Movement ecology and fisheries bycatch risk of albatross and large petrel species from Bird Island, South Georgia
Recording animal movements is essential for understanding the distribution of species over time, with far-reaching consequences for fitness, population dynamics and conservation. Oceanic seabirds are some of the most mobile and threatened species on Earth, mainly because of incidental mortality (byc...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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University of Cambridge
2021
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| Online Access: | https://www.repository.cam.ac.uk/handle/1810/324761 https://doi.org/10.17863/CAM.72214 |
| Summary: | Recording animal movements is essential for understanding the distribution of species over time, with far-reaching consequences for fitness, population dynamics and conservation. Oceanic seabirds are some of the most mobile and threatened species on Earth, mainly because of incidental mortality (bycatch) in fisheries. Tracking these birds has improved our knowledge of how the environment and individual traits shape specific foraging and migratory strategies; however, this research is biased towards adult life-stages, which are easier to track. In particular, juveniles remain understudied, even though they are likely to differ in their critical habitats and overlap with fisheries, and hence bycatch risk, with implications for population trajectories. In this thesis, I capitalize on recent advances in tracking technology and the wealth of data collected on threatened albatross and large petrel species breeding at Bird Island, South Georgia, to investigate variation in spatial ecology and fisheries bycatch risk across multiple life-stages and species. In Chapter 1, I introduce the main topics of this thesis. In Chapters 2-4, I investigate how wind and resource availability shape divergent movement patterns between juveniles and adult life-stages, and identify age-specific bycatch risk. As high juvenile mortality is likely to result in an ageing population, in Chapter 5 I examine senescence in foraging behaviour, and consider the ramifications for population recovery. In Chapter 6, I then assess the effectiveness of existing fisheries bycatch mitigation measures by investigating the diving capabilities of the most bycaught species in the Southern Ocean. Finally, I conclude with a general discussion summarizing my main findings and suggesting future work. Overall, my results provide new insight into the capacity and motivation for movement in wide-ranging animals; highlighting the diversity of extrinsic and intrinsic processes shaping movements over the lifespans of individuals, and with implications for focusing ... |
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