Funding boost for weed control in Waiau Toa Clarence river

Kaikōura’s Waiau Toa Clarence Weed Control Project recently received a $250,000 funding boost from Land Information New Zealand (LINZ) to help protect the character and function of the alpine braided river and its native flora and fauna.

Birds like the Nationally Critical black-billed gull and the Nationally Endangered black-fronted tern will benefit from the targeted weed control, along with the Nationally Critical slender button daisy among many other threatened dryland plant communities.

Nationally critical, endangered and threatened ratings are given to New Zealand species in order to determine the conservation status of them. This status guides threat management, protection, and monitoring work. 

Biodiversity funding bolsters weed control efforts

Endangered Black-fronted Tern chick

Endangered black-fronted tern chick (credit Jack Van Hal, DOC)

In 2016, the Waiau Toa Clarence Weed Control project was recommended by Kaikōura Water Zone Committee for $250,000 of biodiversity funding.

Spread over five years, the project aims to protect indigenous biodiversity in Waiau Toa Clarence with ongoing weed and pest control in the catchment.

A weed control strategy, also recommended by the committee, was developed in 2019 to direct efforts and set priorities for eradication, containment, surveillance, and advocacy for weed control in the catchment.

This ongoing advocacy from the committee has helped to build strong foundations for the partnerships within this project.

Awareness-raising attracts funding

As awareness of the project and interest in the catchment’s dryland ecosystems and recent plant species discoveries increased, so too has support from other individuals and agencies.

Group of people standing in a circle

Project partners coming together for predator control at Waiau Toa Clarence

Local landowners, station managers, LINZ, the Department of Conservation (DOC), Wildlife Management International, the water zone committee and Environment Canterbury are all working together to protect braided river bird habitat and rare plant species in Waiau Toa Clarence.

LINZ has supported the project with $30,000 each year since 2016 and this year increased their commitment to $250,000 for the control of weeds in 2020/21. They are also increasing their involvement in managing the project.

Boffa Miskell biosecurity consultant, Sian Reynolds, said "the Clarence River catchment is an ecologically significant ecosystem, and we are delighted to help in its restoration.

"The collaborative nature of this work has enabled a comprehensive plan to be devised, meaning we will see real gains for this catchment in the coming years. It is very exciting!"

Weed control programme to protect braided river's character

Restoring the natural character of braided rivers as iconic natural landscapes is a priority for the community, as outlined in the collaborative Canterbury Water Management Strategy (CWMS).

In a 2018 Environment Canterbury report, weed invasion was identified as one of the greatest threats to the braided river ecosystem in Waiau Toa Clarence.

Broom was found to be the most problematic riverbed weed in the upper areas of Waiau Toa Clarence, alongside crack willow and gorse. Several other weed species such as tree lupin and Spanish heath were identified as having the potential to become a problem in the catchment.

The report noted a management programme would be required to contain or eradicate the species from areas within the catchment.

As a result, the project has focused on long-term weed control to protect the braided river character and biodiversity values, with regard for more than 100 at risk and threatened flora and fauna in the wider Waiau Toa Clarence environment.

The protection and enhancement of mahinga kai values, indigenous biodiversity habitat and species, and ki uta ki tai (from the mountains to the sea) have all been drivers for success within the project.

Weed control work to date this year

February 2020
Targeted aerial control of broom and gorse was carried out, followed by additional aerial control of weeds in the riverbed adjacent to station owners who carried out independent weed control on their properties.
April 2020
Further aerial weed control took place after surveys of black-fronted tern nesting islands indicated weeds were growing back on the islands and predator numbers were increasing adjacent to weed infestations. Both these factors reduce the viability of nesting sites so needed to be addressed. 

This work supported the black-fronted tern predator control – upper Clarence project, which has been running a trapping program since 2015 to improve fledging success.
September 2020
Ground control methods have been used to clear tree lupin from black-billed gull nesting habitat at the hāpua/river mouth.

Project’s next steps

The first lot of work will be upper catchment weed control of gorse and broom (downstream of Lake Tennyson towards the St James Homestead).

Over the next six months additional actions will be undertaken including:

Slender button daisy

Slender button daisy, rediscovered from extinction

  • Raft accessed weed control in the lower catchment.
  • Spanish heath eradication and containment.
  • Gorse, broom, willow and buddleia weed control using a combination of vehicle and raft access, ground control and aerial control.
  • A biocontrol agent will be released to target buddleia where it forms a dense infestation.
  • Aerial weed control of broom and gorse around black-fronted tern nesting sites and below, to keep the riverbed and islands clear while reducing seed sources on the river terraces.
  • Follow-up control of broom around the site where slender button daisy (Leptinella filliformis) was rediscovered from extinction.

This work will be undertaken in collaboration with the project partners, alongside other strategic actions and planning, to ensure the best value for money within the project.

Find out more

Images credited to Heath Melville