Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand
Ship rat (Rattus rattus) density was assessed by snap-trapping during summer and autumn in eight indigenous forest fragments (mean 5 ha) in rural landscapes of Waikato, a lowland pastoral farming district of the North Island, New Zealand. Four of the eight were fenced and four grazed. In each set of...
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ftunivwaikato:oai:researchcommons.waikato.ac.nz:10289/3879 2023-07-30T04:06:31+02:00 Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand Innes, John G. King, Carolyn M. Bridgman, Lucy Jade Fitzgerald, Neil Arnold, Greg Cox, Neil R. 2010 application/pdf https://hdl.handle.net/10289/3879 en eng New Zealand Ecological Society http://www.nzes.org.nz/nzje/new_issues/NZJEcol34_2_227.pdf New Zealand Journal of Ecology Innes, J., King, C.M., Bridgman, L., Fitzgerald, N., Arnold, G. & Cox, N. (2010). Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand. New Zealand Journal of Ecology, 34(2), 227-232. https://hdl.handle.net/10289/3879 This article has been published in the journal: New Zealand Journal of Ecology. © 2010 New Zealand Ecological Society. Used with permission. fencing isolation predator density rapid indexing Rattus rattus tracking trapping Journal Article 2010 ftunivwaikato 2023-07-11T17:21:52Z Ship rat (Rattus rattus) density was assessed by snap-trapping during summer and autumn in eight indigenous forest fragments (mean 5 ha) in rural landscapes of Waikato, a lowland pastoral farming district of the North Island, New Zealand. Four of the eight were fenced and four grazed. In each set of four, half were connected with hedgerows, gullies or some other vegetative corridor to nearby forest and half were completely isolated. Summer rat density based on the number trapped in the first six nights was higher in fenced (mean 6.5 rats ha–1) than in grazed fragments (mean 0.5 rats ha–1; P = 0.02). Rats were eradicated (no rats caught and no rat footprints recorded for three consecutive nights) from all eight fragments in January–April 2008, but reinvaded within a month; time to eradication averaged 47 nights in fenced and 19 nights in grazed fragments. A second six-night trapping operation in autumn, 1–3 months after eradication, found no effect of fencing (P = 0.73). Connectedness to an adjacent source of immigrants did not influence rat density within a fragment in either season (summer P = 0.25, autumn P = 0.67). An uncalibrated, rapid (one-night) index of ship rat density, using baited tracking tunnels set in a 50 × 50 m grid, showed a promising relationship with the number of rats killed per hectare over the first six nights, up to tracking index values of c. 30% (corresponding to c. 3–5 rats ha–1). The index will enable managers to determine if rat abundance is low enough to achieve conservation benefits. Our results confirm a dilemma for conservation in forest fragments. Fencing protects vegetation, litter and associated ecological processes, but also increases number of ship rats, which destroy seeds, invertebrates and nesting birds. Maximising the biodiversity values of forest fragments therefore requires both fencing and control of ship rats. Article in Journal/Newspaper Rattus rattus The University of Waikato: Research Commons New Zealand |
institution |
Open Polar |
collection |
The University of Waikato: Research Commons |
op_collection_id |
ftunivwaikato |
language |
English |
topic |
fencing isolation predator density rapid indexing Rattus rattus tracking trapping |
spellingShingle |
fencing isolation predator density rapid indexing Rattus rattus tracking trapping Innes, John G. King, Carolyn M. Bridgman, Lucy Jade Fitzgerald, Neil Arnold, Greg Cox, Neil R. Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand |
topic_facet |
fencing isolation predator density rapid indexing Rattus rattus tracking trapping |
description |
Ship rat (Rattus rattus) density was assessed by snap-trapping during summer and autumn in eight indigenous forest fragments (mean 5 ha) in rural landscapes of Waikato, a lowland pastoral farming district of the North Island, New Zealand. Four of the eight were fenced and four grazed. In each set of four, half were connected with hedgerows, gullies or some other vegetative corridor to nearby forest and half were completely isolated. Summer rat density based on the number trapped in the first six nights was higher in fenced (mean 6.5 rats ha–1) than in grazed fragments (mean 0.5 rats ha–1; P = 0.02). Rats were eradicated (no rats caught and no rat footprints recorded for three consecutive nights) from all eight fragments in January–April 2008, but reinvaded within a month; time to eradication averaged 47 nights in fenced and 19 nights in grazed fragments. A second six-night trapping operation in autumn, 1–3 months after eradication, found no effect of fencing (P = 0.73). Connectedness to an adjacent source of immigrants did not influence rat density within a fragment in either season (summer P = 0.25, autumn P = 0.67). An uncalibrated, rapid (one-night) index of ship rat density, using baited tracking tunnels set in a 50 × 50 m grid, showed a promising relationship with the number of rats killed per hectare over the first six nights, up to tracking index values of c. 30% (corresponding to c. 3–5 rats ha–1). The index will enable managers to determine if rat abundance is low enough to achieve conservation benefits. Our results confirm a dilemma for conservation in forest fragments. Fencing protects vegetation, litter and associated ecological processes, but also increases number of ship rats, which destroy seeds, invertebrates and nesting birds. Maximising the biodiversity values of forest fragments therefore requires both fencing and control of ship rats. |
format |
Article in Journal/Newspaper |
author |
Innes, John G. King, Carolyn M. Bridgman, Lucy Jade Fitzgerald, Neil Arnold, Greg Cox, Neil R. |
author_facet |
Innes, John G. King, Carolyn M. Bridgman, Lucy Jade Fitzgerald, Neil Arnold, Greg Cox, Neil R. |
author_sort |
Innes, John G. |
title |
Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand |
title_short |
Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand |
title_full |
Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand |
title_fullStr |
Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand |
title_full_unstemmed |
Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand |
title_sort |
effect of grazing on ship rat density in forest fragments of lowland waikato, new zealand |
publisher |
New Zealand Ecological Society |
publishDate |
2010 |
url |
https://hdl.handle.net/10289/3879 |
geographic |
New Zealand |
geographic_facet |
New Zealand |
genre |
Rattus rattus |
genre_facet |
Rattus rattus |
op_relation |
http://www.nzes.org.nz/nzje/new_issues/NZJEcol34_2_227.pdf New Zealand Journal of Ecology Innes, J., King, C.M., Bridgman, L., Fitzgerald, N., Arnold, G. & Cox, N. (2010). Effect of grazing on ship rat density in forest fragments of lowland Waikato, New Zealand. New Zealand Journal of Ecology, 34(2), 227-232. https://hdl.handle.net/10289/3879 |
op_rights |
This article has been published in the journal: New Zealand Journal of Ecology. © 2010 New Zealand Ecological Society. Used with permission. |
_version_ |
1772819158840377344 |