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 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.
Tiraha Mooroa (on the right) is in charge of the biocontrol in Rimatara. Etera (on the left) helps him from time to time.
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.
Check out the “Birdwatching trips” link for more information.
The SOP is planning a training session for crewmembers of every cargo ship. It will include :
Rimatara remains free of Black rats at the moment (none trapped yet).
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.
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.