Ua Huka is the last of the inhabited islands in the Marquesas archipelago still free of black rats. The introduction of the black rat would mean the end of two endemic birds: the Pihiti a.k.a. ultramarin Lorikeet (Vini ultramarina) and the Pati’oti’o a.k.a. Iphis Monach (Pomarea iphis). The Pihiti used to be present on other marquesian islands aswell: Nuku Hiva, Ua Pou, Tahuata, Hiva Oa and Fatu Hiva (reintroduced in the 90’s). The black rat is also the prime cause for the disappearance of Mornachidaes.
The last chance for Pihiti and Pati'oti'o
These birds not only hold an important heritage significance but they can also be of great help supporting a sustainable economic development in Ua Huka, through an ecotourism activity like birdwatching.
Outre leur importance patrimoniale, ces oiseaux ont une importance éco-touristique majeure pour le développement de Ua Huka.
The black rat : a threat at many levels
The colonisation of black rats on the Island of Ua Huka 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 from 20 to 80%. This loss increases up to 90% at low altitudes and during the dry season, as rats drink coconut water. Financially, a 20% and 50% croploss would respectively result in a loss of 48 000 and 105 000 euros per year in revenue for the inhabitants of Ua Huka. These numbers have been computed using the coprah industry data for the past three year.
As for human health, the black rat is a carrier of the leptospirosis bacteria, and a dangerous one at that, since it is not afraid to venture into homes. Leptospirosis is lethal if not prescribed quickly with antibiotics, actually killing a few people each year on rat infested islands.
Nos actions
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.
Photo: Geoffray Sulpice training for rat trapping
His sister Hinapootu Sulpice also helps with trapping
To prevent any invasion ot rats on the island, several bait stations with rodenticide have been set up on the docks of Vaipahe and Hane. Geoffray renews the poison for each station on a regular basis and makes sure that the population is aware of their location and purpose.
Every box arriving on the inter-island cargo ships, Taporo IX and Aranui, is inspected for any hidden rodents. Geoffray has to reject any box that appears suspect.
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. This would leave enough time for potential hidden rats to wend their way out of the freight and 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 apparently no biosecurity measures taken regarding exports (presence of insects observed in the freight).
MANU (SOP) has conducted a public opinion poll of the quarantine project in Ua Huka, and all were in favor. The association identified a location that would be suited for quarantine.
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 (absent on Ua Huka) 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.
The SOP is training two guides, Geoffray Sulpice and his sister Hinapootu, to promote the ornithological beauties of Ua Huka, amongst which the Lori is quite remarkable.
Hit the “Birdwatching trips” link for more information.
The population of Ua Huka holds this project closely to its heart.
Awareness of the black rat threat for their unique avifauna has been raised amongst over 200 adults, and the community-based action group has been particularly active.
The awareness campaign has just been launched.
Brochures have been edited for the crewmembers of ships stopping over.
To improve the contaiment of black rats, the SOP proposed a panoply of actions to the crewmembers of the two cargoships serving Ua Huka, Aranui III and Taporo IX.
The plan is to decrease the risk of rats getting off the boats, through :
- setting up anti-rodent devices on docks and onboard ( in goods storage areas );
- installing rat guards on all mooring lines to avoid rats getting on and off the boart;
- renewing the rodenticide every month;
- training the crew on the matter of biosecurity.
Through sponsorship, the SOP has been able to offer anti-rodent devices, rat guards and posters to their contacts in Ua Huka. So far the plan is being followed.
We have established contact with these two entities in order to reduce the rodent population on the docks of Papeete, especially near the ships serving Ua Huka and Fatu Hiva ( Taporo IX and Aranui III ).
Three solutions have been considered in concertation with the Autonomous Port authority:
- use of anti-rodent devices;
- set up a network of bait stations containing rodenticide renewed every month;
- synchronization and follow-up of the rat-control teams operating on the docks.
The Huilerie de Tahiti needs to improve the management of its used coprah bags, and stop sending them to islands with no inspection. The sacks need to be either put in a container for cyanide acid treatment or in a room with anti-rodent devices to get rid of rats before shipment.
Results
For now, no rats have been trapped in Ua Huka and the biosecuring plan seems well on track.
Sponsorship and grants
This 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, French coastal protection agency, Nicolas Hulot Foundation , 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 Ua Huka, and the Pacific Invasive Initiative (PII). 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 Ua Huka for its warm welcome.