Robin M. Little
Other affiliations: University of Cape Town
Bio: Robin M. Little is an academic researcher from Percy FitzPatrick Institute of African Ornithology. The author has contributed to research in topics: Namaqua sandgrouse & Pterocles. The author has an hindex of 11, co-authored 27 publications receiving 397 citations. Previous affiliations of Robin M. Little include University of Cape Town.
TL;DR: In this article, the authors examined the relationship between waterbird use and habitat characteristics of farm ponds and concluded that the high number of farms in the transformed habitat matrix of the Western Cape plays an important role in conserving waterbirds.
Abstract: Natural freshwater wetlands are among the most threatened habitats on Earth. Effective wetland biodiversity conservation can not, however, be evaluated without fully understanding the roles of artificial waterbodies as refuges for water-dependent plants and animals. Waterbird assemblages were examined on 59 farm ponds in the Elgin and Caledon districts of the Western Cape, South Africa. This study examines the relationship between waterbird use and habitat characteristics of farm ponds. Patterns of temporal and spatial variation of waterbird species richness and abundance were quantified in relation to the habitat characteristics of each pond. Cluster analysis and multiple regression analyses identified surface area of the farm ponds as an important variable determining the presence and abundance of many waterbird species. Structural diversity in terms of vegetation in and around the ponds was especially important in determining their usage by waterbirds. These variables were evaluated in terms of creating a mosaic of habitat types (by varying vegetation structure and pond topography), which may be a useful way to enhance waterbird diversity at farm ponds. This study concludes that the high number of farm ponds in the transformed habitat matrix of the Western Cape plays an important role in conserving waterbirds.
TL;DR: Intra-clutch diversity in pigment cover the number of wreathed eggs, the dominant pigment pattern, and the overall shade of the clutch did not affect clutch survival, but clutches exhibiting diversity in background colout, pigment pattern or pigment intensity between eggs survived significantly better than clutches whose eggs were uniform for these variables suggesting there is some selection for clutch crypsis through visual diversity.
Abstract: Nest survival can, among a variety of factors, depend on nest-site complexity and concealment, and clutch crypsis. Nest-site selection by Namaqua Sandgrouse Pterocles namaqua was strongly non-random. Nests were sited within a local concentration of objects, most of them less than 15 cm high and concentrated within 30 cm of the nest centre. Nest-to-object orientation was random, indicating that the nest was sited close to objects neither for shade nor shelter from prevailing winds. A stepwise logistic regression analysis, using nine different object type, height and distance category totals as variables of nest-site complexity and concealment, found no effect of these variables on nest fate (survival vs mammal predation). A random-walk model simulating the foraging movements of a small mammal predator raised the possibility that the high level of nest predation suffered by Namaqua Sandgrouse was largely incidental (i.e. random). Namaqua Sandgrouse eggs were highly variable in appearance, but intra-clutch variability was less than that between clutches of different individuals. Intra-clutch diversity in pigment cover the number of wreathed eggs, the dominant pigment pattern, and the overall shade of the clutch (light/dark) did not affect clutch survival. However, clutches exhibiting diversity in background colout, pigment pattern or pigment intensity between eggs survived significantly better than clutches whose eggs were uniform for these variables suggesting there is some selection for clutch crypsis through visual diversity.
TL;DR: Blood smears from 97 sandgrouse and 20 Sociable Weavers Philetarius socius collected in the semi-arid Northern Cape Province, South Africa were examined and it is suggested that these environments are generally free of avian Haematozoa.
Abstract: Blood smears from 97 sandgrouse (64 Namaqua Sandgrouse Pterocles namaqua , 28 Burchell's Sandgrouse P. burchelli and five Doublebanded Sandgrouse P. bicinctus ) and from 20 Sociable Weavers Philetarius socius collected in the semi-arid Northern Cape Province, South Africa were examined. No blood parasites were observed in any of the smears examined. Because of the scarcity of breeding habitats for the vectors of avian Haematozoa in arid and semi-arid regions of southern Africa, it is suggested that these environments are generally free of avian Haematozoa.
TL;DR: Results from the southern hemisphere subtropics support the findings of limited north-temperate studies that largely mammalian nest predation does not increase after researcher disturbance.
Abstract: We examined whether regular researcher visits affected egg hatchability or nest predation for three ground-nesting bird species that incur high levels of nest predation, primarily by small mammals. Frequently visited finch-lark (Eremopterix verticalis and E. australis) nests suffered similar predation to nests visited infrequently, suggesting that regular visits had no additive effects on nest survival. A comparison of finch-lark nests visited for the second time either one or two days after the first visit found that predation during the first 24 h (7.4%) was lower than predation during the second 24-h period (9.9%), suggesting that the act of visiting a nest did not increase the risk of predation. Daily predation rates on Namaqua Sandgrouse (Pterocles namaqua) and finch-lark nests showed no observable trend with an increasing number of visits over time, indicating that frequent visits had no cumulative effect on predation probabilities. Nests of both Grey-backed Finch-lark (E. verticalis) and B...
TL;DR: The greywing's breeding season is more consistently positively correlated with measures of environmental variation in the summer rainfall region than in the winter rainfall region and flushed single birds were the best indicators of nesting sites.
Abstract: We studied the breeding biology of the greywing francolin Francolinus africanus on the Stormberg Plateau of the eastern Cape Province, South Africa during 1988–1991. Timing of breeding, nesting behaviour, clutch size, egg size, and clutch survival rates were recorded and compared with published and unpublished information from Natal, the eastern Orange Free State and south-western Cape Province. The greywing breeds during the austral summer throughout its range, with peak laying activity during August-November. However, the nesting period is contracted in the south-western Cape, where it starts about one month earlier and ends three months earlier than in the eastern Orange Free State and the eastern Cape, where laying was recorded from August to March. The greywing's breeding season is more consistently positively correlated with measures of environmental variation in the summer rainfall region than in the winter rainfall region. Flushed single birds were the best indicators of nesting sites. Clutches we...
TL;DR: It is shown that ecological effects of habitat heterogeneity may vary considerably between species groups depending on whether structural attributes are perceived as heterogeneity or fragmentation, and possible effects may also vary relative to the structural variable measured.
Abstract: Aim In a selected literature survey we reviewed studies on the habitat heterogeneity–animal species diversity relationship and evaluated whether there are uncertainties and biases in its empirical support. Location World-wide. Methods We reviewed 85 publications for the period 1960–2003. We screened each publication for terms that were used to define habitat heterogeneity, the animal species group and ecosystem studied, the definition of the structural variable, the measurement of vegetation structure and the temporal and spatial scale of the study. Main conclusions The majority of studies found a positive correlation between habitat heterogeneity/diversity and animal species diversity. However, empirical support for this relationship is drastically biased towards studies of vertebrates and habitats under anthropogenic influence. In this paper, we show that ecological effects of habitat heterogeneity may vary considerably between species groups depending on whether structural attributes are perceived as heterogeneity or fragmentation. Possible effects may also vary relative to the structural variable measured. Based upon this, we introduce a classification framework that may be used for across-studies comparisons. Moreover, the effect of habitat heterogeneity for one species group may differ in relation to the spatial scale. In several studies, however, different species groups are closely linked to ‘keystone structures’ that determine animal species diversity by their presence. Detecting crucial keystone structures of the vegetation has profound implications for nature conservation and biodiversity management.
TL;DR: In this paper, the relative contribution of gene flow to population genetic differentiation is analyzed using comparative methods, such as FST, heterozygosity and Nei's D, and the available literature was searched for all groups that meet these criteria.
Abstract: The accuracy of gene flow estimates is unknown in most natural populations because direct estimates of dispersal are often not possible. These estimates can be highly imprecise or even biased because population genetic structure reflects more than a simple balance between genetic drift and gene flow. Most of the models used to estimate gene flow also assume very simple patterns of movement. As a result, multiple interpretations of population structure involving contemporary gene flow, departures from equilibrium, and other factors are almost always possible. One way to isolate the relative contribution of gene flow to population genetic differentiation is to utilize comparative methods. Population genetic statistics such as FST, heterozygosity and Nei's D can be compared between species with differing dispersal abilities if these species are otherwise phylogenetically, geographically and demographically comparable. Accordingly, the available literature was searched for all groups that meet these criteria ...
01 Jan 1969
TL;DR: The Washington Biological Society has just published a reprint at the price of one dollar of the Code ofworms, with the permission of the Commission.
Abstract: DURING this year I have so often been asked how this Code could be obtained that I hasten, with your permission, to announce that the Washington Biological Society has just published a reprint at the price of one dollar. Prof. C. W. Stiles, secretary to the Commission, says: “I would suggest that, if your colleagues wish copies, it would expedite matters to order a number at once”. The address of the Society is at the Bureau of Entomology, Washington, D.C., U.S.A.