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   Rattus norvegicus (mammal)
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    Details of this species in Fregate Is.
    Status: Alien
    Invasiveness: Invasive
    Occurrence: Eradicated
    Source: Island Conservation and Ecology Group, 2004
    Arrival Date: 1995
    Introduction:
    Species Notes for this Location:
    Fregate Island was the last remaining rat-free island larger than 100 ha of the Seychelles prior to 1995, when rats were accidentally introduced. A population quickly became established on the island (Millet and Shah, 2001).
    Management Notes for this Location:
    Initial attempts to eradicate the rats while the population was still small were abandoned when some Seychelles magpie-robins (see Copsychus sechellarum in IUCN Red List of Threatened Species) were poisoned by the rodenticide used. In June of 2000, a second attempt was made. Three aerial applications of brodifacoum (20ppm) were carried out, at a rate of 35 kg/ha, with five and 24 days between the applications. This programme was undertaken by the Seychelles Ministry of Environment (led by Don Merton), and cost US$54,000. Prior to the application of bait, 39 magpie-robins, 330 Seychelles fodys (see Foudia sechellarum in IUCN Red List of Threatened Species), and Aldabran giant tortoises (see Geochelone gigantea in IUCN Red List of Threatened Species) were taken into captivity. Rats were declared eradicated in June 2002. Since then, no mortality has been recorded in recently fledged Seychelles magpie-robins. It is now important to implement strict quarantine procedures, and enhance community awareness, to maintain the rat-free status of Fregate Island. There is a rodent-proof fence in place around the harbour, but this must be maintained in order to remain rodent-proof (Millet, 2001; Thornsen et al. 2000; www.pestoff.co.nz; Merton et al. 2002; Merton, pers. Comm.). (See Hill et al. (2003) and Thorsen et al. (2000) for more details).
    Location Notes:
    The vegetation of Fregate Island (219 ha) is primarily forested. It is a privately owned island which was managed as a copra plantation until the 1950s. The forest is now dominated by coconut Cocos nucifera, cashew (Anacardium occidentale), and other formerly cultivated species. Fregate Island is a refuge for two bird species, three invertebrates and a mollusc which are endemic to the Seychelles. It supports the largest populations of six endemic reptiles (Merton et al. 2002).
    Impacts:
    Human nuisance: Rattus norvegicus were a nuisance to the plantation and hotel on Fregate Island (Millet and Shah, 2001).
    Reduction in native biodiversity: Rattus norvegicus impacted on the avifauna and invertebrates of Fregate Island (Millet and Shah, 2001).
    Last Modified: 21/08/2006 4:07:23 p.m.


ISSG Landcare Research NBII IUCN University of Auckland