Interference competition between introduced black rats and endemic Galápagos rice rats
Replicated field experiments were used to quantify and to describe the mechanism of competition between the introduced black rat Rattus rattus and the endemic Santiago rice rat Nesoryzomys swarthi on Santiago Island, Galápagos Islands, Ecuador. The removal of R. rattus significantly slowed the rate...
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Ecological Soc Amer
2007
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Online Access: | http://hdl.handle.net/2440/66487 https://doi.org/10.1890/06-1701.1 |
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ftunivadelaidedl:oai:digital.library.adelaide.edu.au:2440/66487 2023-12-24T10:24:28+01:00 Interference competition between introduced black rats and endemic Galápagos rice rats Interference competition between introduced black rats and endemic Galapagos rice rats Harris, D. Macdonald, D. 2007 http://hdl.handle.net/2440/66487 https://doi.org/10.1890/06-1701.1 en eng Ecological Soc Amer Ecology, 2007; 88(9):2330-2344 0012-9658 http://hdl.handle.net/2440/66487 doi:10.1890/06-1701.1 © 2007 by the Ecological Society of America http://dx.doi.org/10.1890/06-1701.1 coexistence encounter interference food supplementation interspecific competition introduced species Mus musculus Nesoryzomys swarthi press experiment Rattus rattus removal experiment Santiago Island Galápagos sex-mediated competition Journal article 2007 ftunivadelaidedl https://doi.org/10.1890/06-1701.1 2023-11-27T23:23:30Z Replicated field experiments were used to quantify and to describe the mechanism of competition between the introduced black rat Rattus rattus and the endemic Santiago rice rat Nesoryzomys swarthi on Santiago Island, Galápagos Islands, Ecuador. The removal of R. rattus significantly slowed the rate of seasonal population decline in N. swarthi. This effect was particularly evident for female, relative to male, N. swarthi and appeared to be driven solely by enhanced immigration; no other fitness or space use parameters were affected. The candidate hypotheses to explain the mechanism of competition were exploitation competition, interference by resource defense, and interference by aggressive encounter. To distinguish between hypotheses, we conducted a replicated resource supplementation experiment with patchy food, scattered food, and no food (control) treatments. The opportunistic R. rattus responded to the extra resources with increased adult immigration and juvenile recruitment, resulting in a significant abundance boost of sevenfold on patchy grids and fourfold on scattered grids. Females increased in body mass, and the breeding season was lengthened. In contrast, there was no change in the abundance of N. swarthi and no obvious benefit to reproduction. Instead, the costs of interference apparently outweighed the benefits of extra food: female N. swarthi increased in mass with supplementary food, but female (relative to male) immigration and residency were repressed on all supplemented areas. This response supported the hypothesis of interference by aggressive encounter, and we were able to rule out the alternative hypotheses. Although periodic population crashes of R. rattus on the arid north coast of Santiago may ameliorate its competitive impact, climate change may tip the balance. Control or eradication of R. rattus should improve future survival prospects for N. swarthi, but wildlife managers must be prepared for the potential eruption of the introduced house mouse Mus musculus, because this species ... Article in Journal/Newspaper Rattus rattus The University of Adelaide: Digital Library Galapagos Ecology 88 9 2330 2344 |
institution |
Open Polar |
collection |
The University of Adelaide: Digital Library |
op_collection_id |
ftunivadelaidedl |
language |
English |
topic |
coexistence encounter interference food supplementation interspecific competition introduced species Mus musculus Nesoryzomys swarthi press experiment Rattus rattus removal experiment Santiago Island Galápagos sex-mediated competition |
spellingShingle |
coexistence encounter interference food supplementation interspecific competition introduced species Mus musculus Nesoryzomys swarthi press experiment Rattus rattus removal experiment Santiago Island Galápagos sex-mediated competition Harris, D. Macdonald, D. Interference competition between introduced black rats and endemic Galápagos rice rats |
topic_facet |
coexistence encounter interference food supplementation interspecific competition introduced species Mus musculus Nesoryzomys swarthi press experiment Rattus rattus removal experiment Santiago Island Galápagos sex-mediated competition |
description |
Replicated field experiments were used to quantify and to describe the mechanism of competition between the introduced black rat Rattus rattus and the endemic Santiago rice rat Nesoryzomys swarthi on Santiago Island, Galápagos Islands, Ecuador. The removal of R. rattus significantly slowed the rate of seasonal population decline in N. swarthi. This effect was particularly evident for female, relative to male, N. swarthi and appeared to be driven solely by enhanced immigration; no other fitness or space use parameters were affected. The candidate hypotheses to explain the mechanism of competition were exploitation competition, interference by resource defense, and interference by aggressive encounter. To distinguish between hypotheses, we conducted a replicated resource supplementation experiment with patchy food, scattered food, and no food (control) treatments. The opportunistic R. rattus responded to the extra resources with increased adult immigration and juvenile recruitment, resulting in a significant abundance boost of sevenfold on patchy grids and fourfold on scattered grids. Females increased in body mass, and the breeding season was lengthened. In contrast, there was no change in the abundance of N. swarthi and no obvious benefit to reproduction. Instead, the costs of interference apparently outweighed the benefits of extra food: female N. swarthi increased in mass with supplementary food, but female (relative to male) immigration and residency were repressed on all supplemented areas. This response supported the hypothesis of interference by aggressive encounter, and we were able to rule out the alternative hypotheses. Although periodic population crashes of R. rattus on the arid north coast of Santiago may ameliorate its competitive impact, climate change may tip the balance. Control or eradication of R. rattus should improve future survival prospects for N. swarthi, but wildlife managers must be prepared for the potential eruption of the introduced house mouse Mus musculus, because this species ... |
format |
Article in Journal/Newspaper |
author |
Harris, D. Macdonald, D. |
author_facet |
Harris, D. Macdonald, D. |
author_sort |
Harris, D. |
title |
Interference competition between introduced black rats and endemic Galápagos rice rats |
title_short |
Interference competition between introduced black rats and endemic Galápagos rice rats |
title_full |
Interference competition between introduced black rats and endemic Galápagos rice rats |
title_fullStr |
Interference competition between introduced black rats and endemic Galápagos rice rats |
title_full_unstemmed |
Interference competition between introduced black rats and endemic Galápagos rice rats |
title_sort |
interference competition between introduced black rats and endemic galápagos rice rats |
publisher |
Ecological Soc Amer |
publishDate |
2007 |
url |
http://hdl.handle.net/2440/66487 https://doi.org/10.1890/06-1701.1 |
geographic |
Galapagos |
geographic_facet |
Galapagos |
genre |
Rattus rattus |
genre_facet |
Rattus rattus |
op_source |
http://dx.doi.org/10.1890/06-1701.1 |
op_relation |
Ecology, 2007; 88(9):2330-2344 0012-9658 http://hdl.handle.net/2440/66487 doi:10.1890/06-1701.1 |
op_rights |
© 2007 by the Ecological Society of America |
op_doi |
https://doi.org/10.1890/06-1701.1 |
container_title |
Ecology |
container_volume |
88 |
container_issue |
9 |
container_start_page |
2330 |
op_container_end_page |
2344 |
_version_ |
1786199271883669504 |