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Breeding success of 5 Cory’s shearwater Calonectris diomedea sub-colonies of Lavezzu Island (Lavezzi Archipelago, Corsica) was checked annually for 25 consecutive years from 1979 to 2004. Between 1989 and 1994, 4 ship rat Rattus rattus controls were performed in several subcolonies. In November 2000, rats were eradicated from Lavezzu Island and its 16 peripheral islets (85 ha) using traps then toxic baits. We compare cost (number of person-hours required in the field) and benefit (Cory’s shearwater breeding success) of control and eradication. The average breeding success doubled when rats were controlled or eradicated (0.82) compared to the situation without rat management (0.45). Moreover, the average breeding success after eradication (0.86) was significantly (11%) higher than after rat controls (0.75). Furthermore, the great variation in breeding success recorded among sub-colonies both with and without rat control declined dramatically after eradication, suggesting that rats had a major impact on breeding success. The estimated effort needed to perform eradication and checking of the permanent bait-station system during the year following eradication was 1360 person-hours. In contrast, rat control was estimated to require 240 or 1440 person-hours per year when implemented by trained and untrained staff, respectively. Within 6 yr, eradication cost is lower than control cost performed by untrained staff and confers several ecological advantages on more ecosystem components than Cory’s shearwater alone. Improved eradication tools such as hand or aerial broadcasting of toxic baits instead of the fairly labour-intensive eradication strategy we used would dramatically increase the economic advantage of eradication vs. control. Therefore, when feasible, we recommend eradication rather than control of non-native rat populations. Nevertheless, control remains a useful management tool when eradication is not practicable.

Niue is a single raised coral atoll in the South-central Pacific located at latitude 19 S and Longitude 169 W. It is isolated, being approximately 480 kilometre East of Tonga. 930 kilometre west of Rarotonga and 660 kilometre South-East of Samoa. The island is the largest raised coral atoll in the world, being 259 square kilometers and formed of two terraces: a lower terrace averaging about 60 metres. The interior is a plateau, the edge of which slopes steeply down to the lower terrace. This lower terrace ends abruptly in most places in steep cliffs containing caves and deep chasms

The endemic kereru (Hemiphaga novaeseelandiae) (also known as kuku, kukupa or New Zealand pigeon, but henceforth referred to as kereru) and the Chatham Island subspecies, parea (Hemiphaga novaeseelandiae chathamensis), are the only extant representatives of the genus Hemiphaga. A programme has been set up to monitor kereru populations. The aim of this monitoring programme is to provide a clearer picture of medium- to long-term trends in kereru populations at key sites (e.g., mainland “island” management sites and their paired non-treatment sites), and to document the responses of kereru populations to management actions. This report sets out the requirements for monitoring kereru at key sites as part of a national programme. In addition, it is intended to be used as a practical guide for anyone (e.g., iwi, conservation groups, school groups) planning to initiate a kereru monitoring project. The most efficient way of detecting and interpreting kereru population trends is considered to be by undertaking 5-minute counts with distance estimates in conjunction with phenology monitoring and display flight monitoring. It is therefore recommended that others use these methods wherever possible. A section on other techniques is included to cover situations where 5-minute counts may not be practicable. Wherever possible, kereru monitoring should be integrated into existing Department of Conservation bird monitoring and management programmes, rather than requiring the initiation of new projects. Iwi, conservation groups and interested members of the public will be encouraged to participate in kereru monitoring and conservation management. Annual results from each site should be forwarded to the programme co-ordinator, who will review and collate the data, and prepare an annual report for distribution to all participants and interested parties. Explanation of the programme, relevant aspects of kereru ecology, and background information are provided in the main text. Descriptions of the actual methods are given in the appendices.