This report presents the findings of a research project conducted on the island of Nuutele. An offshore uninhabited island lying east of the main island of Upolu, Samoa. The island is home and haven to sea birds and most endangered endemic and native land birds of Samoa. However, the invasion of the island by rat of unknown species, population and distribution has raised the concern for serious wildlife management actions to protect the islands' bio-diversity. In an attempt to investigate the feasibility of performing such an ecological management approach, a serious of field investigations were carried out from July 2000 to June 2001 on the island. These studies was funded by AusAid under the Nuutele Island Rodent Eradication Project through the Invasive Species Management Program currently coordinated and administered by SPREP. The
fieldwork activities involved were coordinated and led by the author with strong technical support and advice from staff of the Department of Conservation in New Zealand. Massey University, International Wildlife Consultants. Local Consultants and staff, and the Invasive Species Management Project Manager of SPREP.
In 1989, the kakerori (Pomarea dimidiata) was one of the 10 rarest bird
species in the world with a declining population of just 29 birds. During each
breeding season since then, rats have been poisoned within the 155 ha of
forested hill country they occupy in southeastern Rarotonga. As a result, the
kakerori population has rebounded, with a minimum of 259 birds being found
on Rarotonga in August 2002. In 2001 and 2002, 20 yearlings were transferred
to Atiu in the first two of three planned annual transfers to establish an
insurance population. In January 2003, three pairs of kakerori were found on
Atiu, and successful breeding was proven with the discovery of six island-bred
(unbanded) birds, belonging to at least two of the pairs. In 2002/03, the
emphasis of management in the Takitumu Conservation Area shifted from the
recovery of kakerori to a programme aimed at sustaining the population at
about 250 individuals. The key to this work was the experimental reduction of
rat poisoning effort, so that 30 territories had the standard weekly refills of
poison bait stations, 29 received a fortnightly refill, and 20 received no rat
control. As expected, breeding success was significantly better in poisoned
areas (with an average of 0.95 fledglings per breeding territory) than in
unpoisoned areas (with an average of 0.30 fledglings per breeding territory).
This reduced rat control programme took 23 person days each week for 15
weeks, and used a total of 43 kg of Talon® (active ingredient brodifacoum),
which was about 20% of peak poison use during the recovery phase of the
programme. The fortnightly poisoning regime offers promise as an effective,
cheaper and less toxin-intensive method than that used previously.
