Ecological islands / predator-free areas

Some of Aotearoa New Zealand’s ‘Mainland Islands’. Image from Sanders & Norten (2001).

Ecological islands, predator-free areas, conservation arks, biodiversity islands, mainland islands, or ecosanctuaries relate to a specific conservation strategy aimed at protecting vulnerable species from predation. Some ecological islands exclude humans and others do not. These areas are established to provide safe havens for certain species that are particularly susceptible to predation, often due to the introduction of non-native predators into an ecosystem (such as rats, possums, stoats, ferrets, and cats in Aotearoa New Zealand). Ecological islands can also address habitat loss or other human-induced pressures for specific species (Russell et al., 2015). These areas can literally be isolated islands where predators have been removed or can be fenced-off mainland areas where predators are actively managed or excluded.

In these predator-free zones, efforts are made to remove or control predators that threaten the target species. This can involve measures such as trapping, and eradication of non-native predators. By creating these predator-free spaces, target species may have a chance to recover and thrive.

Name of NbS

Ecological islands / predator-free areas

Type of NbS

Ecosystem restoration, Ecosystem protection, Management / social / political

Location

  • Urban
  • periurban, rural.

Ecological islands need to be separated from other spaces so often require large areas. There are examples of urban ecological islands such as Zealandia in Wellington, Aotearoa.

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Case Study

Birnie Island, Kiribati bird sanctuary

Predator-proof fence at Te Korowai o Mihiwaka Orokonui Ecosanctuary. Dunedin, Aotearoa New Zealand. Photo by Stephen Marks.

Relationship to Indigenous knowledge

The ecological islands concept can be traced to Western ideas of conservation, however, there are some strong intersections with Indigenous knowledges.
Indigenous peoples often possess deep knowledge of their local ecosystems, including the behaviour of plant and animal species, the dynamics of habitats, and sustainable resource management practices. In Te Moananui Oceania many local or Indigenous communities have designated certain restricted areas or have implemented practices that relate to the idea of protecting certain areas from practices that may degrade habitat or reduce biodiversity for various periods. Concepts include rāhui/rahui, ra’ui, tapu, and tabu. See customary resource management for further details of these Te Moananui Oceania concepts.

Many conservation organisations and government agencies now seek to collaborate with Indigenous communities to protect and manage biodiversity. By integrating Indigenous perspectives and practices into conservation initiatives, projects can benefit from a more holistic understanding of local ecosystems and their histories and therefore develop more effective strategies for biodiversity conservation and sustainable land management.Ecological islands and Indigenous knowledge are also linked because of cultural values and spiritual beliefs associated with the land/waters and their creatures in Te Moananui Oceania. Specific plants and animals are often thought of as being toanga (treasures), or sacred, or special in some way (Mihaere et al., 2024). Because predation-caused biodiversity loss tends to be a result of historic or ongoing colonisation there is an obligation for Governments to ensure that native biodiversity is conserved and valued. Biodiversity holds deep cultural significance, meaning conservation efforts not only protect biodiversity but also preserve cultural heritage, identity, and traditional ways of life in some areas. These concepts are discussed more fully in respecting Te Moananui interconnected living ecologies.

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Climate change benefits
  • Biomass cover loss
  • Changes in phenology (life cycle timing changes in plants and animals)
  • Increased pests or spread of weeds
  • Increased temperatures
  • Reduced air quality
  • Reduced soil quality
  • Reduced water quality
  • Urban heat island effect

Ecological islands can play a role in addressing climate change through several mechanisms. Healthy ecosystems, such as forests and wetlands, act as carbon sinks, absorbing and storing carbon dioxide from the atmosphere. Preserving or restoring these habitats enhances carbon sequestration. Ecological islands protect biodiversity by providing safe habitat. Biodiverse ecosystems tend to be more resilient to climate change impacts such as extreme weather events, temperature rises, and habitat loss. They can enhance the resilience of communities to climate change impacts. For example, coastal habitats like mangroves and salt marshes within ecological islands can provide natural buffers against storm surges and coastal erosion, protecting nearby human settlements from climate-related hazards.

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Societal / socio-cultural benefits
  • Biodiversity health and conservation
  • Climate change adaptation
  • Disaster risk reduction
  • Human physical health and wellbeing
  • Rights/empowerment/equality

Ecological islands can serve as focal points for community engagement and environmental stewardship. Involving local communities in the creation and management of ecological islands can build awareness and capacity for climate action, fostering a sense of ownership and responsibility for environmental conservation. Other social benefits accrue when people are able to enter ecological islands such as relaxation, recreation, and tourism opportunities. The clear links between human health and connection to nature, particularly forests are discussed by Karjalainen et al. (2010). 

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Ecological and biodiversity benefits
  • Biological control (regulation of pests and disease)
  • Climate regulation
  • Decomposition
  • Fixation of solar energy
  • Genetic resources (diversity)
  • Habitat provision
  • Pollination
  • Purification (of water, soil, air)
  • Soil building
  • Species maintenance

Much island archipelago biodiversity has changed dramatically as a result of human colonisation, which often comes with introduced pests and weeds. This is true in Te Moananui Oceania where high levels of endemic species are found, and high levels of biodiversity loss have been recorded. Pacific island flora and fauna are particularly vulnerable to invasive alien species, given the historical absence of mammalian predators, grazing herbivores and aggressive weeds (Jupiter et al., 2014). Many species have become extinct and a relatively large proportion of those remaining are threatened with extinction. The main causes of biodiversity loss are habitat loss and fragmentation and the ongoing impacts of introduced pests (Saunders & Norton, 2001). Ecological islands are a way to counter this biodiversity loss in contexts where introduced predators are a main cause of native species decline. Conserving biodiversity through providing safe habitats clearly has key ecological and biodiversity benefits, where all ecosystem services would be enhanced.

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Technical requirements

The effectiveness of ecological islands as predator-free areas depends on various factors, including the size and isolation of the area, the target species’ biology and behaviour, and the ongoing success of predator control measures. While they can be a valuable tool for conservation, they often require significant ongoing management and monitoring to ensure their success. Technical requirements are dependent on understanding the needs of target species and the behaviours of predators. The shape of conservation sites where terrestrial pests are being intensively managed may influence their defensibility against re-invasion (Saunders & Norton, 2001). Montagnini et al., (2022) discuss specific design considerations including configuration, size, and location in the landscape of ecological islands.

Issues and Barriers

In Te Moananui Oceania, establishing ecological islands encounters unique challenges. Fragmentation disrupts connectivity in many island ecosystems. There may be limited land to establish ecological islands on mainlands. Land use conflicts may arise due to competing interests like tourism and development. Climate change amplifies these issues, jeopardising coastal habitats and species in particular. Effective governance is crucial but faces hurdles such as limited funding and knowledge, and coordination among Pacific Island nations. Overcoming these challenges demands tailored strategies. Examples may include transboundary conservation agreements, community-led initiatives, and sustainable tourism practices.

Opportunities

In Te Moananui Oceania, ecological islands present opportunities for biodiversity conservation, cultural empowerment and identity building, and potentially sustainable livelihoods. By preserving unique island biodiversity, these initiatives may support ecotourism while supporting traditional practices, and Indigenous knowledge. Collaboration between Te Moananui Oceania nations and international partners may offer avenues for funding, capacity building, and knowledge exchange.

Financial case

Ecological island initiatives can attract ecotourism, generating revenue from visitors eager to experience unique island biodiversity and cultural heritage. This is seen at Zealandia in Wellington, New Zealand. Carbon offset programs may provide opportunities for revenue generation through carbon sequestration in restored habitats. Enhanced resilience to climate change through increased biodiversity and habitats can reduce the costs of adapting to impacts. Leveraging international funding mechanisms and partnerships can further bolster the financial sustainability of ecological islands which tend to require a lot of maintenance and monitoring.

Zealandia’s predator-proof fence, Wellington, Aotearoa New Zealand. Photo by Judi Lapsley Miller.
References
  • Jupiter, S., Mangubhai, S., & Kingsford, R. T. (2014). Conservation of biodiversity in the Pacific Islands of Oceania: challenges and opportunities. Pacific Conservation Biology, 20(2), 206-220.
  • Karjalainen, E., Sarjala, T., & Raitio, H. (2010). Promoting human health through forests: overview and major challenges. Environmental health and preventive medicine, 15, 1-8.
  • Mihaere, S., Holman-Wharehoka, M. T. O., Mataroa, J., Kiddle, G. L., Pedersen Zari, M., Blaschke, P., & Bloomfield, S. (2024). Centring localised indigenous concepts of wellbeing in urban nature-based solutions for climate change adaptation: case-studies from Aotearoa New Zealand and the Cook Islands. Frontiers in Environmental Science, 12, 1278235.
  • Montagnini, F., Levin, B., & Berg, K. E. (2022). Introduction. Biodiversity islands: strategies for conservation in human-dominated environments. In Biodiversity Islands: Strategies for Conservation in Human-Dominated Environments (pp. 3-37). Cham: Springer International Publishing.
  • Russell, J. C., Innes, J. G., Brown, P. H., & Byrom, A. E. (2015). Predator-free New Zealand: conservation country. BioScience, 65(5), 520-525.
  • Saunders, A., & Norton, D. A. (2001). Ecological restoration at mainland islands in New Zealand. Biological Conservation, 99(1), 109-119.