Showing papers in "Ostrich in 2010"
TL;DR: In this article, a survey of representative power lines in the Overberg region of the Western Cape was conducted, and the authors found that birds of at least 18 species were killed on power lines.
Abstract: Avian mortality on power lines in South Africa is currently recorded on the Central Incident Register (CIR), which is a collation of incidentally reported cases. The true scale of the problem is unknown, so we report here on a survey of representative power lines in the Overberg region of the Western Cape. On the 199 km surveyed, 123 birds of at least 18 species were found. Collisions were more common than electrocutions, apparently killing 88% of the birds found on distribution lines. Large terrestrial birds were the most numerous victims, with large numbers of Blue Cranes Anthropoides paradiseus and Denham's Bustards Neotis denhami killed. In comparison with mortality rates from the CIR, we estimate that only 2.6% of power-line mortalities are reported, emphasising the importance of systematic surveys in quantifying mortality and directing mitigation. Our survey highlights the general hazard that power lines pose to avifauna, and the urgent need for further research into the population impacts of the hi...
29 citations
TL;DR: In this paper, a total of 32 African White-backed Vulture nests were monitored in the Masai Mara National Reserve over a five-year period between 2003 and 2007, and the mean nesting success was 59% which was comparable to that of populations from southern Africa.
Abstract: Vulture populations have declined globally as well as regionally within Africa. Little is known about the status of the African White-backed Vulture Gyps africanus in Kenya, but ongoing studies indicate that its population has declined over the last two decades. A total of 32 African White-backed Vulture nests were monitored in the Masai Mara National Reserve over a five-year period between 2003 and 2007. Mean nesting success was 59%, which is comparable to that of populations from southern Africa. Nearest neighbour distances were significantly closer in wooded habitats (‘trees and shrubs savanna’) than in more open grassland habitats (‘open low shrubs’). Based on nearest neighbour distances, the estimated total breeding population within the Masai Mara National Reserve is 1 106 pairs, a figure that may be an overestimate and requires ground-truthing. Collecting baseline data on numbers of breeding pairs and regular nest monitoring are essential in order to assess the impact of various threats to vultures...
25 citations
24 citations
TL;DR: During 2002–2007, a growth curve was derived for developing nestlings and the impact of an ectoparasite (mite) infestation upon nestling's growth was considered, and 73 food boluses regurgitated by nestlings were examined and 329 prey items were identified.
Abstract: During 2002–2007, we assessed the status of the Purple Heron Ardea purpurea in Numidia, Algeria by surveying all the major wetlands in the region. We located six distinct breeding sites; four of these were not previously known. We also investigated nest site selection and determined the species’ reproductive success at Dakhla, a dunary pond during two successive years (2006 and 2007). The egg laying period was comparable to that reported for southern Europe (March-May) and a seasonal change of breeding success was recorded. A growth curve was derived for developing nestlings and the impact of an ectoparasite (mite) infestation upon nestling's growth was considered. We also examined 73 food boluses regurgitated by nestlings and identified 329 prey items. Fish, mainly Gambusia holbrookii and Cyprinus carpio, dominated by mass, whereas insects, mainly aquatic Coleopteran larvae and aeshnids (Odonata), were the most frequent prey (67.1%). Loss of habitat is identified as a major threat to the future of coloni...
22 citations
TL;DR: Similarity in the stomach contents of both species indicates that both may face similar threats with regards to pesticide exposure, habitat alteration and persecution in their austral non-breeding range.
Abstract: The diets of Falco amurensis and F. naumanni were investigated by analysing the respective stomach contents of 64 and 22 individuals killed during a severe thunderstorm in December 2004. Interpretations of diet were made by considering (1) biomass of dietary items and (2) presence/absence of dietary items in the stomachs analysed. A single beetle (Coleoptera) species, cf. Heteronychus arator , made up the majority of stomach contents when using both methods. Other Coleopteran taxa did not comprise a significant proportion of the biomass in each stomach but were well represented in the stomachs of many individuals. Taxa less represented included Rodentia, Solifugae, Orthoptera, Hymenoptera and other unidentified prey items. Although both F. amurensis and F. naumanni sometimes feed on birds, we believe that all feathers found in stomachs were ingested during preening activities or were accidentally introduced during excision. The presence of a single beetle species in the diet of both species demonstrates the importance of episodic and/or predictable arthropod irruptions as a food source for these two migrant falcon species. Similarity in the stomach contents of both species indicates that both may face similar threats with regards to pesticide exposure, habitat alteration and persecution in their austral non-breeding range. OSTRICH 2010, 81(1): 39–44
16 citations
TL;DR: Using stable isotopes to trace resource acquisition and trophic position in four Afrotropical birds with different diets using stable isotope ratios is used to solve the mystery of the ostrich's migratory habits.
Abstract: (2010). Using stable isotopes to trace resource acquisition and trophic position in four Afrotropical birds with different diets. Ostrich: Vol. 81, No. 3, pp. 273-275.
15 citations
TL;DR: In this paper, the authors argue that the policy aspects, which have not been so widely researched so far, have considerable effects on the efficiency of mitigation measures and the role of contextual factors, stances and relations of different actors, plus actions and tools applied in the solution process.
Abstract: Bird mortality caused by electric power lines has been an issue in several countries for more than three decades now Despite serious efforts by conservationists, government agencies and utility companies assisted by increasing biological and technological knowledge, only a minority of countries has made significant progress in mitigation In the present article I argue that the policy aspects, which have not been so widely researched so far, have considerable effects on the efficiency of mitigation measures The problem management methods of four countries—Hungary, Slovakia, South Africa and the USA—are discussed in detail to reveal success criteria The role of contextual factors, stances and relations of different actors, plus actions and tools applied in the solution process, are demonstrated together with the resulting outcomes To help strategic planning, I review favourable solution methods (volunteer agreements, legislative steps, mixed solutions, etc) used in different country-specific contexts,
13 citations
TL;DR: The Crested Francolin Dendroperdix sephaena is a common gamebird in sub-Saharan Africa but its vocal behaviour is poorly recorded and statistics on call characteristics during the breeding and non-breeding seasons are captured.
Abstract: The Crested Francolin Dendroperdix sephaena is a common gamebird in sub-Saharan Africa but its vocal behaviour is poorly recorded. A fixed area (24 km2) in the Borakalalo National Park (North West province, South Africa) was traversed during December 2007 to January 2009 and 140 Crested Francolin groups were enticed with playback calls and their calls recorded. The coveys were recorded to identify different calls and to capture statistics on call characteristics during the breeding and non-breeding seasons. Sonograms were produced to analyse and compare the structural characteristics of calls. The Crested Francolin possesses a basic communication system of eight distinctive calls that is similar to the repertoire size of other non-passerines. The duet is a cooperative call by a male and female to advertise, among other functions, territorial occupancy. Males produce a call similar to but different from the duet that advertises reproductive neutrality to avoid physical clashes. Male and female calls could ...
12 citations
TL;DR: This paper measured the density of five species of Palearctic warblers (Sylviidae, Nectariniidae, Malaconotidae and Ploceus luteolus) and 10 species of Afrotropical gleaning passerines at 16 sites in the Sahel of northern Nigeria during two winters.
Abstract: Declines in populations of Palearctic migrants wintering in the Sahel of Africa have been linked to the impacts of climate change and habitat degradation in the region. Despite this, there is an almost complete lack of data on the density and distribution of Palearctic migrants wintering in the Sahel and whether they have the same habitat requirements as similar, resident Afrotropical species. We measured the density of five species of Palearctic warblers (Sylviidae) and 10 species of Afrotropical gleaning passerines (Sylviidae, Nectariniidae, Malaconotidae and Ploceidae) at 16 sites in the Sahel of northern Nigeria between October and April during two winters. Two species of Afrotropical gleaner (Hippolais pallida and Ploceus luteolus) showed seasonal variation in abundance, but this variation was unlikely to have decreased Afrotropical densities sufficiently to change the degree of competition experienced by Palearctic migrants. This observation, combined with a positive correlation between abundances o...
12 citations
TL;DR: Leucocytozoon ugwidi and Haemoproteus skuae from the Subantarctic Skua Catharacta antarctica are described in this article.
Abstract: New species of haematozoa, namely Leucocytozoon ugwidi sp. nov. from the Cape Cormorant Phalacrocorax capensis and Haemoproteus skuae sp. nov. from the Subantarctic Skua Catharacta antarctica, are described. These are the first species to be recorded from the families Phalacrocoracidae and Stercorariidae, respectively.
11 citations
TL;DR: Assessment of body sizes between male and female plovers breeding in Madagascar found significant differences in body size among the four species, and between sexes, and it is proposed that SSD may be more common than currently acknowledged.
Abstract: Many small plovers Charadrius spp. have sexually monomorphic plumage and cryptic sexual size dimorphism. The objective of our study was to assess the variation in body sizes between male and female plovers breeding in Madagascar. We collected blood samples and data on adult body sizes of four small plovers (Madagascar Plover Charadrius thoracicus, Kittlitz's Plover C. pecuarius, White-fronted Plover C. marginatus and Three-banded Plover C. tricollaris), and used molecular genetic markers to sex the adults. We found significant differences in body size among the four species, and between sexes. Furthermore, individuals from the southern ecoregion tended to be larger than in the western ecoregion. The Madagascar Plover's body size was significantly more dimorphic than the Kittlitz's and White-fronted Plovers. Breeding Malagasy plovers' show significant sexual size dimorphism (SSD): Madagascar Plover females were heavier and had longer wings than males, whereas the males had longer tarsi; in White-fronted Plover only wing length was different between the sexes. Taken together, our work reports SSD in small African plovers that exhibit monomorphic plumage, and we propose that SSD may be more common than currently acknowledged; we term this 'cryptic sexual size dimorphism'. Our results also suggest sexual selection and/or natural selection exert different pressures on body size in different Malagasy plover species.
TL;DR: The authors examined seasonal and spatial variation in wintering densities of Northern Wheatears in northern Nigeria, and explored the species' habitat associations on the wintering grounds to assess the likely effects of habitat change in the Sahel on this species.
Abstract: Palearctic migrant birds are declining, including the Northern Wheatear, and some of the causes of these declines are likely to be operating on their wintering grounds in Africa. We examined seasonal and spatial variation in wintering densities of Northern Wheatears in northern Nigeria, and explored the species’ habitat associations on the wintering grounds to assess the likely effects of habitat change in the Sahel on this species. Densities of Northern Wheatears across northern Nigeria were calculated from point count data gathered during two winters (2000 and 2001) using Distance software, and the relationships between Wheatear presence and habitat variables collected from the same points were explored using general linear models. During mid-winter and early spring, densities of Northern Wheatears peaked, with significantly more birds present in western than eastern study sites. The probability of wheatear occurrence was correlated with Balanites and Salvadora tree density and mean tree height. The Nor...
TL;DR: In this paper, the authors studied trends in populations of the endangered Sokoke Scops OwlOtus ireneae in the Arabuko-Sokoke Forest, Kenya.
Abstract: (2010). Disconcerting trends in populations of the endangered Sokoke Scops OwlOtus ireneae in the Arabuko-Sokoke Forest, Kenya. Ostrich: Vol. 81, No. 2, pp. 155-158.
TL;DR: Differences in infection prevalence between sexes was correlated to time spent being active at the nest, with a marked reduction in female infection due to incubation within a tunnel-shaped nest providing protection from vectors, resulting in reduced immunocompetence.
Abstract: Over a two-year period, 945 adult Cape Weavers Ploceus capensis were mist-netted with a bias towards 632 male and 308 female birds. Blood smears presented avian haemosporidia in 58.79% of males and 61.90% of females, representing five species from three genera: one avian kinetoplastid haemoflagellate Trypanosoma everetti with 0.28% infection rate, Haemoproteus queleae (69.45%), Leucocytozoon bouffardi (23.91%), and Plasmodium species (5.76%). Double infections occurred in 40 birds (11.52%), with females having the greatest number. Differences in infection prevalence between sexes was correlated to time spent being active at the nest, with a marked reduction in female infection due to incubation within a tunnel-shaped nest providing protection from vectors. Commencement of the breeding season coincided with increased parasite prevalence in both sexes, correlating to energy expenditure on reproductive effort, resulting in reduced immunocompetence. Recorded seasonal spring relapse is synchronised with peak b...
TL;DR: It is suggested that sex, geographical area and possible annual environmental variations may all influence the timing of moult in local populations of Southern Red Bishops Euplectes orix in relation to sex and geographical region.
Abstract: Using the SAFRING database and the Underhill-Zucchini model of primary moult, we analysed the timing of wing moult in Southern Red Bishops Euplectes orix in relation to sex and geographical region. Birds from the winter rainfall region in the south-western sector of the Western Cape start the annual moult more than two months before any other population, but there were no significant differences in starting date within the summer rainfall region. There were striking differences in the estimates of moult duration (62–114 d), which did not follow a consistent pattern in relation to sex or geography; annual variation within a region may be an additional factor. Throughout southern Africa, both sexes showed a trend for longer-winged birds to take more time to complete their moult. We suggest that sex, geographical area and possible annual environmental variations may all influence the timing of moult in local populations. In this sexually dimorphic species, males are consistently longer-winged and heavier tha...
TL;DR: Assemblages of waterfowl (Anatidae) at two cattle feedlots 120 km apart in Gauteng province, South Africa are described, finding that long- and short-distance movements byWaterfowl may be triggered not only by rainfall, but also by the productivity of water bodies.
Abstract: Assemblages of waterfowl (Anatidae) at two cattle feedlots 120 km apart in Gauteng province, South Africa are described. Yellow-billed, Fulvous and White-faced Ducks, Cape Shoveller, and Cape and R...
TL;DR: Investigation of the differences in the timing and duration of primary wing moult between males and females of sexually dimorphic passerines from the Western Cape, South Africa found variations in the patterns of moult were discussed in the context of differences in parental care.
Abstract: SAFRING ringing data was used to investigate the differences in the timing and duration of primary wing moult between males and females of sexually dimorphic passerines from the Western Cape, South Africa. In the sunbirds, weavers and canaries that were considered, the males generally started moult before the females, whereas this was not so for other species. In the species where males started moult before the females, the standard deviation of the start of moult was generally smaller in the males and the males generally took longer to moult. These differences in the patterns of moult are discussed in the context of differences in parental care between males and females of each species and within their taxonomic groups. OSTRICH 2010, 81(1): 63–67
TL;DR: Body temperature traces obtained from Acacia Pied Barbets in a field laboratory in the Kalahari Desert reveal reductions in Tb to below 32 °C during the rest-phase, suggesting that in natural habitats this species may routinely exhibit facultative hypothermia.
Abstract: Torpor has been documented in a number of avian orders, but our understanding of the phylogenetic distribution of this phenomenon is far from complete, and several groups have yet to be investigated. We examined patterns of rest- and active-phase thermoregulation in Acacia Pied Barbets Lybius leucomelas and Crested Barbets Trachyphonus vaillantii held in outdoor aviaries, using surgically-implanted miniature data loggers to record body temperature (Tb). Both species exhibited large circadian rhythms of Tb, with maximum active-phase and minimum rest-phase Tb (ρTbmin) values of 42.3 ± 0.1 °C and 37.7 ± 0.6 °C, respectively, in Acacia Pied Barbets (n = 3) and 42.5 ± 0.4 °C and 37.0 ± 0.6 °C, respectively, in Crested Barbets (n = 5). Neither species exhibited any indication of torpor, despite being subjected to a food restriction treatment that is known to elicit torpor in other taxa. Instead, restricted feeding resulted in small but significant increases in the amplitude of circadian Tb rhythms, with ρTbmin ...
TL;DR: Results are broadly consistent with results from studies of other montane bird communities in Africa, which suggest that bird species endemic to Afromontane forests often achieve densities comparable with those of widespread, ecologically similar species, and may thus avoid the ‘double jeopardy’ of small range size and low population density.
Abstract: Biogeographical theory predicts that restricted-range species should typically occur at lower densities than ecologically similar, but geographically widespread species. Exceptions may arise where endemics occupy distinctive habitats, in which they are capable of reaching higher densities than their more widespread competitors. This paper describes the habitat requirements and abundance of a sample of insectivores in Bwindi Impenetrable Forest, part of the Albertine Rift mountains Endemic Bird Area. The altitude ranges, habitat preferences, foraging niches and densities of five Albertine Rift endemics from the genera Phylloscopus, Apalis, Batis and Parus were compared with those of their congeners, or with ecologically similar species. The five endemics were associated with ridgetop forest, steeply sloping ground and a sparse understorey or field layer. They foraged within a narrower height range and used a wider range of substrates than their partner species, but showed no significant differences with re...
TL;DR: In this paper, roadside counts of Pied Crows were made in Madagascar and Cameroon to search for preferred biotopes among natural reserves, artificial pastures, cultivations and towns, while roadside counts in Botswana and Kenya served to compare the Pied Crow and the Somali Crow Corvus edithae, a species probably more similar to common ancestors, in terms of their association with wild and domestic ungulates.
Abstract: The frequently reported close association between the Pied Crow and man suggests a possible explanation for the crow’s wide distribution throughout sub-Saharan Africa, but the mode and origin of this association have received little attention. In the present study, roadside counts of Pied Crows were made in Madagascar and Cameroon to search for preferred biotopes among natural reserves, artificial pastures, cultivations and towns, while roadside counts in Botswana and Kenya served to compare the Pied Crow and the Somali Crow Corvus edithae , a species probably more similar to common ancestors, in terms of their association with wild and domestic ungulates. The occurrence of the sympatric Cape Crow Corvus capensis , assumed to be a less human-dependent species, was also taken into consideration for the association with ungulates. Pied Crow biotope preference was similar in both Madagascar and Cameroon and the combined data showed a significant preference for artificial pasture over cultivation and artificial pasture over natural reserve, and the preference for artificial pasture over town was near to significance. The combined data of the Pied Crow in Botswana and the Somali Crow in Kenya showed a significant preference for domestic ungulates. However, this preference may have been weaker in Kenya, the Somali Crow being rather similar to the Cape Crow in this respect. The Pied and Somali Crows may have diverged somewhere around Ethiopia and the Pied Crow may have expanded its range by following the environmental changes made by ungulate-raising people, who created new savanna-like biotopes. OSTRICH 2010, 81(3): 243–246
TL;DR: In this article, the authors measured relative use of two contiguous forest blocks in Salonga National Park, one patch of primary forest and another of secondary forest that has been regenerating for over 30 years.
Abstract: The Congo Peafowl Afropavo congensis is a little-known species endemic to the Democratic Republic of Congo. A central question in assessing its conservation status is the degree to which it uses secondary forest. Here, we measure relative use of two contiguous forest blocks in Salonga National Park, one patch of primary forest and another of secondary forest that has been regenerating for over 30 years. We searched for Congo Peafowl using systematic surveys along a transect grid, and exhaustive searching of smaller subsections of habitat for secondary signs of peafowl presence (feathers and droppings). Detections of secondary signs of peafowl presence were significantly more frequent in secondary than in primary forest, and 19 of the 31 sightings of birds were in secondary forest. Microhabitats used by the birds differed between forest types, with those in secondary forest being closer to the nearest watercourse, having fewer large trees, and lower plant species richness. In addition, fewer taxonomic groups were found in peafowl droppings collected in secondary forest. Overall, our results demonstrate that old regenerating forest is heavily used by Congo Peafowl at least in this area. Secondary habitats must therefore be considered when planning for the conservation of this species, particularly where regenerating forest fragments might connect larger blocks of habitat.
TL;DR: The author and illustrator explain the process that led to the creation of this book, which was originally written as a monograph for teachers and then edited by the author and turned into a book for children.
Abstract: 2009, Lynx Edicions, Barcelona, Spain 292 pp, hardcover, 40.5 cm × 28 cm, including more than 80 colour and black and white illustrations ISBN 978-84-96553-51-4. Price €100
TL;DR: The number of active colonial waterbird nests at a series of four small constructed wetlands in Cape Town was counted monthly from 1999 to 2008 as discussed by the authors, in total 491 pairs belonging to 11 waterbird species were involved.
Abstract: Understanding breeding site preferences is important for management of colonial waterbirds. The number of active colonial waterbird nests at a series of four small constructed wetlands in Cape Town was counted monthly from 1999 to 2008. In total 491 pairs belonging to 11 waterbird species were involved. Between 1997 and 2004 a number of different artificial structures were used to attract colonial waterbirds to breed at one of the constructed wetlands. The changes in use of the different artificial structures, and of natural reedbeds, for nesting revealed the site preferences of different waterbird species. Structures that simulated flooded dead trees were most successful in attracting breeding waterbirds. Reedbeds were used for nesting when the number of such artificial structures was reduced. When the reedbeds were removed some birds returned to the artificial structures, whereas others moved to a more distant wetland. Some species were pioneers that provided public information about safety from predati...
TL;DR: The contrasts and lack of convergence are surprising, and suggest that these two species are not as closely related as their current congeneric status implies, and are supported by recent molecular studies that place the African and South American Caprimulgus species in different well-supported clades.
Abstract: The Freckled Nightjar Caprimulgus tristigma and the Blackish Nightjar C. nigrescens are widespread and common within their rupicolous habitat, in the Afrotropics and Neotropics respectively, and may therefore be considered as successful in their adaptation to this habitat, a niche that has not been exploited by any other nightjar species. However, apart from a plumage pattern that matches a rocky substrate, their known life histories provide no common factors to explain this adaptive success. The factors that they do share are common to most other nightjars. While they nest and roost on rocks, their breeding biology is remarkably different. The contrasts and lack of convergence are surprising, and suggest that these two species are not as closely related as their current congeneric status implies. This is supported by recent molecular studies that place the African and South American Caprimulgus species in different well-supported clades.
TL;DR: The Damara Tern Sterna balaenarum is a small coastal-nesting seabird that breeds in the Namib Desert, with a stronghold in Namibia as mentioned in this paper.
Abstract: The Damara Tern Sterna balaenarum is a small coastal-nesting seabird that breeds in the Namib Desert, with a stronghold in Namibia. About 125 pairs are known from scattered localities in South Africa, and there are suggestions that it breeds in the northern end of the Namib in Angola. During a three-day survey in southern Angola in January 2009, from Tombua in the north to the Cunene River mouth in the south (a distance of 197 km), 573 Damara Terns, of which 7.5% were fledglings, were recorded in three main concentrations: two in the Baia dos Tigres region, and one 30 km north of the Cunene River mouth. A breeding colony was located at the southern site containing a minimum of six nests with single eggs (5) or a recently hatched chick (1). This represents the first known breeding record for Damara Terns in Angola and is a minimum estimate of the true numbers. Other shorebirds encountered on the survey included the first record of European Oystercatcher Haematopus ostralegus and the second record of Swift ...
TL;DR: In this article, the authors conducted an aerial survey of Shoebills in the Bangweulu Swamps of north-eastern Zambia using a microlight aircraft in July 2006, and used strip transect methodology to estimate population size.
Abstract: The Shoebill Balaeniceps rex is a threatened bird of inaccessible papyrus swamps in central and eastern Africa, and is thus difficult to census. We conducted an aerial survey of Shoebills in the Bangweulu Swamps of north-eastern Zambia using a microlight aircraft in July 2006, and used strip transect methodology to estimate population size. We then applied maximum entropy modelling to satellite images to produce a quantitative map of the likelihood of habitat being suitable (occupied), based on the location of Shoebill sightings. Population size was then re-estimated based on the extent of potentially suitable habitat, which covered 37% of the swamp. Our most conservative mean population size estimate of 1 296 individuals is 550% higher than previous estimates. We suggest that previous estimates may have been underestimates. Our study provides the first estimate of the extent of potentially suitable habitat and an estimate of the population size of Shoebills for the entire swamp. Our analysis of potential habitat suitability can be used to guide future Shoebill surveys, and our methodology can be applied to other little known and inaccessible sites to improve estimates of population size continent-wide. OSTRICH 2010, 81(1): 25–30
TL;DR: Marabou Storks appear to be slower growing than expected for the Ciconiidae, the taxonomic family to which they belong, with chicks at late nests having slower growth, consistent with a decline in food availability.
Abstract: The nesting success of Marabou Storks Leptoptilos crumeniferus breeding in north-eastern Swaziland is closely associated with rainfall, with nests started late in the season exposed to higher rainfall and showing lower success. This may be related to lower food intake and slower growth of the chicks. This study set out to determine whether hatching date and sequence of laying affected the growth rate of chicks. Chicks were also sexed, as Marabou Storks show sexual size dimorphism—males are on average 20% larger—and this trait is often associated with differing patterns of growth between sexes. Nestlings were measured weekly from hatching until they either died or fledged. Nestling development is described in detail and photographs of differentaged chicks are presented. The nestling period was significantly shorter for female chicks, at 94 d, than for male chicks at 104 d. Male and female chicks differed in growth rate and asymptote for both mass and wing length. Unusually, females showed higher instantaneous growth rates for much of the nestling period. Chicks surpassed adult mass before fledging. Date of hatching had an effect on growth rates, with chicks at late nests having slower growth, consistent with a decline in food availability. Marabou Storks appear to be slower growing than expected for the Ciconiidae, the taxonomic family to which they belong. OSTRICH 2010, 81(2): 85–91
TL;DR: It is suggested that subsampling non-moulting birds such that they occur in the expected proportion to actively moultting birds, based on the duration of moult, provides the best estimates of moulting.
Abstract: During the analysis of moult records from the SAFRING database it was found that for some datasets the records were not evenly distributed temporally and the proportion of moulting to non-moulting birds was not what would be expected from random sampling. In an attempt to balance these data, the records of non-moulting birds were subsampled with different sample sizes prior to moult regression analysis, and the resulting moult estimates were then compared. The results suggest that subsampling non-moulting birds such that they occur in the expected proportion to actively moulting birds, based on the duration of moult, provides the best estimates of moult. OSTRICH 2010, 81(3): 265–268
TL;DR: Thirty-five species of birds with known primary feather masses were divided into four wing-shape groups, and a feather mass index was built for each group, and comparisons were made between estimates of moult parameters using the moult index with those using the known primary feathers.
Abstract: During the moult of primary wing feathers in birds it is likely that new feather material is being produced at an approximately constant rate if the energetic requirements of the birds are met. In moult regression analyses it is, therefore, desirable to transform moult measurements into a variable based on the amount of new feather material produced because of its linear properties. This can be achieved if the mass of each primary feather is known, and used as a weighting factor in a moult index. These primary feather masses would have to be known for every species being analysed. As an alternative, it is here tested if feather mass indices may be sufficient replacements for species-specific feather masses. Thirty-five species of birds with known primary feather masses were divided into four wing-shape groups, and a feather mass index was built for each group. Within each group, comparisons were made between estimates of moult parameters using the moult index with those using the known primary feather mas...
TL;DR: In this article, the Pink-backed Pelican Pelecanus rufescens and the Great White Pelican P. onocrotalus were found to be highly variable at the main locality, Lake St Lucia in KwaZulu-Natal, South Africa.
Abstract: KwaZulu-Natal (KZN), South Africa, is the most southerly area in Africa in which the Pink-backed Pelican Pelecanus rufescens breeds. This area also boasts the most southerly breeding colony on the eastern seaboard of Africa for the Great White Pelican P. onocrotalus. Considerable amounts of data relating to the distribution and numbers of these two species in north-eastern KZN have been collected in a variety of ways by a number of people. These data were collated to estimate the distribution and status of the two pelican species and to evaluate any trends. There is no evidence of contraction or expansion in the distribution of either species. Numbers in south-eastern Africa are estimated to be 6 000–9 000 for the Great White Pelican and 600–900 for the Pink-backed Pelican. Numbers of both species were highly variable at the main locality, Lake St Lucia. For their long-term conservation it is necessary to take into account that neither population is restricted to the study area and that there are fluctuat...