The UK has sovereignty over 16 Overseas Territories, which hold some of the world's great seabird colonies and collectively support more endemic and globally threatened bird species than the whole of mainland Europe. Invasive alien mammalian predators have spread throughout most of the Territories, primarily since European expansion in the 16th century. Here we review and synthesize the scale of their impacts, historical and current, actions to reduce and reverse these impacts, and priorities for conservation. Mammalian predators have caused a catastrophic wave of extinctions and reductions in seabird colony size that mark the UKOTs as a major centre of global extinction. Mammal-induced declines of threatened endemics and seabird colonies continue, with four Critically Endangered endemics on Gough Island (Tristan da Cunha), St Helena and Montserrat directly threatened by invasive alien House Mice Mus musculus, Feral Cats Felis catus and rats Rattus spp. Action to reduce these threats and restore islands has been modest in comparison with other developed countries, although some notable successes have occurred and a large number of ambitious eradication and conservation plans are in preparation. Priority islands for cosnervation action against mammalian predators include Gough (which according to one published prioritization scheme is the highest-ranked island in the world for mammal eradication), St Helena and Montserrat, but also on Tristan da Cunha, Pitcairn and the Falkland Island. Technical, financial and political will is required to push forward and fund the eradication of invasive mammalian predators on these islands, which would significantly reduce extinction risk for a number of globally threatened species.
In November 2007 and November 2008, we conducted a bird and mammal survey on Wallis and Futuna. We found two non-native bird species on Wallis: the Common Myna (Acridotheres tristis) and the Chestnut-breasted Munia (Lonchura castaneothorax), and one on Futuna: the Jungle Myna (Acridotheres fuscus). We also recorded Black Rats (Rattus rattus) on Futuna, a recent introduction to this island. The introduction of 3 bird species and Black Rats in the last decade denotes a lack of preventive measures and demonstrates that the issue of invasive species has not received sufficient priority.
In November 2007 and November 2008, we conducted a bird and mammal survey on Wallis and Futuna. We found two non-native bird species on Wallis: the Common Myna (Acridotheres tristis) and the Chestnut-breasted Munia (Lonchura castaneothorax), and one on Futuna: the Jungle Myna (Acridotheres fuscus). We also recorded Black Rats (Rattus rattus) on Futuna, a recent introduction to this island. The introduction of 3 bird species and Black Rats in the last decade denotes a lack of preventive measures and demonstrates that the issue of invasive species has not received sufficient priority
The second pigs eradication was a follow up activity of the first eradication as it was reported that there are still more pigs on the island that needs to be cleared off. It is a concern to remove pigs from the island because of the high risk that lies ahead on human health from the toxic bait that will kill the rats during the rat eradication operation when pigs consume this toxic bait. Assessment and advices was given that this toxic bait will affect the pigs when consuming it also people will intake the impact when they eat these affected pigs as some pigs wont die from up taking a small amount of bait but has a potential to live and in that case they will be carrier of this toxic bait. Pigs are also on the other hand destructors of the natural biodiversity on the island particularly the plants and the landscape of the island. It is also suspected to be the worst predator of turtle eggs which also contribute to the loss of this species as this island is one of the nesting ground for turtles. This second activity was carried out on the 11th to 15th April with the assistance from the Water sector staff and a local hunter that was hired which makes this task successful.
The restoration of the Islands of Nuutele and Nuulua is a priority of the Government of Samoa and the communities of Aleipata District. Planning is well advanced on a key element of this, the eradication of Pacific Rats (Rattus exulans) by aerial
spreading of toxic baits in mid-2006. The Friendly Ground Dove has been identified as a non-target species that may be at risk of taking the baits and one for which the Nuutele and Nuulua populations are significant. Several approaches for safeguarding
these have been discussed and this expedition was designed to test the feasibility of the preferred approach, namely the capture and holding of birds in a safe situation on Nuutele during the aerial operation and their release once the baits are non-toxic.
The islands of Nu'utele and Nu'ulua have been identified as highly significant sites for conservation in Samoa. They hold large populations of species currently found nowhere else in the country' including threatened land-birds, seabirds and nesting
turtles. They also are the only offshore islands large enough and far enough offshore to be considered as refuges for several of the nation's species threatened on the larger islands by introduced mammalian pests. Such refuges have assumed greater
importance as recent severe cyclones (Ofa - 1990, Val - 1991 & Heta - 2004) have reduced bird and bat numbers.
For one of the species potentially at some risk of poisoning under the proposed rat eradication regime, the Friendly Ground Dove, Nuutele and Nuulua hold populations that are nationally significant. The complete loss of these populations would threaten the survival of the taxon in Samoa. Some authors consider the Samoan doves to be a separate race (Gallicolumba s. stairi) from those in Fiji and Tonga (Watling, 2001). Outside Samoa, the race is only found on the small island of Ofu,
American Samoa where it is threatened. So the loss of Nuutele and Nu'ulua birds could threaten the race with extinction.
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 the Takitumu Conservation Area in southeastern Rarotonga. As a result, the kakerori population has rebounded, with a minimum of 292 birds found on Rarotonga in August 2003. In 2001/02, the emphasis of management shifted from the .recovery. of kakerori to a programme aimed at .sustaining. the population at 250.300 individuals. The major changes were an experimental reduction in rat poisoning effort to a level where recruitment of kakerori balances annual mortality, and a series of transfers to establish an insurance population on the island of Atiu. In 2003/04, all bait stations were filled fortnightly, rather than the previous mix of weekly and fortnightly refills. This reduced labour costs by 30% to 32 person days, and used a total of 39 kg of Talon® (active ingredient brodifacoum), which was only 13% of the maximum annual poison use over the same area during the .recovery. phase of the programme. Breeding success was high (0.91 fledglings/ breeding territory), even in the unpoisoned areas, and a record total of 80 fledglings was detected. The fortnightly poisoning regime offers promise as an effective, cheaper and less toxin-intensive method than that used previously, and so we recommend maintaining this regime in 2004/05, so that the longerterm effects can be assessed. A third and final batch of 10 young kakerori was transferred to Atiu Island in August 2003. This .insurance. population is becoming well established; the five breeding pairs monitored in 2003/04 each raised two fledglings, and a minimum of 15 birds was found in May.June 2004 in the small part of the island that was searched.
In 1989, the kakerori (Pomarea dimidiata) was one of the ten rarest bird species in the world, with a declining population of just 29 birds living in south-eastern Rarotonga. As a result of conservation management, the kakerori population has rebounded, with a minimum of 281 birds on Rarotonga and 19 birds on Atiu in summer 2004/05. Since 2001, the emphasis of management in the Takitumu Conservation Area (TCA) on Rarotonga has shifted from the recovery of kakerori to sustaining the population at 250300 individuals. In 2004/05, all rat bait stations were filled fortnightly, and so the labour costs were reduced by 30% to 34 person days, and toxin use (57 kg of Talon®active ingredient brodifacoum) was reduced 81% from the peak year during the recovery phase. Kakerori breeding productivity was unusually high in 2004/05 because several pairs raised two broods. In the poisoned area, apparent breeding success was significantly higher (1.35 fledglings/breeding territory) than in the unpoisoned area (0.55 fledglings/ breeding territory); however, this difference was at least partly due to more effort being spent searching for fledglings in poisoned areas. A minimum of 59 fledglings was detected in 2004/05; however, some territories were not checked during the breeding season, and then a series of five tropical cyclones struck Rarotonga in a 4-week period in February/March 2005, which halted our fledgling searches, and caused severe damage to some habitat in the TCA. We expect that many kakerori perished during these cyclones; however, the population on Atiu, which was only affected by two of the five cyclones, survived unscathed. These catastrophic weather events highlighted the vulnerability of single-island endemic birds, and underlined the value of establishing an insurance population on Atiu. We recommend that the poisoning regime should return to that used during the recovery phase of the kakerori management programme if the August 2005 census reveals that the population has fallen below 220 birds (a 20% decline), otherwise the recent programme of fortnightly poisoning should continue.
In 1989, the kakerori (Pomarea dimidiata) was one of the ten rarest bird species in the world, with a declining population of just 29 birds in the Takitumu Conservation Area (TCA) of southeastern Rarotonga. As a result of conservation management, the kakerori population rebounded, with up to 300 birds being recorded on Rarotonga and Atiu in 2004/05. The southern Cook Islands was, however, hit by five tropical cyclones over a 4-week period in FebruaryMarch 2005, and much of the forest on exposed faces, spurs and ridges (traditional kakerori habitat) was severely damaged. The population survived remarkably well, with a minimum of 274 adults known to be alive in the TCA in August 2005. An additional 17 adults were found on Atiu between August 2005 and March 2006. The main\ casualties of the cyclones on Rarotonga appeared to be young birds (13 years old) and very old birds (> 20 years old). Because the population on Rarotonga remained well within the management target of 250300 individuals, rat poisoning was again done fortnightly, as in the previous 2 years. Breeding productivity was exceptionally poor in 2005/06, mainly because of nesting failures or early fledgling deaths caused by abnormally wet conditions during the main fledging periods. Nests were more exposed to the elements because the cyclones had extensively defoliated the canopy. Furthermore, rats were often seen foraging during the day, apparently struggling to find food (few trees were fruiting). Only 22 fledglings were definitely seen in 2005/06; however, some territories were not checked or poorly checked during the breeding season, and some fledglings may have dispersed to better vegetated sites. We recommend that rat control should return to the weekly poisoning regime used during the 19892001 recovery phase of the kakerori management programme if the August 2006 census reveals that the population has fallen below 220 birds (a 20% decline from pre-cyclone levels). Otherwise the regime of the sustainable management phase (fortnightly poisoning) should continue.
