Wetland restoration work protects critically endangered bird
An ongoing restoration project is underway at Te Rauakaaka, near the mouth of the Waimakariri River, to enhance wetland and coastal ecosystems, boost biodiversity, and create vital habitat for endangered species – including the critically endangered matuku-hūrepo Australasian bittern, which our regional parks and forests team is backing for Bird of the Year.
Funded through the Christchurch/Banks Peninsula Biodiversity Targeted Rate, the project involves a suite of initiatives to expand and restore wetland and coastal forest habitats, helping to strengthen ecological resilience in this important area.
Expanding habitat for rare species
Situated on the south side of the Waimakariri River where it borders the Kainga, Stewart's Gully and Brooklands communities, the 212-hectare wetland site contains regionally-significant saltmarsh and freshwater wetland habitats.
A key focus of the restoration work is expanding raupō and other wetland plants, building on several successful trials. This will provide more habitat for native bird species such as the critically endangered Australasian bittern, a secretive wetland bird that is more often heard than seen.
By removing exotic grasses and enabling tidal flows to move further inland, the project will also expand īnanga spawning areas and improve overall biodiversity. Supplementary planting will be carried out alongside natural regeneration, while ongoing weed management will keep invasive species like willow, alder and yellow flag iris in check.
We're removing exotic grasses, which enables tidal flows to move further inland, expanding inanga spawning areas and improving overall biodiversity
Regional Biodiversity Officer - Rivers, Brad Smith said the work represents a major step forward for restoring native ecosystems at the Waimakariri River mouth.
“The current 14-hectare project area contains a mix of degraded habitats, but by carefully managing weeds and re-establishing native species like raupō, we’re expanding this thriving wetland so it can support critically endangered birds and other native wildlife,” Brad said.
“It’s a really exciting project because it shows how we can use science, community support, and targeted investment to bring our wetlands back to life.”
Using science to inform wetland restoration
The project design is based on both modern technology and traditional fieldwork. Aerial imagery and elevation analysis were used to identify historic wetland pockets, while on-the-ground surveys confirmed the presence of remnant wetland species such as juncus.
From these findings, a 7,000 square metre expansion area has been designed, including shallow low-lying areas that offer ideal conditions that we can deliberately clear of weeds, encouraging wetland plants to naturally regenerate. The next step will be creating hydrological connections between these areas and the central wetland, helping the ecosystem function as a larger, more resilient whole.
Supplementary planting will be carried out, while ongoing weed management will keep invasive species like willow, alder and yellow flag iris in check
Long-term values supported by wetland regeneration
The long-term outcomes of the work include:
- increased wetland habitat to support species such as the Australasian bittern
- expanded īnanga spawning areas
- enhanced terrestrial biodiversity through new pockets of coastal forest
- ongoing natural regeneration supported by weed control.
“Wetlands like Te Rauakaaka are a taonga within our region; they improve water quality, support mahinga kai, and provide food and shelter for countless native species,” Brad said.
“This work is about restoring those values, building resilience into our ecosystems, and ensuring that rare species like the bittern have a fighting chance.”