BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
This paper quantifies the density and the total number of granivorous and insectivorous ground-foraging birds, whether Afro-Palearctic migrants or Afro-tropical residents, in the transition zone between the arid Sahara and the humid Guinea zone. Situated between 17°W and 42°E and between 7°N and 22°N, this is an area covering 10 million km 2 . The study took place during the northern winter, between 20 November and 10 March (thus covering much of the long dry season) from 2011 up to and including 2019. Using a stratified random sampling regime, we counted birds at 1901 sites of 4.5 ha in area. We present background information about the study region, with maps showing variation in elevation, rainfall, woody cover, land use and human population density. The bird counts were converted into average densities for 43 bird species in 150 grid cells of 1° latitude × 1° longitude. The distribution of the various bird species was predominantly related to annual rainfall, but because woody cover increases with rainfall, species' preferences for arid or more humid zones were partly influenced by an overall preference for open or more wooded landscapes. Bird species such as larks and Tawny Pipit Anthus campestris, even when rainfall was accounted for, selected comparatively open landscapes, whereas species feeding on the ground near trees or using them as perches (e.g. sparrows, finches, shrikes, Tree Pipit Anthus trivialis) preferred relatively more enclosed environments. To estimate total population size, the 150 grid cells were assembled into eleven rainfall categories (per 100 mm rainfall) and six longitudinal bands. To assess the reliability of these estimations, population sizes were calculated separately on the 1901 study sites split in two halves. The estimated population sizes were precise for migrants, especially for insectivores (7% deviation for the split-half estimates), but less precise for residents (22-28% deviation). Most ground-foraging birds were granivorous (at least in the dry season), their total number being estimated at 4000 million residents and 133 million migrants, residents being 30 times as abundant as migrants. Ground-foraging insectivores were less numerous, the total estimated being 920 million birds, of which 694 million were residents and 221 million migrants, the ratio residents/ migrants being an order of magnitude smaller than in granivores. The three most abundant granivorous residents were Red-cheeked Cordon-bleu Uraeginthus bengalus (467 million), Sudan Golden Sparrow Passer luteus (375 million birds) and Red-billed Quelea Quelea quelea (311 million). The Greater Short-toed Lark Calandrella brachydactyla (126 million) was the only common granivorous migrant. The most common insectivorous ground-foraging bird was a resident (Greater Blue-eared Starling Lamprotornis chalybaeus; 100 million), and more commonly encountered than all the ground-foraging insectivorous migrants such as Isabelline Wheatear Oenanthe isabellina (32 million), Northern Wheatear Oenanthe oenanthe (27 million) and W...
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Eye tracking is a process that allows an observers gaze to be determined in real time by measuring their eye movements. Recent work has examined the possibility of using gaze control as an alternative input modality in interactive applications. Alternative means of interaction are especially important for disabled users for whom traditional techniques, such as mouse and keyboard, may not be feasible. This paper proposes a novel combination of gaze and voice commands as a means of hands free interaction in a paint style program. A drawing application is implemented which is controllable by input from gaze and voice. Voice commands are used to activate drawing which allow gaze to be used only for positioning the cursor. In previous work gaze has also been used to activate drawing using dwell time. The drawing application is evaluated using subjective responses from participant user trials. The main result indicates that although gaze and voice offered less control that traditional input devices, the participants reported that it was more enjoyable.
No abstract
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
The Sahel shows a tremendous change in landscape as one travels from north to south, from the bare Sahara with scattered scrub and small, spiny trees to dense Guinea forests. The aim of the present paper is to show the distribution of arboreal bird species south of the Sahara and to estimate their total number between the Atlantic Ocean and the Red Sea (a distance of 6000 km) in a 1600 km wide band. The paper is complementary to the one describing the distribution of groundforaging birds (Zwarts et al. 2023a). Together they form the descriptive basis for attempts to explain the observed bird distributions and why so many migratory -and African -bird species are in decline. METHODS Study sitesThe data for this particular study were collected between 2011 and 2019 during the dry season (20 November -10 March), in sites (usually 4.5 ha; a triangle with three sides of 300 × 50 m) situated
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