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- Krishnan, Krishnamoorthy, et al.
(författare)
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The role of wingbeat frequency and amplitude in flight power
- 2022
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Ingår i: Journal of the Royal Society Interface. - : The Royal Society. - 1742-5689 .- 1742-5662. ; 19:193
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Tidskriftsartikel (refereegranskat)abstract
- Body-mounted accelerometers provide a new prospect for estimating power use in flying birds, as the signal varies with the two major kinematic determinants of aerodynamic power: wingbeat frequency and amplitude. Yet wingbeat frequency is sometimes used as a proxy for power output in isolation. There is, therefore, a need to understand which kinematic parameter birds vary and whether this is predicted by flight mode (e.g. accelerating, ascending/descending flight), speed or morphology. We investigate this using high-frequency acceleration data from (i) 14 species flying in the wild, (ii) two species flying in controlled conditions in a wind tunnel and (iii) a review of experimental and field studies. While wingbeat frequency and amplitude were positively correlated, R 2 values were generally low, supporting the idea that parameters can vary independently. Indeed, birds were more likely to modulate wingbeat amplitude for more energy-demanding flight modes, including climbing and take-off. Nonetheless, the striking variability, even within species and flight types, highlights the complexity of describing the kinematic relationships, which appear sensitive to both the biological and physical context. Notwithstanding this, acceleration metrics that incorporate both kinematic parameters should be more robust proxies for power than wingbeat frequency alone.
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| 2. |
- Bouwman, Hindrik, et al.
(författare)
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The flip-or-flop boutique: Marine debris on the shores of St Brandon’s Rock, an isolated tropical atoll in the Indian Ocean
- 2016
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 114, s. 58-64
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Tidskriftsartikel (refereegranskat)abstract
- Isolated coral atolls are not immune from marine debris accumulation. We identified Southeast Asia, the Indian sub-continent, and the countries on the Arabian Sea as most probable source areas of 50 000 items on the shores of St. Brandon’s Rock (SBR), Indian Ocean. 79% of the debris was plastics. Flip-flops, energy drink bottles, and compact fluorescent lights (CFLs) were notable item types. The density of debris (0.74 m-1 shore length) is comparable to similar islands but less than mainland sites. Intact CFLs suggests product-facilitated long-range transport of mercury. We suspect that aggregated marine debris, scavenged by the islands from currents and gyres, could re-concentrate pollutants. SBR islets accumulated debris types in different proportions suggesting that many factors act variably on different debris types. Regular cleaning of selected islets will take care of most of the accumulated debris and may improve the ecology and tourism potential. However, arrangements and logistics require more study.
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| 3. |
- van der Schyff, Veronica, et al.
(författare)
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Persistent organic pollutants in sea bird eggs from the Indian Oceans Mascarene Basin
- 2021
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Ingår i: Science of the Total Environment. - : ELSEVIER. - 0048-9697 .- 1879-1026. ; 771
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Tidskriftsartikel (refereegranskat)abstract
- We report the concentrations of persistent organic pollutants (POPs) in seabird eggs from St. Brandons Atoll, a tropical island system in the western Indian Ocean. Ten eggs each of sooty terns (Onychoprion juscatus), fairy terns (Gygis alba), and common noddies (Anous stolidus) were collected from the atoll. For a terrestrial reference, we analysed three feral chicken (Gallus gallus domesticus) eggs from the same location. Sooty tern eggs contained the highest mean concentrations of three chemical classes: Sigma CHL3 (0.21 ng/g wm; wet mass), Sigma PCB10 (1.5 ng/g wm), and Sigma PBDE6 (1.1 ng/g wm). Fairy tern eggs contained the highest mean concentrations of HCB (0.68 ng/g wm) and Sigma CHB5 (0.83 ng/g wm). The chicken eggs contained the highest mean concentrations of Sigma DDT3 (2.6 ng/g wm), while common noddy eggs contained the highest mean concentrations of Sigma HCH2 (0.5 ng/g wm). We surmise that the differences in chemical composition between species reflect different pollutant compositions in prey from the birds different foraging ranges. The sooty terns foraging offshore contained higher POPs concentrations than the nearshore-foraging common noddies. Fairy tern eggs contained intermediate concentrations, commensurate with their intermediate foraging. Inter-island differences in contaminant concentrations were seen between eggs of the common noddies from St. Brandons Atoll and Rodrigues Island, 520 km to the south-east. Concentrations of contaminants found in this study were lower than values quantified by other studies, making St. Brandons Atoll an ideal reference site to monitor background concentrations of POPs in the tropical Indian Ocean. (C) 2021 Elsevier B.V. All rights reserved.
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