Successful eradication of invasive rodents from a small island through pulsed baiting inside covered stations

Abstract

We show the results of an eradication campaign against Rattus rattus developed in Rey Francisco Island (12 ha), Chafarinas islands, southwestern Mediterranean. Rat population size was estimated by snap trapping in up to 93.47 ind./ha and a trapping index of 9.58 captures/100 traps-night. We think that population was underestimated because of the number of traps found strung but without capture. Several products were tested in order to define the method of eradication. In 1992, we selected a second generation anticoagulant, pelleted brodifacoum 50 ppm into 5 l plastic containers as baiting stations. Bait consumption reached zero after three pulses, and intensive searching of tracks and signals were unsuccessful. After more than two years of absence of signals and sightings, in 1995, rat scats were observed in Rey Francisco, and the population rose dizzily. After several snap-trapping sessions in 1996, 1997 and 1999, when trapping success reached 37 captures/100 trap-nights, a new campaign started in autumnÀwinter 1999À2000 using flocoumafen 50 ppm inside 180 baiting stations. Eradication occurred with a very low risk for non-target fauna, setting less than 1 kg/ha of bait each time. Monitoring, both with snap traps and baiting at a lower intensity assures the absence of reinvasion.

Rat control and breeding performance in Cory's shearwater (Calonectris diomedea): effects of poisoning effort and habitat features

“…These tests suggested the use of 16 g briquettes made with a mixture of cereals, wax and the anticoagulant 'Flocoumafen' (a second generation poison) (see details in Orueta et al, 2005). Once the raw materials to be used were decided, the same methodology was applied during the whole study.…”

“…The use of snap-trap lines made it possible to estimate an abundance index and to compare results among years. Snap trapping is commonly used as a tool for estimating rodent density (Hooker & Innes, 1995;Shanker, 2000;Micol & Jouventin, 2002;Orueta et al, 2005). We placed 30 snaptrap stations baited with wick soaked in fish oil, separated by 15 m intervals.…”

Grain, pellet and wax block bait take by the house mouse (Mus musculus) and non‐target species: implications for mouse eradications on coral cay islands

“…The nutritional information listed on the product label was: minimum 18.5% crude protein, maximum 4% crude fibre, added selenium 0.10 mg kg -1 and added copper 5 mg kg -1 . Pellet baits containing anticoagulant rodenticide are currently used for the eradication of rodent pests on islands in New Zealand (Empson & Miskelly 1999;Orueta et al 2005).…”

“…Since the 1970s introduced rodents have been eradicated from more than 100 islands worldwide (for examples see: Taylor & Thomas 1989;Taylor et al 2000;Saunders & Brown 2001;Towns & Broome 2003;Orueta et al 2005). In Western Australia alone, introduced rats have been eradicated from more than 31 islands since 1981 (Burbidge & Morris 2002).…”

Testing island biosecurity systems for invasive rats

“…species (Courchamp et al 2003). The detection and elimina- Orueta et al 2005). The fallacy of this assumption has now tion of invasive species is therefore fundamental to conservabeen demonstrated on islands invaded by rats despite the prestion of island systems.…”