How Island Conservation Achieved Rat Eradication On
Wallis Islets
With Envico's Drone Baiting Technology
Project Location
Wallis Islets, Pacific Islands
Pest Species
Black Rat (Rattus Rattus) and Polynesian Rat (Rattus Exulans)
Client
Island Conservation California, USA
Services Deployed
Envico Aerial Drone Baiting
Envico Aerial Drone Thermal Imaging
Envico Expert Solutioning
Background
Island Conservation is a science driven non-profit organization on a mission to prevent extinctions by removing invasive species from islands.
To date, Island Conservation have successfully restored 65 islands worldwide, benefiting 1218 populations of 504 species and subspecies.
Working together with local communities, government management agencies, and conservation organizations, they select islands that have the greatest potential for preventing the extinction of globally threatened species and bring together expert project teams to deliver solutions.
Problem Snapshot:
The devastating destruction caused by rats
The environmentally valuable and idyllic islets in the French Territory of Wallis and Futuna, had become overrun with invasive rats.
“In our eyes, Island Conservation is a true hero organisation. They live and breathe their mission and are expert at enlisting and coordinating the right resources in order to achieve successful project outcomes.”
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Cameron Baker, CEO & Co-founder of Envico Technologies.
As well as being important breeding grounds for endangered species of birds and turtles, the islets also hold immense cultural significance for the local communities.
The rats were destroying the biodiversity of the islets, killing young native animals and stealing and eating the eggs of nesting birds and turtles.
"Here in Wallis, we have the perfect example of an area where biodiversity is being threatened by introduced species such as rats.”
Baudouin des Monstiers, Project Manager for Island Restoration at Island Conservation.
Rats: One of the most invasive species on earth
Rats are considered to be one of the world’s worst invasive and destructive species. As omnivores, rats have the ability to eat and survive on both plant and animal matter. This means much of the world’s native wildlife and fauna are on their meal hit list and protecting biodiversity becomes paramount.
A small population of rats can become a massive population in a very short time.
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Rats reach sexual maturity after just nine weeks, and have six litters each with 5-10 pups each year. This means an invasive rat population can swell from two rats to 1,000 in less than a year.
The rat crisis on Wallis islets: Why should we care?
The beaches on some of the Wallis islets are nesting sites for the Green Turtle (Chelonia mydas) and the Hawksbill Turtle (Eretmochelys imbricate). These creatures have roamed our oceans for more than 100 million years and both are now sadly endangered.
As the only herbivorous marine turtle, green turtles feed almost exclusively on seagrass and algae. As they graze the seagrass beds, the turtles increase the seagrass’ health and productivity (a lot like how mowing your lawn stimulates healthy grass growth). Green turtles quickly digest seagrass which then becomes available as recycled nutrients for the many species of the seagrass ecosystem.
Those same seagrasses absorb carbon and are one of the key “blue carbon” ecosystems helping us in the fight against climate change.
The ever increasing population of rats on Wallis islets became the key predator of the native vertebrate and invertebrate species on the islets, eating the eggs of native species and killing native juveniles.
Bringing together expertise to solve a challenging problem
Successfully completing complex missions such as this, does not happen by chance. Extensive expertise, planning, preparation and collaboration is required to arrive at a strategy which can deliver maximum impact.
In 2021, Island Conservation issued a Request for Proposal (RPF) as it sought to build an expert team to rid the Wallis islets of rats and return these special lands to native species and the local communities. Envico was selected as Island Conservation’s technology partner for the project.
Island Conservation excels at selecting the right partners for each of their projects and embraces the opportunities that new technology brings to the conservation space.
Some Wallis Island islets have rough vegetation, thick foliage and steep coastlines, which makes hand baiting impossible. Envico’s Aerial Drone Baiting Technology was employed for the project, enabling the project to be conducted at scale and pace.
Specialist drones enable large areas of land to be baited effectively and Envico has developed unique specialist drone spreaders for bait dispersal patterns. The spreaders attach to Envico’s drones which have been designed and built specifically for aerial baiting.
Technology for success
The drone used for this project, was a bespoke Envico custom drone with a 22-pound (10-kilogram) payload (load capacity) - the ENV10.
Due to the difficult terrain on the islets, Envico determined that a barge could be used as the drone landing base. This would enable the drone landing site to be positioned as close as possible to each islet, enabling a continuous line of sight of the drone and for flying time to be maximized.
Envico conducted an aerial baiting operation feasibility survey on the selected Wallis Islets. Communication plans were prepared and risks and hazards identified.
Using drone photos and GPC (ground control points) a 3D model was created, which provided a general spatial overview of the islets. Flight missions were then pre-programmed.
Island Conservation selected the rodenticide, Brodifacoum (Pestoff 20R Brodifacoum Orillon lab, and Bell Lab 25W Conservation) for the Wallis islets rat eradication project.
Activation: When plans transform into energy
The selected Wallis Island islets received two applications of Envico aerial drone baiting. A three week stand down period between bait timings was used to allow for juvenile rats (pups) to be targeted that may have been missed during round one. Each application round took three weeks.
Each single flight took approximately 2.5 minutes with an average drone speed of 6MPS (meters per second) - the equivalent of 21 kph.
Envico’s bait dispersal deployment is extremely quick, occurring in a time span of just 30 seconds during each flight. A 25kg ph (per hectare) application rate was used.
Envico’s custom bait dispersal drone technology provides for a dispersal range of 35 metres either side of the drone.
An overlapping approach was taken for the Wallis project to ensure full coverage using a 50% overlapping methodology.
Results: The consequences of our actions
The Wallis islets aerial drone baiting project was deployed in July and August 2022. Results reporting was conducted in February 2023.
"The project in Wallis and Futuna, is Island Conservation’s most ambitious innovation project to date. Each of the atoll’s small islands presented unique geographical and environmental conditions to navigate.”
Island Conservation.
Heavy-lifting drones such as Envico’s ENV10 can be an ideal solution for completing complex operations on islands. Traditionally helicopters have been used, which can be cost prohibitive and require far more time and resources.
Five of the seven Wallis islets which received the drone aerial baiting were reported on for results tracking by the client.
By February 2023, Island Conservation reported that all five reporting islets were confirmed as rat free.
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Follow up reporting was conducted on the five islets in December 2023, approximately 16 months after the aerial drone baiting project was implemented. Island Conservation confirmed that once again, all five islets remained rat free.
"This was one of our most successful drone-powered restoration campaigns.”
Island Conservation.
Outcomes
Positive feedback has been reported by village chiefs and the Wallisian population regarding the benefits of the operations.
Improved harvests of fruit trees and coconut groves were reported; a greater abundance of coconut crabs, and better survival conditions during turtle hatching.
A monitoring of noddis (birds of the Laridae family) implemented since 2023 by the Caledonian Society of Ornithology on the islets that were de-ratted, has also shown an increase in the abundance of the populations of these birds.
Why Envico?
Envico’s core competencies are in specialist drones and automated systems, particularly targeting invasive pest animals.
Island Conservation had partnered with Envico on previous projects, so they had personal experience of Envico’s industry leading capabilities in the drone conservation technology space.
Perhaps what positions Envico as the world’s leading conservation technology partner though, is their focus on delivering a complete holistic solution.
With an offering that includes thermal imaging, aerial drone baiting for large scale pest eradication, effective smart trap devices for land-based pest knock downs and reduced incursions, as well as drone seed pod technology for fauna regeneration - all wrapped up with Envico’s expert guidance - Envico enables their partners to achieve greater outcomes.
"As we move forward, we are excited about the limitless potential that drone technology offers.
Our commitment remains steadfast: to restore islands faster, cheaper, and safer, thereby protecting biodiversity and ensuring a healthier planet.”
Island Conservation.
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