| 1. |
- Cantlay, Jennifer C., et al.
(författare)
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Binocular vision and foraging in ducks, geese and swans (Anatidae)
- 2023
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - 0962-8452. ; 290:2006
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Tidskriftsartikel (refereegranskat)abstract
- Wide variation in visual field configuration across avian species is hypothesized to be driven primarily by foraging ecology and predator detection. While some studies of selected taxa have identified relationships between foraging ecology and binocular field characteristics in particular species, few have accounted for the relevance of shared ancestry. We conducted a large-scale, comparative analysis across 39 Anatidae species to investigate the relationship between the foraging ecology traits of diet or behaviour and binocular field parameters, while controlling for phylogeny. We used phylogenetic models to examine correlations between traits and binocular field characteristics, using unidimensional and morphometric approaches. We found that foraging behaviour influenced three parameters of binocular field size: maximum binocular field width, vertical binocular field extent, and angular separation between the eye-bill projection and the direction of maximum binocular field width. Foraging behaviour and body mass each influenced two descriptors of binocular field shape. Phylogenetic relatedness had minimal influence on binocular field size and shape, apart from vertical binocular field extent. Binocular field differences are associated with specific foraging behaviours, as related to the perceptual challenges of obtaining different food items from aquatic and terrestrial environments.
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| 2. |
- Garde, Baptiste, et al.
(författare)
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Fine-scale changes in speed and altitude suggest protean movements in homing pigeon flights
- 2021
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Ingår i: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 8:5
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Tidskriftsartikel (refereegranskat)abstract
- The power curve provides a basis for predicting adjustments that animals make in flight speed, for example in relation to wind, distance, habitat foraging quality and objective. However, relatively few studies have examined how animals respond to the landscape below them, which could affect speed and power allocation through modifications in climb rate and perceived predation risk. We equipped homing pigeons (Columba livia) with high-frequency loggers to examine how flight speed, and hence effort, varies in relation to topography and land cover. Pigeons showed mixed evidence for an energy-saving strategy, as they minimized climb rates by starting their ascent ahead of hills, but selected rapid speeds in their ascents. Birds did not modify their speed substantially in relation to land cover, but used higher speeds during descending flight, highlighting the importance of considering the rate of change in altitude before estimating power use from speed. Finally, we document an unexpected variability in speed and altitude over fine scales; a source of substantial energetic inefficiency. We suggest this may be a form of protean behaviour adopted to reduce predation risk when flocking is not an option, and that such a strategy could be widespread.
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| 3. |
- Portugal, Steven J., et al.
(författare)
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Anomalous binocular vision in African Harrier-Hawks
- 2023
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Ingår i: Current Biology. - 0960-9822. ; 33:21, s. 1142-1143
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Tidskriftsartikel (refereegranskat)abstract
- An animal's visual field is the three-dimensional space around its head from which it can extract visual information at any instant1. Bird visual fields vary markedly between species, and this variation is likely to be driven primarily by foraging ecology1,2,3. The binocular visual field is the region in which the visual fields of the two eyes overlap; thus, objects in the binocular field are imaged by both eyes simultaneously. The binocular field plays a pivotal role in the detection of symmetrical optic flow-fields, providing almost instantaneous information on the direction of travel and the time to contact a target towards which the head or feet is travelling; thus, information from the binocular field is crucial in guiding key foraging behaviours2,3. Here, we demonstrate an unusual visual field and binocular extent above the head in African Harrier-Hawks, also known as Gymnogenes (Polyboroides typus) compared to 18 other members of the Accipitridae4,5. We argue that the observed visual field can be attributed to the unusual and specific foraging behaviour of African Harrier-Hawks.
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| 4. |
- Potier, Simon, et al.
(författare)
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Binocular field configuration in owls : The role of foraging ecology
- 2023
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - 0962-8452. ; 290:2009
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Tidskriftsartikel (refereegranskat)abstract
- The binocular field of vision differs widely in birds depending on ecological traits such as foraging. Owls (Strigiformes) have been considered to have a unique binocular field, but whether it is related to foraging has remained unknown. While taking into account allometry and phylogeny, we hypothesized that both daily activity cycle and diet determine the size and shape of the binocular field in owls. Here, we compared the binocular field configuration of 23 species of owls. While we found no effect of allometry and phylogeny, ecological traits strongly influence the binocular field shape and size. Binocular field shape of owls significantly differed from that of diurnal raptors. Among owls, binocular field shape was relatively conserved, but binocular field size differed among species depending on ecological traits, with larger binocular fields in species living in dense habitat and foraging on invertebrates. Our results suggest that (i) binocular field shape is associated with the time of foraging in the daily cycle (owls versus diurnal raptors) and (ii) that binocular field size differs between closely related owl species even though the general shape is conserved, possibly because the field of view is partially restricted by feathers, in a trade-off with auditory localization.
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