nigra, in south-eastern Madagascar

Abstract: The diet and feeding ecology of the Lesser Vasa Parrot, Coracopsis nigra, in the littoral forest of Sainte Luce, south-eastern Madagascar are described. Forty plant species were recorded being eaten over a 14-month study period. Coracopsis nigra is a flexible feeder and eats a large variety of ripe and unripe seeds (68%), fruits (22%) and flowers (10%). Of all fruit species consumed, 70% of fruits are eaten in an unripe condition, which may lead to an advantage over potential food competitors. Detailed observations of feeding behaviour show that generally seeds are destroyed and the Lesser Vasa Parrot is considered primarily as pre-dispersal seed predator. A clear niche separation could be found among all granivorous species of the littoral forest based on fruit and seed size, ripeness of fruits, foraging height and activity pattern, Vasa Parrots feed on unripe and ripe fruits of medium size in the canopy, while Malagasy Turtledoves forage on small but ripe seeds on the ground. At night, rodents consume mainly large and protected seeds in the canopy as well as on the ground. Ostrich 2004, 75(3): 141–146

Status and abundance of the African Black Oystercatcher Haematopus moquini at the eastern limit of its breeding range

Abstract: From 1983 to 2004 the breeding population of African Black Oystercatchers along the East London coast has more than trebled. The population increase is probably due to immigration as local breeding success is low. There are three classes of birds: breeding pairs, tenants and visitors, and birds may change status during the breeding season. In the winter, birds aggregate into groups and some birds may disperse from the East London coast. The presence of African Black Oystercatchers in all months of the year shows that they are resident, but may only be resident in the general sense, and at a local level appear to be nomadic, wandering along the coast in search of resources and, in the summer, opportunities to breed. The birds remain at any locality only for as long as conditions are suitable, suggesting that the birds along the East London coast are mostly visitors that have dispersed from their natal areas in the south.

Pygmy Falcon predation of nestlings of their obligate host, the Sociable Weaver

Abstract: Rita Covas1,2*, Onno Huyser1,3 and Claire Doutrelant1,4 1 DST Centre of Excellence in Birds as Keys to Biodiversity Conservation at the Percy FitzPatrick Institute, University of Cape Town, Rondebosch 7701, South Africa 2 Present address: Institute of Cell, Animal and Population Biology, University of Edinburgh, King’s Buildings, West Mains Rd, EH8 9RB, Edinburgh, Scotland, United Kingdom 3 Present address: 2 River Close, Noordhoek, Cape Town, South Africa 4 Present address: CEFE–CNRS 1919 Rte de Mende 34293, Montpellier cedex 5, France * Corresponding author, e-mail: Rita.Covas@ed.ac.uk

Breeding and nest site characteristics of the Black-casqued Hornbill Ceratogymna atrata and White-thighed Hornbill Ceratogymna cylindricus in south-central Cameroon

Abstract: The reproductive biology of two species of African hornbill, the Black-casqued Hornbill, Ceratogymna atrata, and the Whitethighed Hornbill, Ceratogymna cylindricus, was investigated over a four-year period (1994–1997) on a 25km 2 site in lowland rainforest in south-central Cameroon Nesting attempts varied considerably among years, with the percentage of successful nests highest in 1995, with 64% and 54% of Black-casqued and White-thighed Hornbill fledging offspring, respectively There were no nesting attempts in 1994, despite the fact that hornbills were present in the study area Large differences in fruit availability were also noted across years, suggesting that reproductive activity and success are related to fruit availability Data collected from 38 nests, over four breeding seasons (1994–1997), showed a preference for nest cavities in larger trees within areas of the forest containing larger trees Hornbills did not show preferences for particular tree species, with the possible exception of Pete

Food niche segregation between the Malachite Kingfisher, Alcedo cristata , and the Pied Kingfisher, Ceryle rudis , at Lake Nokoué, Bénin

Abstract: Several species of kingfisher occur on Lake Nokoue, southern Benin, including Malachite ( Alcedo cristata ) and Pied Kingfishers ( Ceryle rudis ). Here, we compare their diet and estimate the degree of overlap in food niche by analysing contents of regurgitated pellets collected near nesting sites of Pied Kingfishers or inside the nest chambers of Malachite Kingfishers. Characteristic fish skull bones were identified using a reference collection of local fish skeletons. Malachite Kingfishers feed most frequently on fish that occur around floating vegetation, mainly Kribia sp. (56%), Hemichromis fasciatus (28%) and Sarotherodon melanotheron (8%). Important differences were found between different pairs, and between adults and nestlings, the latter being fed almost exclusively on Kribia sp. Larger fish are fed to nestlings than are eaten by the adults. Pied Kingfishers prey upon 14 different fish species, some of them being caught in the pelagic region of the lake, particularly clupeids taken by hovering. By comparison with Malachite Kingfishers, Pied Kingfishers feed on a wider diversity of prey, and take larger fish, so that the dietary overlap between the species is relatively low (O = 0.181). Ostrich 2004, 75(1&2): 32–38

Nest defence in Crowned Lapwings (Vanellus coronatus) — influences of nesting stage and ambient temperature

Abstract: 1996). In most cases, in a wide variety of species(including passerines such as flycatchers, warblers, robins,etc. and non-passerines such as owls, raptors, penguins,waders, ptarmigan, geese, ducks, etc.), parents increaseintensity of nest defence over the nesting period (Hamer andFurness 1993, Martin and Horn 1993, Sproat and Ritchison1993, Forbes

Occurrence and abundance of waterbirds at an ephemeral pan in the Northern Cape Province, South Africa

Abstract: Bi-monthly counts of waterbirds were made between March and September 2003 at an ephemeral pan in the Northern Cape Province following the first substantial inundation since 1988. Bi-annual counts between 1991 and 2003 indicated that the pan infrequently supported waterbirds, with waterfowl and small waders generally being the dominant species. During the bi-monthly counts, a total of 50 waterbird species was recorded, with the most dominant species, both in terms of numbers and duration of presence, being Black-winged Stilt Himantopus himantopus (max. 378), Cape Shoveller Anas smithii (max. 260) and South African Shelduck Tadorna cana (max. 200). Most other waterfowl and wader species were regular but in lower numbers. Species groups that occurred in limited numbers or for short periods include primarily herons, grebes, flamingos, ibises and storks. Species abundance and richness reached a peak one month after the pan was inundated, followed by a gradual decline over the ensuing two months. Ostrich 2004, 75(4): 275–284

Simultaneous decline in Steppe Eagle (Aquila nipalensis) populations and Levant Sparrowhawk (Accipiter brevipes) reproductive success: coincidence or a Chernobyl legacy?

Abstract: Visual migration surveys, especially at bottlenecks, can be a vital tool to evaluate population fluctuations in environmentally sensitive species. Raptors are considered to be important bioindicators that can help identify environmental catastrophes. Substantial proportions of the global population of Steppe Eagles (Aquila nipalensis) and Levant Sparrowhawk (Accipiter brevipes) concentrate at Eilat, Israel, during the spring and autumn migrations, but counts from seven autumn and seven spring migration surveys indicate a constant decline in Steppe Eagle numbers. Further, the number of juveniles observed in these counts dropped steadily from 30% in the early 1980s, to 1.4% in 2000. The numbers observed at Eilat are well below the range of the numerical fluctuations observed in previous surveys. In Levant Sparrowhawks, no decline in total numbers is evident, but a significant change in the adult to juvenile age ratio was noted between the population trapped in the 1980s and that sampled in the late 1990s. T...

Observations of Cape Parrot, Poicephalus robustus, nesting in the wild

Abstract: Most Cape Parrot, Poicephalus robustus, nests have been recorded in snags (standing dead trees) making monitoring of nest contents and nest activities difficult and dangerous. Here the breeding activity of a Cape Parrot pair in the cavity of a live Henkell's Yellowwood (Podocarpus henkellii) is presented. Four eggs were laid in early-August and three chicks successfully raised. Incubation period was estimated at 30–32 days. Two nestlings fledged successfully and one (the youngest) was removed because it was injured in the nest and would not have survived. Fledging period was estimated at 80 days.

Francolins, partridges and spurfowls: what's in a name?

Abstract: (2004). Francolins, partridges and spurfowls: what's in a name? Ostrich: Vol. 75, No. 4, pp. 199-203.

Song and breeding observations of suburban Olive Thrushes (Turdus olivaceus olivaceus) in Grahamstown, South Africa

Abstract: Olive Thrushes Turdus olivaceus olivaceus in Grahamstown, South Africa, were present in their territories throughout the year. Mist-net captures showed no seasonal fluctuation in the population density of adults. The breeding season had a main peak from August to November and a minor peak in April. Song output was greatest at the beginning of the breeding periods, when territorial boundaries were most keenly contested. There was a positive correlation between seasonal variation in breeding intensity and song output. The adult survival rate was estimated at 80%, and 56% of the fledglings were alive in their natal territories at the age of independence. In this study area, only females built nests and brooded nestlings. Only males sang. Both males and females defended their territories.

A re-appraisal of the taxonomic status of the Karoo Scrub-robin

Abstract: (2004). A re-appraisal of the taxonomic status of the Karoo Scrub-robin. Ostrich: Vol. 75, No. 3, pp. 156-158.

Characteristics of and competition for nest sites by the Rüppell's Parrot, Poicephalus ruepelli

Abstract: A knowledge of the nesting requirements of Ruppell\'s Parrot can aid its conservation. Nests were found during 17 months of fieldwork in Namibia and characteristics of the sites are reported here. Nests were found in woodpecker cavities. 72% of the nests were in three tree species: Faidherbia albida , Acacia erioloba and Combretum imberbe ,and 72% were in live branches. Relatively large trees were used and the entrance holes were generally tight-fitting for the birds. Both sexes worked to further excavate a cavity. Comments are included regarding territoriality, relationships with other cavity-nesting species and nest site limitation. Ostrich 2004, 75(3): 8994

Co-operative breeding in the Pygmy Falcon Polihierax semitorquatus

Abstract: Claire Spottiswoode1,2*, Eric Herrmann2, O Anne E Rasa3 and Colin W Sapsford4 1 Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, United Kingdom 2 Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7701, South Africa 3 Kalahari Trails, PO Box 77, Upington 8800, South Africa 4 29 Tuinstraat, Moorreesburg 7310, South Africa * Corresponding author, e-mail: cns26@cam.ac.uk

Variability in foraging behaviour and prey of the Common Fiscal Shrike, Lanius collaris, along an altitudinal gradient in South Africa

Abstract: Aspects of the foraging behaviour along an altitudinal gradient of four subpopulations (Durban, Merrivale, Estcourt and Harrismith) of colour-banded Common Fiscals (Lanius collaris) were analysed in summer and winter in South Africa. The shrike subpopulations showed significant differences in their attack, capture and success rates. The shrikes obtained more food during winter by increasing their attack and capture rates, and by taking larger prey items. Foraging success also increased from summer to winter in all except the Harrismith subpopulation, and was dependant upon the size of prey attacked. Perching height, attack distance, encounter time and prey length were significantly different between the sites, but only prey length showed a significant seasonal difference. It is expected that the increased attacks and captures during winter were in response to greater food demands. Common Fiscals displayed significant variability in feeding strategies and foraging parameters along the altitudinal gradient....