Defining metrics of success for feral animal management in northern Australia

In northern Australia, there is growing recognition of the importance of wetlands to biodiversity and ecosystem health, along with their cultural value to Indigenous communities. Feral pigs and cattle pose significant threats to wetland system ecology and biodiversity through negative impacts on wetland vegetation assemblages, biological communities and water quality.

In this project, we quantified the impact of feral species on wetland condition, the effectiveness of control measures on mitigating the threats to aquatic systems, and the subsequent impact on cultural wetland values. To do this, we defined, evaluated and calibrated metrics used to describe the impacts.

To capture the complexity of metrics that describe both biophysical and cultural impacts of feral pig management, a collaborative team of ecologists, human geographers, Traditional Owners and land managers developed an integrated monitoring and reporting framework to monitor and report on wetland biophysical values with cultural ecosystem services research. The framework, which strongly emphasises embedding cultural values and supporting Indigenous-led management and planning, enables the comparison of investment in control, with consequent impacts on environmental values.

The project had five general components:

• aggregation of an extensive baseline data set for Queensland’s Archer River basin to assess change under future investment strategies
• generation of new wetland/waterhole typologies for the Archer River basin to support modelling of the spatial and temporal distribution of feral pigs
• development of a cultural ecosystem service wetland typology to support wetland management on Wik Peoples’ traditional lands
• cost–benefit analysis of selected control methods for feral pigs
• development of a reporting system for assessing the impact of feral pig management on aquatic systems.

Project outputs can be used by land managers to identify priority wetlands for targeted management while providing a means to evaluate the impact of current feral species management. The monitoring methodologies are replicable and allow land managers to review change over time. The establishment of new wetland typologies supersedes old typologies that didn’t support the modelling of feral pig data and omitted cultural values. Cost–benefit analysis of select control methods for feral pigs enables the comparison of investment against impacts, supporting better future decision making for land managers.

This research took place in the Archer River basin in north Queensland but the adaptive management framework proposed here can be used across northern Australia.

This project has delivered research outcomes that have led to direct changes to the way feral pigs and cattle are being managed across millions of hectares on Cape York Peninsula. Research partners have increased the baseline knowledge of feral pig impacts and management through the production of technical mapping products, software, monitoring tools and peer-reviewed journal articles.

The team has communicated these impacts through a variety of media and has delivered presentations and advice to a broad cross-section of stakeholders including government policy departments, land management organisations and conservation entities. Project outcomes are also supporting national initiatives for feral animal control.

This project identified that in the absence of purposeful, impact-driven management and monitoring, it was impossible to assess positive or negative change from landscape-scale feral pig control and limited benefits accrued for Traditional Owners and funders. However, when control was targeted and associated with clear metrics of success (e.g protection of marine turtles), management interventions were successful and sustained.

We recommend that control programs are targeted to enhance and protect defined values. For this to be effective, control needs to be paired with monitoring and assessment that tracks values with defined critical thresholds that reflect positive or negative change to values.

We developed wetlands monitoring and assessment tools which enable land managers to analyse and interpret baseline metrics of system health and identify priority wetlands for targeted management. The use of digital assessment and decision-support tools can provide vital information to land managers to enable them to undertake effective and robust control programs. The interactive dashboard provides a system that can be extended and modified by end-users to input and visualise data. This allows land managers to test the value of the data they are collecting for assessing impact on different values.

This research found that effective feral pig management requires the following elements:

• continuous and purposeful collaboration with land managers and/or Traditional Owners to clearly define the values that are being impacted and the desired outcomes that the management activities aim to enhance
• metrics of success must be tied to the values and outcomes that the program aims to enhance, i.e. monitoring of control impact should focus on measures of change in ecosystem, social and cultural values
• control actions need to be tailored to the differences in feral animal densities, alongside the values the program aims to enhance.

Through involvement of all key management groups, this project has fostered a shared understanding of the most effective and efficient ways to manage feral animals to deliver joint social, environmental and cultural benefits. This project has developed real-world solutions that can be practically implemented by land managers to support continued management of feral species.

The interactive dashboard aggregates the project data into an accessible interface.

Feral animals such as pigs negatively impact terrestrial invertebrates, freshwater turtles, marine turtles and freshwater fishes. They directly prey on turtles and their nests, and modify habitats to impact the ecological function of waterholes. New methods for monitoring the changes in impacts at different scales can use readily available technology (mobile devices, off-the-shelf drones and cameras attached to helicopters). Several of these methods can be applied systematically by land managers working in similar ecological systems to support robust monitoring and reporting. The figure below describes a way to bring together various elements into an operational monitoring program.

Infographic showing suggested use of the methods discussed in the report. We suggest an adaptive management approach where baseline information is derived and then sites are monitored annually to report changes. Step 1: Desktop waterhole typology and management units mapping. Use waterhole typology mapping framework to map all waterholes in the management area. Select practical management units based on assessment of access, values, vegetation and impacts. Step 2: Waterhole typology mapping. Fly helicopter with GPS-enabled camera across the management areas to quantify and categorise waterhole types and impacts. Step 3: Select monitoring sites. Choose sites that reflect impacts, values and waterhole types. Select three (ideally five) sites in each type to account for variance within types. Step 4: Survey the selected sites. Using a drone, collect detailed aerial photos of each waterhole – fly at 50 m altitude, use photogrammetry software to stitch images into a geo-rectified image. Step 5: Feral animal management operations. Undertake various management operations and collect detailed monitoring data (e.g. location, date, time, costs, effort and human resources). Step 6: Reporting and adaptation. Use HealthyCountryAI framework to create spatio-temporal reports visualised using interactive digital dashboards. Following management events, observe the trend in the values that are being monitored and alter management actions. Return to step 2 and start the adaptive cycle again.