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Biosecuring Rimatara

R
imatara is the last black rat free island in the Australes archipelago.


RIMATARA ISLAND, THE LAST CHANCE FOR THE ‘URA

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The colonisation of black rats on this island would lead to the certain death of the only French Polynesian population of ‘Ura , or Kuhl’s Lorikeet (Vini kuhlii). It would also affect the Oroma’o, or Rimatara Reed-warbler (Acrocephalus rimatarae), which is endemic to Rimatara.
These birds not only hold heritage significance but can also help supporting a sustainable economic development through an ecotourism activity like birdwatching.

THE BLACK RAT: A THREAT AT MANY LEVELS


The invasion of the black rat on the Island of Rimatara would have a major impact on coconut plantations. Rats are good climbers and create extensive damage to coconuts. The monitoring of various rat-infested islands showed an average crop loss ranging between 20 to 80%. This loss can increase up to 90% at low altitudes and during the dry season . Financially, a 50% croploss would result in a loss of 105 000 euros per year in revenue for the inhabitants of Rimatara.

As for human health, the black rat is a vector of the leptospirosis bacteria, and a dangerous one at that, since it is not afraid to venture into homes. It’s difficult to differentiate the symptoms of leptospirosis from flu or dengue fever. Leptospirosis is potentially lethal if not prescribed quickly with antibiotics, and it actually kills a few people each year on rat infested islands.


ACTIONS UNDERTAKEN
Our preventive work (actions listed below) is conducted by an independent worker, with the help of the local community-based group and a sponsor. He received a specific training from the Polynesian Ornithological Society (SOP), which oversees the progress of the program and organize on-site visits twice a year.

Tiraha Mooroa (on the right) is in charge of the biocontrol in Rimatara. Etera (on the left) helps him from time to time.


Rat control on the wharf of Rimatara
To prevent any invasion of rats on the island, several bait stations with rodenticide have been set up on the docks. Tiraha renews the poison for each station on a regular basis and makes sure that the population is aware of their location and purpose.

Freight inspection
Every box arriving on the inter-island cargo Tuhaa Pae is inspected for any hidden rats. Tiraha has to reject any box that appears suspect.

Quarantine
The idea is to create a closed area, containing several rodenticide stations, where voluminous objects such as cars, cinder blocks, pipes or used coprah bags would be locked up for one week, leaving enough time for potential hidden rats to be eradicated before they could scatter across the island.
Moreover, this measure could be extended to other pests such as invasive insects like the Little fire ant. Tahiti is now ant-infested, causing serious damage to its avifauna and plantations, with few biosecurity measures taken regarding exports.
MANU (SOP) has conducted a public opinion poll of the quarantine project in Rimatara. The overwhelming majority of the population was in favor, and the local government agreed to provide premises. The quarantine shall be placed under the responsibility of the Town Council, as soon as the proposition is adopted by the Council of Ministers. We are currently establishing a legal framework for this quarantine, with the support of the High Commission. Conventions are in the making.

Trapping on a regular basis to verify the absence of black rats

Picture 1 : Little Polynesian rat (Rattus exulans). You can see a black line on the tarsus of its hind legs, which is a typical feature for that species.

Picture 2 : Rattus norvegicus aka Brown rat (present on Rimatara) is a big rat but its tail does not exceed the length of his body. When folding its ears over its eyes, they do not reach the latters.

Picture 3 : This is a Black rat. As you can see, its tail is longer than its body length.

These pictures were taken in Tahiti.

Developping an ecotourism activity
The SOP is training a guide, Tiraha Mooroa, to promote the ornithological beauties of this destination, amongst which the Lori is quite remarkable.

Check out the “Birdwatching trips” link for more information.


Gathering a community-based action group
This group meets twice a year.

Awareness-raising efforts in school
The program has been introduced in every school around the island, touching a hundred of kids.

Communication medium
Brochures have been edited for the crewmembers of ships stopping over.

Enhancing crew awareness and biosafety skills

The SOP is planning a training session for crewmembers of every cargo ship. It will include :

  • where to set up the anti-rodent device ;
  • how to set up rodenticide stations on board ( in goods storage areas )
  • recommendations on installing rat guards on all mooring lines to avoid rats getting onboard (while landing on infested islands)


RESULTS

Rimatara remains free of Black rats at the moment (none trapped yet).


SPONSORSHIP AND GRANTS

This biosecuring project was realized through grants from the BEST (European Union) and the Critical Ecosystem Partnership Fund). Another grant came from the TE ME UM (TErre et MEr UltraMarines) in 2013, which panel board comprises 17 members: RNF, WWF, French committee of UICN, Aten, PNF, LPO, ONF, Littoral conservation, Fondation Nicolas Hulot, FPNRF, ONCFS, FCEN, AAMP, Rivages de France, FCBN, MEDDE and MOM.

SUPPORTS

We want to acknowledge the support of the Regional Department of Environment (DIREN), the local council of Rimatara, and the Pacific Invasive Initiative. We would like to thank all those who helped us in anyway, especially the members of the community-based action groups and of course, the population of Rimatara for its warm welcome.