In 1989, the kakerori (Pomarea dimidiata) was one of the 10 rarest birds in the world with a declining population of just 29 individuals living in forested hill country in the Takitumu Conservation Area (TCA) of south-eastern Rarotonga, Cook Islands. Following 12 years of rat poisoning, the population had increased to 255 birds in August 2001. The programme then shifted from species recovery to sustainable management of the Rarotonga population at 250 to 300 birds. The rat poisoning effort was reduced, and an insurance population was established on Atiu. By August 2004, following the reduction of poisoning from weekly to fortnightly, and the transfer of 30 youngsters to Atiu in 200103, there were 281 birds on Rarotonga and 25 on Atiu. The southern Cook Islands were hit by five tropical cyclones in a four-week period in FebruaryMarch 2005, and forests on Rarotonga were severely damaged. Kakerori survived the storms remarkably well, but the main effect was observed in the following breeding season (2005/06), when nesting success on Rarotonga was exceptionally poor. Reduced canopy cover caused nests to be exposed to abnormally wet conditions, and lack of fruit meant that rats were exceptionally hungry. Only 31 yearlings were known to be alive in August 2006about half the expected numberand annual mortality of banded birds (25%) was the highest since management began. The kakerori population on Rarotonga fell 8% from 275 birds in August 2005 to a minimum of 254 birds in August 2006. The situation was better on Atiu, with the population growing from about 32 adult birds in 2005/06 to a minimum of 37 adult birds in 2006/07, and an Atiu-bred pair nested successfully for the first time. The 2006/07 breeding season on Rarotonga was moderately successful, with a minimum of 51 fledglings found. Because the sustainable management regime of fortnightly rat poisoning in the TCA was only just adequate in giving protection to adult kakerori, the annual poisoning programme was modified by adding rounds of interim poisoning in April and July 2007 aimed at reducing rat and cat numbers before the breeding season.
In June/July 2002 the eradication of Pacific rats from Maninita Island in the Vava'u group of the Kingdom of Tonga was attempted using Brodifacoum pellets in bait stations. In December 2002, Maninita was revisited and rat trapping carried out to determine if rats were present. While no rats were caught and none were seen, further monitoring in June 2003 is recommended before the island is declared "rat free '.
Using the same techniques used on Maninita, the eradication of rats on neighbouring Taula and Lua Loli was attempted. Despite poor weather delaying rebaiting visits to the islands, the
operation thus far appears successful.
Permanent bait stations set up on Maninita to minimise the risk of rats re-invading the island were found to have been tampered with and evidence of booby chick harvesting was seen on
Taula. Regular visits to the islands to maintain bait stations and maintain a presence are recommended.
In June/July 2002 an eradication programme to remove Pacific rats from Maninita Island in the Vava'u group of the Kingdom of Tonga was initiated. The techniques used were similar to those
used in successful rat eradications in New Zealand, in that Pestoff 20R pellets and a network of bait stations were used.
Conditions on the island were not what was expected, the forest having been adversely affected by cyclone Waka and subsequent defoliation by caterpillars, resulting in an open forest canopy. Rats were found to be present on the island in high numbers and were breeding.
At this stage it appears that the operation was successful, as no rats were caught in monitoring trapping after 20 days of operations, although follow-up monitoring needs to be carried out in late 2002 to confirm this. There appears to have been no negative impact on non-target species.
At the time of the POBSP visit, cats (Felis domestica), dogs
(Canis familiaris), and pigs (Sus scrofa) were being raised by the natives. Comments in Ward (1967) and by Lamont (1867) suggest that the pigs may have been introduced to Tongareva in 1853 from the ship wrecked vessel Chatham. Rats (Rattus sp.) were numerous in 1965, but as no specimens were collected their identity is unknown. Lamont (1867) stated that in 1853 "... [the natives] had never seen an animal larger than a very small rat, that lives principally in the cocoa-nut trees " Lamont's description suggests that the rats on Tongareva are Rattus elegans, a species widely distributed on the Pacific Islands.
The Tokelau Islands consist of three atolls (Atafu, Nukunonu and Fakaofo) approximately 500 km north of Western Samoa. Their numerous islets are formed mainly of coral sand and rubble with no standing freshwater. Sixty-one plant species have been recorded, 13 of these being introduced and 10 being adventives. There are three vegetation zones, the beach, the beach-crest, and the interior coconut/fern zone with the physiognomy of a humid tropical forest. Marine invertebrates have not been studied. One hundred and fifty insect species in 83 families have been recorded with most being widely distributed South
Pacific species including several introduced agricultural pests, e.g. Rhinoceros Beetle. Some marine fishes have been listed and 7 species of lizards are known from the group. Twenty-six bird species (15 sea birds, 8 shore birds and 3 land birds) are known but none are endemic races. Domestic pigs, cats, man and the Polynesian Rat (Rattus exulans) are the only mammals. R. exulans is an economic pest as it causes considerable damage to the coconut crop and assists in the spread of filariasis.
The study of dispersal processes of small mammals, and especially of rodents, has a wide range of applications and until recent years there were few publications discussing the
colonisation of 'oceanic' islands by small mammals (cf. Crowell, 1986; Diamond, 1987; Hanski, 1986;Heany, 1986; Lomolino, 1986).
This essay will be concerned with the distribution of rat species in the Marshall Islands and its implications on the interpretation of the settlement and human use of the atolls. It will be argued that in all instances the introduction of rats was caused by people and that accidental transport, such as rafting on drift wood and the like, is as unlikely as introduction by means of ship wrecks. Human transport as well as the rats' own inability to cross great distances of water makes them bad zoogeographical markers, as already pointed out by
Braestrup (1956), but it is precisely this trait that is of concern here. This paper will argue that the Polynesian rat (Rattus exulans) was an intentional introduction to the area and that its distribution throughout the Marshall Islands was a deliberate strategy.
Through the Pohnpei Rat Eradication Research and Demonstration Project, The Conservation: Society of Pohnpei (CSP), Island Conservation (IC), and the Pacific Invasives Initiative (PII) are working together to enhance the biosecurity of Pohnpei's island ecosystems, and that of other similar ecosystems throughout the Pacific. This research and demonstration project will help NGO and government conservation organizations develop the capacity to plan. fund, and implement subsequent: rat eradications in threatened island ecosystems. CSP, IC, and PII also partnered with the following organizations to cany out this pioneering conservation project: the Pacific Invasives Learning
Network, The Nature Conservancy, the Pohnpei State Government, the Micronesia Conservation Trust, Micronesians in Island Conservation, local government officials, and local landowners.
Rattus rattus, or black rats, are rampaging through Tuvalu's atolls and gnawing through the country's chief export crop - coconuts.
Coconuts and copra (dried coconut flesh from which coconut oil is made) are the islander's main source of revenue.
On 6 January 2004. cyclone Heta devastated much of the South Pacific island nation of Niue. Extensive damage was done to forest, particularly of the north- western sector, with many trees up-rooted and others stripped of branches and foliage. This report details our findings from a survey of Niue's birds and rodents during 3-19 September 2004 and compares these with results from a similar survey in September 1994. Five-minute bird count data, an index of conspicuousness, from three transects showed that heahea (Polynesian triller,Lalagc maculosa) were more abundant in 2004 than in 1994, but mid
(Polynesian starling, Aplonis tabuensis), kulukulu (purple-crowned fruit dove. Ptilinopus porpbyraecus) and lupe (Pacific pigeon. Ducula pacifica) had declined. The 28-64% decline in the lupe population per transect w as probably primarily as a result of hunting, rather than mortality caused by cyclone Heta.
Counts of birds seen per kilometre along three sections of road (lower, upper, inland) were also compared with September 1994 data. However, for various reasons we doubt that the results accurately reflect population numbers. The 212 kiu (Pacific golden plover. Pluvial is fulva) counted at sites accessible from main roads in September 2004 was similar to the 226 seen in September 1994. Rat trapping results (captures per 100 trap-nights) along the same three transects for December 1994 and September 2004 were not significantly different. Both kuma (Pacific rat. Rattus exulans) and ship rats (R. rattus) were
trapped, but kuma were found only in regenerating scrub, whereas ship rats were present in both scrub and forest. Recommendations for future work are made mainly in relation to the long-term conservation of lupe, a toaga (treasured) species of Niueans.
