Artificial micro-habitats

Definition

Artificial micro-habitats are purpose-designed structures integrated into buildings and infrastructure to provide small-scale shelter, refuge, or breeding opportunities for biodiversity where natural habitat is limited.

What this strategy does

This strategy introduces targeted habitat features, such as: nesting boxes; invertebrate hotels; façade-integrated recessions, ledges, or niches; gabion walls (for lizards and insects); and biodiversity tiles (in seashore environments for aquatic life), as well as any eco-engineered elements integrated into built environments to support specific species. These might include strategically using shaded and sunny sides of buildings to create habitat niches.

Designers should avoid generic or poorly located features that function as ecological traps or provide no long-term benefit. Ecological traps occur when animals are attracted to habitats that appear suitable but are actually poor quality or harmful, reducing their chances of survival or reproduction.

Context (Aotearoa New Zealand)

In dense urban environments across Aotearoa New Zealand, vegetation cover and natural cavities are often scarce. Artificial micro-habitats are most relevant where biodiversity outcomes must be delivered through buildings and infrastructure rather than land-based restoration.¹, ²

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Technical considerations

Design considerations

Habitat diversity

• Provide a variety of cavity sizes, surface textures, and habitat types, arranged with some variation in spacing and clustering (moderate patchiness). This helps support more species and prevents any one type of species (taxon) from taking over.¹, ²

Structural complexity

• Incorporate surface roughness, recesses, and three-dimensional features to increase niche availability across taxa, particularly on façades and hard infrastructure.³, ⁴, ⁵

Thermal and microclimatic performance

• Design for variation in solar exposure, shading, and moisture to create thermal refuges and improve occupancy and breeding success for different species.³, ⁶

Connectivity and placement

• Locate micro-habitats near vegetation or within dispersal distance of other habitat features to reduce fragmentation effects and improve functional use.², ⁷

Construction considerations

• Carefully design any building-integrated habitat features so they do not compromise structural integrity of buildings over time.

Implementation considerations

Species fit

• Match dimensions, materials, height, and orientation of habitat features to the requirements of locally occurring species. Use relevant regulatory guidance.⁸, ⁹

Vegetation integration

• Integrate native and structurally diverse planting around micro-habitats to improve habitat quality and support soil and invertebrate communities.¹⁰

Maintenance requirements

• Plan for regular inspection, cleaning, and replacement to prevent parasite build-up, overheating, and material degradation.⁶

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Issues & barriers

Ecological traps

• Poorly designed or poorly maintained structures may attract species while reducing fitness or reproductive success.¹¹, ¹²

Species bias

• Artificial habitats may disproportionately benefit adaptable or invasive species if design and placement are not carefully targeted.¹¹, ¹³

Ongoing management

• Regular maintenance is required to sustain ecological function, which can be overlooked in long-term asset management.⁶

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Synergies & opportunities

• Climate change – Provides thermal refuges that support species persistence under increasing temperature extremes.¹⁴, ¹⁵
• Human wellbeing – Visible habitat features can enhance everyday connection to nature in urban settings.¹⁵

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Financial case

Urban resilience and amenity

• Biodiversity-supportive design can contribute to microclimate regulation, amenity value, and long-term urban resilience.⁸, ¹⁶

Cost-effectiveness: Low-cost targeted intervention

• Simple habitat structures are relatively low-cost interventions with high educational and engagement value when correctly designed.¹⁶

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Monitoring & evaluation metrics

Core metric

• Occupancy and breeding success of target species can be assessed through routine inspections and monitoring.¹¹, ¹²

Advanced metric

• Species richness and composition can be assessed using multiple diversity metrics, supported by citizen science or remote sensing where appropriate.¹⁷, ¹⁸, ¹⁹, ²⁰

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Additional resources or tools

• Department of Conservation – Build a wētā motel. Practical guidance for constructing invertebrate habitat features
• NUWAO – Nature-based Solutions Design Guide for Te Moananui Oceania. Design guidance for nature-based solutions.
• WSP – Urban Greening Tool. Tool for assessing and comparing urban greening interventions.

References

1. Cacabelos, E., et al. (2018). Patchiness in habitat distribution can enhance biological diversity of coastal engineering structures. Aquatic Conservation, 28(5), 1161–1174.
2. Garrard, G. E., et al. (2018). Biodiversity sensitive urban design. Conservation Letters, 11(2).
3. Bishop, M. J., et al. (2022). Complexity–biodiversity relationships on marine urban structures. Philosophical Transactions of the Royal Society B, 377.
4. Collins, R., et al. (2017). The value of green walls to urban biodiversity. Land Use Policy, 64, 114–123.
5. Roux, D. J., et al. (2016). Nest box occupancy and design considerations. Forest Ecology and Management, 366, 135–142.
6. Maziarz, M., et al. (2017). Microclimate in tree cavities and nest boxes. Forest Ecology and Management, 389, 306–313.
7. Lindenmayer, D. B., et al. (2016). Nest boxes and hollow-dependent fauna. Restoration Ecology, 24(2), 244–251.
8. Varshney, K., et al. (2024). Biodiverse residential development in New Zealand. Urban Forestry & Urban Greening, 92.
9. Goldingay, R. L., et al. (2015). Nest box designs and habitat restoration. Restoration Ecology, 23(4), 482–490.
10. Mills, J. G., et al. (2020). Urban revegetation and soil microbiota. Restoration Ecology, 28(6), 1496–1505.
11. Griffiths, S. R., et al. (2017). Bat boxes are not a silver bullet. Mammal Review, 47(4), 261–265.
12. Sudyka, J., et al. (2021). Nest boxes and reproductive ecology. Journal of Avian Biology, 52(2).
13. Jagiello, Z. A., et al. (2022). Urban nest design and fitness. Science of the Total Environment, 838.
14. Scheffers, B. R., et al. (2014). Microhabitats and climate extremes. Global Change Biology, 20(2), 495–503.
15. Schmidt, K., & Walz, A. (2021). Ecosystem-based adaptation in urban environments. One Ecosystem, 6.
16. Box, J. (2011). Building urban biodiversity through incentives.
17. O’Shaughnessy, K. A., et al. (2023). Diversity metrics in urban environments. Science of the Total Environment, 876.
18. Belaire, J. A., et al. (2022). Fine-scale biodiversity monitoring. Science of the Total Environment, 806.
19. Finizio, M., et al. (2024). Remote sensing for urban biodiversity. Remote Sensing, 16(23).
20. Callaghan, C. T., et al. (2020). Citizen science for urban biodiversity monitoring. Biological Conservation, 251.