Jewels Lost In
The Plight of the Vini Lorikeets of the South Pacific Islands
University of Adelaide, Australia
Among the lush tropical forests and palm trees of islands surrounded by the tropical, turquoise blue waters of the South Pacific live a group of lorikeets fittingly as spectacular as their surroundings. Described by numerous adventurers and naturalists to this part of the world as amongst the most beautiful of all birds the Vini genus of lorikeets consists of five charismatic, colourful species. Dotted on small islands across the South Pacific from Fiji in the west to Henderson Island 5000 kilometres away in the south-east they can appropriately be described as jewels lost in an ocean.
Conservation status and distribution
The South Pacific islands are recognised as having one of the highest rates of bird endemism in the world. This uniqueness is attributable to the isolation over long periods of time of the many small islands and archipelagoes in the region. Paradoxically, however, this isolation also makes the birds of these islands among the most threatened. Indeed, in historic times, the Pacific islands lay claim to the unenviable record of having the highest rate of bird extinction as a proportion of total species of any region on the planet. The susceptibility of the Pacific islands avifauna is a function of their naturally, relatively small population sizes, their confinement to islands that may be subject to rapid environmental changes and the relative inability of the islands’ birds to cope with introduced predators or competitors of continental origin. The situation facing the region’s avifauna is characterised by the plight of the Vini lorikeets. All five extant species have suffered notable declines in ranges and population sizes over the last few decades and two species have become extinct since human occupation of the region began .
The Tahitian lorikeet (V .peruviana) is one of the most distinctive and unusual of parrots being a deep, glossy blue all over except for a white bib and bright orange bill and legs. Although relatively widespread occurring from the Society Islands, the Tuamotu Archipelago and the Cook Islands (to where it was probably introduced) it is nonetheless considered Vulnerable having disappeared from 15 of the 23 islands it was once known to occur from. This species has been subject to a captive breeding effort by the San Diego Zoo which has unfortunately been unsuccessful in establishing a healthy breeding population.
The only surviving population within its natural range of Kuhl’s lorikeet (V. kuhlii), listed by the IUCN as Endangered, occurs on Rimatara in the central Pacific islands. Other introduced populations exist in the Austral Islands and on islands of Kiribati. This species only occurs from a few islands in each of these areas and is highly susceptible to rat predation of nests.
Stephen’s lorikeet (V.stepheni) a small, green, red and purple lorikeet, inhabits Henderson Island, an uninhabited raised-reef island in the Pitcairn Group in the south-central Pacific. Its population size is estimated at around 1200 pairs and given its confinement to this one island of 37 km² is listed by the IUCN as Vulnerable.
Although also decreasing in abundance, of all the Vini lorikeets the status of the Blue-crowned lorikeet (V.australis) is probably most secure. This species is endemic to some southern islands in the Fiji group, Tonga, Samoa and parts of central Polynesia.
Arguably, amongst the most spectacular of all our lorikeets is the Ultramarine lorikeet (Vini ultramarina) of French Polynesia (Fig.1). This gaudy little character, coloured in varying hues of blue and white, is justifiably recognised as the prettiest of the group and appropriately finds its home amongst the idyllic, tropical island setting of the Marquesas islands. Unfortunately, however, this species is also the most endangered occurring in very small numbers on three islands and one larger population on an island to which it was introduced. Subject to funding it will be the subject of proposed conservation efforts described below.
Threats and conservation requirements
The major threats facing the Vini include, loss and alteration of habitat due to deforestation and overgrazing, and human hunting for food, feathers and the pet trade. However, by far the most significant threat is from introduced predators, particularly rats. As major nest predators, rats are deemed responsible for having caused local extinctions of numerous bird species on many islands. Three rats, all introduced, occur in the region, the Black rat Rattus rattus, the Brown rat R. norvegicus and the Kiore R. exulans. Of these, black rats are believed to be the major threat to tree nesting birds because of their predominantly arboreal nature and appetite for eggs and young.
The principal need in terms of conservation of the Vini lorikeets is to introduce mitigation measures to minimise the threat posed by rats. In the short term, important nesting areas should be targeted for rat control, which should include baiting, use of tree guards to prevent access to nests and use of supplementary rat-proof nest boxes. Islands currently believed to be rat-free should be prioritised for measures to prevent rat introductions and consideration should be given to rat eradication from islands where practicable.
Conservation of the Ultramarine Lorikeet in the Marquesas Islands, French Polynesia.
In collaboration with the Ornithological Society of French Polynesia and subject to funding currently sought, an applied conservation-based research project is planned to address the plight of the endangered Ultramarine lorikeet in the Marquesas Islands. Of all the Vini lorikeets this species is at highest risk of extinction being classified as Endangered and on CITES ppendix 1.
Following surveys by The San Diego Zoological Society in the 1990’s the Ultramarine lorikeet was considered extinct from the two islands it originally occurred on, Nuku Hiva and Ua Pou. However, isolated birds have recently been re-discovered on both islands. These few individuals are the only Ultramarine lorikeets still found in their original historic range. Between 1992 and 1994 a translocation of 21 birds to Fatu Hiva (then found to be rat-free) was conducted and although by 1997 numbers were found to have increased, black rats have recently been discovered there, hence this population is now at high risk of extinction . The only relatively healthy population (900-1000 birds) exists on Ua Huka, an island currently believed to be rat-free. This population originated from a single pair introduced to the island in 1940 . However, rats occur on a small island only a few hundred metres from Ua Huka, therefore without adequate preventative measures the probability of rats being introduced onto Ua Huka is high.
The first stage of the proposed study will be to determine the presence, distribution and density of rats and any other competitors and predators on each of the Marquesas Islands within the lorikeet’s range. The current population status and distribution of V. ultramarina will be determined by conducting systematic surveys on all relevant islands. Habitat use and location of nesting sites will be determined from these surveys and additional searches. Nesting sites will be identified, mapped and monitored to assess nesting success. Based on these assessments, baiting of rats will be initiated around active breeding trees and in areas of particularly high rat density. Trimming of branches of active nest trees and placement of protective guards around the bases of nest trees will prevent rats from climbing to nests. These methods have been successfully employed for the recovery of critically threatened species in the region (e.g. Tahiti flycatcher). Supplementary rat-proof nest boxes will be placed in suitable habitat on Ua Pou and Nuku Hiva to encourage nesting. Given the current rat-free status of Ua Huka a high priority will be rat baiting around the harbour landing. All these measures should help stabilise or increase lorikeet numbers and also be of benefit to other critically endangered species on the islands. The success of the mitigation measures proposed will be assessed by post-breeding season urveys and monitoring of nesting success.
This immediate conservation effort will be complemented by a larger scale program which will include determining the practicality of various rat eradication programmes on the infested islands as have already been implemented in Tahiti and elsewhere in the Pacific. In this respect, priority will be allocated for a rat control or eradication programme on Fatu Hiva where R.rattus have only recently been introduced. Additionally, a program to raise local awareness of the rat problem will be initiated given the health and agricultural problems caused by rats. We will also work with schoolteachers to make children proud of their island birds. Should this program be successful it could be extended to other islands where scarce populations of Vini still exist, particularly the endangered Vini kühlii on Rimatara.
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