Reinvasion by ship rats (Rattus rattus) of forest fragments after eradication

Carolyn King, John Innes, Dianne Gleeson, Neil Fitzgerald, Tom Winstanley, Barry O'Brien, Lucy Bridgman, Neil Cox

    Research output: Contribution to journalArticle

    28 Citations (Scopus)

    Abstract

    Reinvasions provide prime examples of source-sink population dynamics, and are a major reason for failure of eradications of invasive rats from protected areas. Yet little is known about the origins and population structure of the replacement population compared with the original one. We eradicated eight populations of ship rats from separate podocarp- broadleaved forest fragments surrounded by open grassland (averaging 5.3 ha, scattered across 20,000 ha) in rural landscapes of Waikato, New Zealand, and monitored the- re-establishment of new populations. Rats were kill-trapped to extinction during January to April 2008, and then again after reinvasion in April–May (total n = 517). Rats carrying Rhodamine B dye (n = 94), available only in baits placed 1–2 months in advance in adjacent source areas located 170–380 m (average 228 m edge to edge) away, appeared in 7 of the 8 fragments from the first day of the first eradication. The distribution of age groups, genders and proportions of reproductively mature adults (more immature juvenile males and fewer fully mature old females) was different among marked rats compared with all other rats (P = 0.001, n = 509); in all rats caught on days 7? of the first eradication compared with on days 1–6 (P = 0.000); and in the total sample collected in fragments by trapping to and after local extinction compared with in brief, fixed-schedule sampling of populations in continuous forests (P = 0.000). Genotyping of 493 carcases found no significant population-level differentiation among the 8 fragments, confirming that the rats in all fragments belonged to a single dynamic metapopulation. Marked rats of both genders travelled up to 600 m in a few days. Conservation of forest fragments is compromised by the problem that ship rats cannot be prevented from rapidly reinvading any cleared area after eradication.
    Original languageEnglish
    Pages (from-to)2391-2408
    Number of pages18
    JournalBiological Invasions
    Volume13
    DOIs
    Publication statusPublished - 2011

    Fingerprint

    Rattus rattus
    ships
    habitat fragmentation
    rats
    gender
    rural landscape
    local extinction
    bait
    metapopulation
    population structure
    trapping
    protected area
    dye
    population dynamics
    replacement
    extinction
    grassland
    sampling
    ship
    baits

    Cite this

    King, C., Innes, J., Gleeson, D., Fitzgerald, N., Winstanley, T., O'Brien, B., ... Cox, N. (2011). Reinvasion by ship rats (Rattus rattus) of forest fragments after eradication. Biological Invasions, 13, 2391-2408. https://doi.org/10.1007/s10530-011-0051-6
    King, Carolyn ; Innes, John ; Gleeson, Dianne ; Fitzgerald, Neil ; Winstanley, Tom ; O'Brien, Barry ; Bridgman, Lucy ; Cox, Neil. / Reinvasion by ship rats (Rattus rattus) of forest fragments after eradication. In: Biological Invasions. 2011 ; Vol. 13. pp. 2391-2408.
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    author = "Carolyn King and John Innes and Dianne Gleeson and Neil Fitzgerald and Tom Winstanley and Barry O'Brien and Lucy Bridgman and Neil Cox",
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    King, C, Innes, J, Gleeson, D, Fitzgerald, N, Winstanley, T, O'Brien, B, Bridgman, L & Cox, N 2011, 'Reinvasion by ship rats (Rattus rattus) of forest fragments after eradication', Biological Invasions, vol. 13, pp. 2391-2408. https://doi.org/10.1007/s10530-011-0051-6

    Reinvasion by ship rats (Rattus rattus) of forest fragments after eradication. / King, Carolyn; Innes, John; Gleeson, Dianne; Fitzgerald, Neil; Winstanley, Tom; O'Brien, Barry; Bridgman, Lucy; Cox, Neil.

    In: Biological Invasions, Vol. 13, 2011, p. 2391-2408.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Reinvasion by ship rats (Rattus rattus) of forest fragments after eradication

    AU - King, Carolyn

    AU - Innes, John

    AU - Gleeson, Dianne

    AU - Fitzgerald, Neil

    AU - Winstanley, Tom

    AU - O'Brien, Barry

    AU - Bridgman, Lucy

    AU - Cox, Neil

    PY - 2011

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    N2 - Reinvasions provide prime examples of source-sink population dynamics, and are a major reason for failure of eradications of invasive rats from protected areas. Yet little is known about the origins and population structure of the replacement population compared with the original one. We eradicated eight populations of ship rats from separate podocarp- broadleaved forest fragments surrounded by open grassland (averaging 5.3 ha, scattered across 20,000 ha) in rural landscapes of Waikato, New Zealand, and monitored the- re-establishment of new populations. Rats were kill-trapped to extinction during January to April 2008, and then again after reinvasion in April–May (total n = 517). Rats carrying Rhodamine B dye (n = 94), available only in baits placed 1–2 months in advance in adjacent source areas located 170–380 m (average 228 m edge to edge) away, appeared in 7 of the 8 fragments from the first day of the first eradication. The distribution of age groups, genders and proportions of reproductively mature adults (more immature juvenile males and fewer fully mature old females) was different among marked rats compared with all other rats (P = 0.001, n = 509); in all rats caught on days 7? of the first eradication compared with on days 1–6 (P = 0.000); and in the total sample collected in fragments by trapping to and after local extinction compared with in brief, fixed-schedule sampling of populations in continuous forests (P = 0.000). Genotyping of 493 carcases found no significant population-level differentiation among the 8 fragments, confirming that the rats in all fragments belonged to a single dynamic metapopulation. Marked rats of both genders travelled up to 600 m in a few days. Conservation of forest fragments is compromised by the problem that ship rats cannot be prevented from rapidly reinvading any cleared area after eradication.

    AB - Reinvasions provide prime examples of source-sink population dynamics, and are a major reason for failure of eradications of invasive rats from protected areas. Yet little is known about the origins and population structure of the replacement population compared with the original one. We eradicated eight populations of ship rats from separate podocarp- broadleaved forest fragments surrounded by open grassland (averaging 5.3 ha, scattered across 20,000 ha) in rural landscapes of Waikato, New Zealand, and monitored the- re-establishment of new populations. Rats were kill-trapped to extinction during January to April 2008, and then again after reinvasion in April–May (total n = 517). Rats carrying Rhodamine B dye (n = 94), available only in baits placed 1–2 months in advance in adjacent source areas located 170–380 m (average 228 m edge to edge) away, appeared in 7 of the 8 fragments from the first day of the first eradication. The distribution of age groups, genders and proportions of reproductively mature adults (more immature juvenile males and fewer fully mature old females) was different among marked rats compared with all other rats (P = 0.001, n = 509); in all rats caught on days 7? of the first eradication compared with on days 1–6 (P = 0.000); and in the total sample collected in fragments by trapping to and after local extinction compared with in brief, fixed-schedule sampling of populations in continuous forests (P = 0.000). Genotyping of 493 carcases found no significant population-level differentiation among the 8 fragments, confirming that the rats in all fragments belonged to a single dynamic metapopulation. Marked rats of both genders travelled up to 600 m in a few days. Conservation of forest fragments is compromised by the problem that ship rats cannot be prevented from rapidly reinvading any cleared area after eradication.

    KW - Invasive predators

    KW - Reinvasion

    KW - Roof rat

    KW - Black rat

    KW - Forest fragment

    KW - Genetic differentiation

    KW - Eradication units.

    U2 - 10.1007/s10530-011-0051-6

    DO - 10.1007/s10530-011-0051-6

    M3 - Article

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