Canterbury boasts over 60 per cent of Aotearoa/New Zealand's rare braided river systems, nurturing diverse ecosystems under threat from various factors. Find out how our projects improve habitats for indigenous species in braided rivers.
Ecological and biodiversity value of braided rivers
The value of braided rivers: Braided river systems are a rare geological feature evident in only a handful of other countries. More than 60 per cent of Aotearoa New Zealand’s braided rivers are right here in Waitaha Canterbury. These unique river systems support a vibrant and diverse ecosystem that stretches from the mountains to the sea, ki uta ki tai.
Ecological and biodiversity values: A wide variety of birds, fish, reptiles, invertebrates, plants, lichens, mosses and fungi, many of which are now threatened or endangered, have adapted to thrive in these challenging and dynamic environments, each of them dependent on one another.
Protecting and restoring braided river ecosystems
Over time, the ecological and biodiversity values of our region's braided rivers have deteriorated due to weeds and pest animals, water abstraction, land development, river control works and encroachment, climate change and damage from recreational use.
These once-thriving biodiversity hotspots need our help to protect their endangered ecosystems from extinction.
We address these issues in one of four ways:
Protecting and enhancing high-value biodiversity - focusing on upper catchments, regional priorities and investment in determining what works.
Community engagement and awareness – supporting community-led projects and groups such as BRaid and river care groups.
Managing areas and infrastructure – delivering projects that bring biodiversity benefits (for example, the berm transition project).
Combining approaches – using a mix of the above where they overlap.
Project highlights
Here are a few highlights of the projects undertaken in 2024/25. They focus on protecting and restoring braided river ecosystems, controlling invasive weeds and pest species, and enhancing habitats for threatened native birds.
Upper Waimakariri River weed control
This is an ongoing multi-party, multi-year coordinated and targeted weed control project across multiple land tenures over a diverse ecological landscape in the Waimakariri basin.
Partners: Department of Conservation (DOC), Land Information NZ (LINZ), University of Canterbury, Selwyn District Council, Kiwirail, NZ Transport Authority Waka Kotahi, landowners, and community groups.
Work done: The third year of ongoing weed control, guided by a weed control strategy, continues to reduce weed densities and protect braided river ecosystems and species. Operational work this year targeted sycamore, Russel lupin, holly, Spanish heath, and willow species at six locations.
Emergent sycamore invading shrubland beside Lake Pearson
Scattered Russel lupin invading braided riverbed in the Waimakariri at Turkey Flat
Waiau-toa/Clarence River mouth trapping
We started funding trapping at the Waiau-toa river mouth back in 2021, with Wildlife Management International Ltd running the traplines, to improve the breeding success of New Zealand’s only endemic gull the tarāpuka/black-billed gulls and other native shorebirds including tarāpunga/red-billed gulls and tara/white-fronted terns at the Waiau-toa River mouth.
Funding: The Kaikōura Water Zone Committee agreed to fund volunteer training to ensure the traplines continued to be maintained.
Work done: Wildlife Management International Ltd (WMIL) was contracted to deliver the training with local volunteers stepping up to take on the role of running the traplines. It is encouraging to see volunteers continuing to protect these taonga species from introduced predators like stoats, feral cats, and hedgehogs.
Tarāpuka/black-billed gull at the Waiau-toa river mouth. Photo credit: WMIL
WMIL staff training a volunteer. Photo credit: WMIL
Waiau-toa/Clarence River weed control
The Waiau-toa/Clarence River is the least modified river in Waitaha, and protecting its natural values and surrounding landscape is a high priority for us.
Work done: For more than a decade, we’ve co-managed a catchment-scale weed control programme on the Waiau-toa/Clarence River with LINZ, supported by DOC and district councils. Weed control took place from Lake Tennyson right through to the coast. Our contribution supported the LINZ biosecurity programme and contracted work in the St James, with a focus on gorse, broom, alder and Spanish heath.
Funding: This year, the programme received significant investment through biodiversity incentives and project funding. The Kaikōura Water Zone Committee also committed a further $10,000 from its action plan budget, supporting DOC’s willow control work on the Acheron River and funding a contract to control pampas grass on the lower Clarence River.
Pampas grass control, Waiau-toa/Clarence River
Spanish heath, Waiau-toa/Clarence River
Waiau-toa/Clarence River upper habitat management for tarapirohe/black-fronted terns
In partnership with Department of Conservation (DOC) and Land Information New Zealand (LINZ), and with support from Ngāti Kuri, we are working to protect and enhance braided river habitat in the upper Waiau-toa/Clarence River.
The focus is on improving breeding habitat for tarapirohe/black-fronted terns — one of Canterbury’s most threatened braided river birds. These birds are entirely dependent on braided rivers for nesting, with Canterbury estimated to contain around two-thirds of their national breeding habitat.
Work done: Over the past year, the project carried out outcome monitoring to compare breeding success in ‘treatment’ and ‘non-treatment’ areas. The work focused on created and enhanced braided river islands, which are generally safer breeding habitats than mainland sites. Monitoring assessed management actions such as deepening channels to deter predators, increasing island heights to reduce flood risk, trialling constructed chick shelters, and weed removal to provide open spaces for nesting habitat. These were compared against natural factors like flooding and drought.
Outcome: The outcome monitoring showed that island nesting sites consistently had higher hatching success than mainland sites.
Braided river island enhancement to improve breeding habitat
Large black-fronted tern chicks at one of the chick shelters
Southern black-back gull feeding on black-fronted tern chick
Charwell River predator trapping
Charwell River black-billed gull colony
The tarāpuka/black-billed gull is the world’s most threatened gull species found only in New Zealand. A colony of these rare birds is located on the Charwell River, a small braided river and tributary of the Conway River in North Canterbury.
Work done: Traplines were first established at the colony in 2022 to help improve breeding success. The Kaikōura Water Zone Committee committed to continue providing funding for the traplines for the 2024/25 season. Hemmings Contracting maintained the traplines, trapping 92 predators including 12 cats and 50 hedgehogs between November and June.
Outcomes: With the absence of nesting karoro/southern black-backed gulls, after successful control the previous season, the tarāpuka had a productive breeding season with the colony swelling to over 800 birds at its height.
Ashley River/Rakahuri braid island weed clearance
Mechanical ripping to clear braid island weeds on Ashey/Rakahuri river
The Ashley/Rakahuri is a vital habitat for several ‘threatened’ and ‘at risk’ native braided river and shore birds including tarapirohe/black-fronted tern, ngutu pare/wrybill and pohowera/banded dotterel. However, invasive weeds like lupins are encroaching on the riverbed, reducing the open gravel areas these birds need for nesting.
Support: The Ashley-Rakahuri Rivercare Group, a dedicated group of volunteers, work to protect this unique habitat. Every year, they remove lupins on braid islands to improve nesting habitats for these braided river birds.
Work done: With support from this project, the group was able to contract a tractor-mounted ripper to clear lupins ahead of the 2024/25 breeding season. Our biodiversity staff worked closely with the group onsite to oversee the work and ensure native plant species were protected during the clearing operation.
Upper Ohau catchment weed control
The Upper Ohau catchment is home to a unique mix of braided rivers, wetlands, springs, dry scrub, and tussock lands. Thanks to its relatively low number of invasive weeds, it’s one of the few places where weed control can still focus on eradication or containment.
Work done: Since 2018, the project has aimed to maintain the weed-free status of Department of Conservations (DOC) land in the Dobson and Hopkins River valleys. It also works to remove invasive species such as willows and lupins from the braided river bed and push other weeds further down the valley or into designated containment areas. Project partners include DOC, Land Information New Zealand (LINZ), and the catchment landowners.
Controlled weeds: The weeds being controlled in the catchment include crack willow, grey willow, alder, cotoneaster, elderberry, rowan, Russell lupin, and buddleia, along with a range of other species including raspberry, blackberry, flowering cherry, hops, gooseberry, and flowering currant.
Regional Pest Management: While species listed in the Canterbury Regional Pest Management Plan are not the main focus, they are controlled when found. Landowners and field staff remain vigilant and are always on the look-out for any new weed incursions so they can be controlled quickly.
Upper Ohau in 2019
Upper Ohau in 2022
Post-control crack willows
Hakataramea River weed control
In partnership with the Hakataramea Sustainability Collective (HSC) and landowners, we are working to control invasive barberry in the Hakataramea Valley.
Work done: Targeted control efforts have focused on outlying infestations from Meyrs Pass to Brothers Stream, following delimitation surveys to map the extent of spread. The goal is to prevent barberry from invading indigenous gray scrub communities and riparian margins — areas that include threatened species such as tree daisy (Olearia fimbriata) and scrambling broom (Carmichaelia kirkii).
Further up the valley, we continue to work with HSC, Department of Conservation (DOC), Land Information New Zealand and landowners to keep the upper Hakataramea braided river habitats and wetlands free from invasive broom, lupins, and willows. Contractor work funded by partner agencies is supported by volunteer hours coordinated by HSC to search for and control weeds in the side tributaries and clean main stem reaches.
Hakataramea River before and after weed control
Hakataramea Sustainability Collective, landowners and partners discuss control options in the field
Braided River Revival berm transition programme
This project continues to focus on strengthening flood defences by controlling exotic plant species that obstruct waterways and damage existing flood protection vegetation, and sub-canopy native planting. Sixty berm transition sites have been established in the past with works completed in December 2023.
Work done: Work over the past year focused on delivering maintenance across each of the sites. This follow-up weed control has resulted in a strong establishment of our restoration planting assets.
Monitoring efforts this year have focused on seedling recruitment, with encouraging results. Wild seedlings of native species such as kānuka, kōhuhu, kōwhai, and harakeke have been observed and recorded at multiple sites. These species were intentionally included in planting plans to complement and reinforce existing wild populations identified during the initial scoping phase.
Ongoing maintenance: Continued maintenance will help ensure these naturally regenerating plants are successfully incorporated into long-term reserves, strengthening both flood resilience and ecological health.
