Phase 1 (2022–2025): Operational Trials & Research

Rationale

Waiheke Island (population 9,400; 92 km²) presents a distinct challenge for rat eradication due to its varied terrain and land use. Techniques for removing rats from rural settings like forests and open land are well established, but strategies for urban environments are less developed.

Social and economic research plays a vital role by enriching the trials, offering a deeper understanding of both the island and its community.

Key Objectives

Test eradication tools and methods in different environments
Understand community attitudes and concerns
Evaluate the cost-effectiveness of island-wide eradication

i) Urban Rat Trials- Key Findings

🧪 Technical Research

Location	Key Questions		Key Findings
Kennedy Point (2022)	Can traps alone remove rats?	Traps help control but can’t fully eradicate.
Ostend (2022)	Can bait stations remove rats in commercial areas?	Weekly serviced 25x25m bait station grids are effective.
Mangroves	Can floating bait stations work?	Yes, specially designed stations are effective.
Oneroa (2023)	Can bait stations work in residential areas?	Yes, a network of bait stations serviced weekly can quickly knock down rats to ver low number, bu tan extended period of 'detect and respond' using multiple tools is needed to catch the last few rats.
Surfdale (2024)	Can methods be refined and confirmed?	Yes, Oneroa findings were confirmed. Intensive monitoring is needed (including cameras) to detect and remove all remaining rats after the initial knockdown. Bait stations, different types of bait, and traps are ALL needed to remove the last rats from an area. It would be extremely difficult to protect a perimeter without rats being removed from all areas of the island at the same time.

ii) Preliminary Rural Trials (Planned 2025)

Internationally and nationally, there are many examples of successful eradications in rural areas, using bait distributed outside bait stations, and a mountain of knowledge exists. These small trials on Waiheke are therefore designed to ‘ground truth’ existing methodologies in the specific Waiheke context. Trials will involve non-toxic bait distributed via drones and controlled hand distribution.

Key questions

● Establish the cost per hectare of drone and hand broadcasting of bait as an eradication methodology.

● Add knowledge base of the potential impact of bait on non-target species.

Phase 2: Consolidation

Island eradications of all scales and complexities require precise and rigorous planning, and Waiheke is no exception. Once the tools and techniques required have been established from Phase 1, an in-depth plan will outline exactly how and where these tools would be deployed in an eradication.

Project Plan

The plan will include, but not be restricted to :-

A clear definition of Project Goals
Logistical considerations for planning and managing rat eradication
A plan of how non-target species (incl. household pets, stock, and native fauna) will be protected.
A comprehensive plan for ensuring public safety
How staff will be recruited and trained
A detailed budget

Biosecurity Plan

A biosecurity plan will also be developed detailing how the risk of reinvasion will be managed once island-wide rat eradication has been achieved. This will again include, but not be limited to:

Identifying the main pathways for reinvasion
A Plan for preventing reinvasion via these pathways
A Plan for ongoing monitoring and surveillance
The methods used for responding to incursions

Engagement and consultation

Extensive communication will be undertaken with all landowners and/or tenants to gain permission to operate on their property, with the opportunity given to establish specific operational requirements for each property.

Phase 3: Fundraising

We are confident that the benefits of a full eradication will far exceed the costs. However, carrying out an island-wide rat eradication will require substantial additional funding beyond our current partner contributions. Once the project’s feasibility and total cost are confirmed, a targeted plan will be developed to secure the necessary support from companies, individuals, and trusts.

DECISION: ERADICATION GO AHEAD OR POSTPONE

Phase 4: Planning

Building on the Project Plan developed in Phase 2, this phase will focus on translating the framework into a fully operational plan. It will incorporate all the necessary details required for implementation, including a comprehensive timeline, specific site locations, assigned personnel, training requirements, safety protocols, and logistical considerations.

This level of detail will ensure the project is ready for execution with clarity and efficiency.

Phase 5: Eradication and no more rats!

💬 Social Research

Rat eradication
What is the level of support for eradicating rats from Waiheke?	On average, 98% of Waiheke residents support eradicating rats from the island
Eradication tools and methods
What are community views on eradication tools and methods?	Waiheke residents hold a spectrum of views on rat eradication with concerns about toxin use and ecological impacts being key factors.
Under what conditions should eradication tools and methods be used?	Predator eradication approaches need to be designed to fit local conditions and landowner/tenant needs while minimizing perceived risks to native species and the environment
Dog owners
Are dog owners concerned about using bait?	Most dog owners support using bait in enclosed stations,
	Owners generally emphasize responsible pet practices (leashes, fencing)
Recreational boaties
How big a risk are recreational boat owners for accidentally bringing rats to Waiheke?	Larger boats (>6m) generally stay in Auckland marinas where there is rat control while smaller boats (<6m) are stored on residential properties, mostly without any rat control
	Most boaties clean their boat frequently, meaning they could detect rats early

💰 Economic Research

Question	Findings
Are the benefits greater than the costs?	Yes – projected $249.9M net benefit over 50 years.
Estimated Costs	$43M for eradication + $72.9M total with biosecurity over 50 years.
Key Benefits	• Doubling of bird populations • Boost to ecotourism ($20.1M value) • Increased agriculture productivity ($26.7M) • Saved pest control costs ($22.1M)

The Rat Eradication Roadmap