Definition
Animal movement infrastructure comprises purpose-built structures that enable wildlife, including fish, to move safely through human-modified landscapes, including roads, railways, waterways, and urban development.
What this strategy does
This strategy reduces habitat fragmentation by providing crossings, passages, and corridors that support safe movement and dispersal of wildlife. It avoids ad-hoc or poorly sited structures that do not connect suitable habitat or accommodate target species.
Context (Aotearoa New Zealand)
In Aotearoa New Zealand, many native freshwater species migrate as part of their life cycles, and terrestrial species also rely on connected habitats. Built barriers such as culverts, roads, and weirs can restrict movement, reduce genetic exchange, and contribute to population decline. Fish passage and wildlife crossing infrastructure are therefore critical components of biodiversity-sensitive design.
Technical considerations
Design considerations
Location and alignment
Locate structures where animal movement is known or likely to occur, such as riparian corridors, breeding routes, and access points to water.
Network integration
Align crossings with wider ecological networks, including reserves, riparian margins, and green infrastructure systems, to maximise functional connectivity.
Spacing and redundancy
Provide multiple crossings where feasible to reduce bottlenecks and accommodate different species, home ranges, and dispersal distances.
Habitat continuity
Ensure suitable habitat exists on both sides of the structure so crossings do not expose wildlife to predators or other hazards.
Implementation considerations
Avoidance first
Avoid introducing new barriers in waterways and landscapes wherever practicable; preventing fragmentation is more effective than retrofitting solutions.
Species capability
Design fish passage and crossings to accommodate the full range of swimming, climbing, or movement abilities of locally occurring species.
Regulatory coordination
Fish passage works are highly regulated and typically require early coordination with councils, iwi, and specialist agencies.
Assessment tools and standards
Use recognised guidance and tools, including those produced by NIWA and regional councils, to confirm functional movement outcomes.
Issues and barriers
Pollution and disturbance
Artificial lighting, traffic noise, and contaminants can reduce the effectiveness and use of movement infrastructure.
Ecological traps
Poorly sited structures may funnel wildlife into unsafe areas or fail to connect viable habitats.
Invasive species risk
Increased connectivity can unintentionally facilitate the movement of invasive species if not carefully designed and managed.
Synergies and opportunities
- Climate change – Maintaining connectivity supports species movement and adaptation in response to changing climatic conditions.
- Human wellbeing – Well-designed crossings can enhance visual amenity, safety, and opportunities for people to engage with nature.
Financial case
Ecosystem services and biodiversity value
Population resilience
Maintaining movement pathways supports genetic exchange, lifecycle completion, and long-term species viability.
Cost-effectiveness
Targeted investment
Wildlife crossings and fish passage interventions can deliver high biodiversity outcomes relative to cost compared with large-scale land acquisition or restoration.
Monitoring and evaluation metrics
Core metric
Use of movement infrastructure by target species can be assessed through camera traps, eDNA sampling, or spotlighting.
Advanced metric
Changes in habitat connectivity and movement patterns can be measured using GPS tracking or long-term monitoring across fragmented landscapes.
Case study
Oamaru Blue Penguin Underpass
Related design strategies
- Artificial micro-habitats
- Building-integrated vegetation
- Natural micro-habitats
- Maintenance for biodiversity
Additional resources or tools
NIWA – Fish Passage Assessment Tool (FPAT)
https://niwa.co.nz/freshwater/fish-passage/fish-passage-assessment-tool
NIWA – Fish Passage Guidance and Research
https://www.niwa.co.nz/freshwater/fish-passage
Ministry for the Environment – Freshwater Management Guidance
https://environment.govt.nz/acts-and-regulations/national-policy-statements/national-policy-statement-freshwater-management/