The effects of introduced mice on seabirds breeding at sub-Antarctic Islands
Seabirds play keystone roles as apex predators in marine ecosystems and also influence the ecology of terrestrial ecosystems where they breed. Seabirds are among the most threatened group of birds - almost half of all seabird species are known or suspected to be experiencing population declines with...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Faculty of Science
2018
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| Online Access: | http://hdl.handle.net/11427/30098 https://open.uct.ac.za/bitstream/11427/30098/1/thesis_sci_2018_dilley_ben_j.pdf |
| Summary: | Seabirds play keystone roles as apex predators in marine ecosystems and also influence the ecology of terrestrial ecosystems where they breed. Seabirds are among the most threatened group of birds - almost half of all seabird species are known or suspected to be experiencing population declines with 97 (28%) of the 346 species currently classed as globally threatened and at risk of extinction. Introduced predators at oceanic islands where many seabirds breed account for the largest proportion of population declines, more so than incidental fisheries bycatch or degradation of their breeding habitats. Since few oceanic islands have escaped invasion, the problem is widespread, with the prime culprits being introduced cats Felis catus, rats Rattus spp. and house mice Mus musculus which depredate adult birds, chicks and eggs. Rats were widely introduced to thousands of islands and their catastrophic effects on seabird populations have been well documented. Mice are estimated to have invaded more oceanic islands than any other alien predator, but until fairly recently they were considered to have little impact on seabird populations. This thesis focuses on seabirds breeding at two large oceanic islands - Marion Island (293 km2 ) in the south Indian Ocean and Gough Island (65 km2 ) in the south central Atlantic Ocean. Both islands have mice as the sole introduced mammal. Of relevance to this study, however, is that the density of burrow-nesting petrels is much higher on Gough Island because Marion Island’s petrel populations were greatly reduced by cats, which were introduced in 1948 and eradicated by 1991. In the early 2000s, researchers on Gough Island identified mouse predation as the most probable cause of the high chick mortality of at least three species of seabirds, including the endemic Tristan albatross Diomedea dabbenena. Further research concluded that mice can be devastating predators of seabirds on islands where they are the sole introduced mammal, because in the absence of competition and predation from ... |
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