Exotic weeds are being controlled over 33,000 ha of riverbed, to maintain and restore native plant communities and wildlife feeding and breeding habitat. Russell lupin, broom, gorse, wilding conifers and crack willow are key weed species that Project River Recovery targets in braided rivers. Highest priority is given to preventing weed invasion of the near pristine ‘upper rivers’ above the Basin’s uppermost hydro lakes.
Project River Recovery runs an eradication programme for yellow tree lupin and buddleia in the upper Waitaki Basin. It also runs an ongoing surveillance programme to spot any new invasive weeds that could threaten braided rivers.
Project River Recovery also carries out research that aims to improve how weeds are managed in braided rivers. One recent trial tested the effectiveness of a new more environmentally-friendly herbicide for use on Russell lupins around waterways. A second trial examined the viability of Russell lupin seeds in relation to their stage of seed pod development when herbicide is applied, to determine whether our weed control operations can effectively be extended to later in the season. The results of both trials are currently being analysed.
Project River Recovery and the Kakī Recovery Group are working together to test a catchment-wide predator trapping regime in the Tasman River. This project involves a range of predator control and monitoring techniques.
The breeding success of several braided river birds – wrybill/ngutu pare, banded dotterel/pohowera and black-fronted tern/tarapirohe – is being monitored over five years to assess whether this level of predator control is helping these birds.
Project River Recovery is also working on developing an effective localised predator trapping regime to protect black-fronted tern/tarapirohe colonies. The regime is being trialled on a tern colony on an island in the upper Ohau River, and if successful there it will be tested on riverbed colonies.
Around 100 ha of new wetlands have been created. Water levels in these wetlands are controlled by weirs to maximise feeding habitat for braided river birds during the breeding season.
These wetlands also provide habitat for specialised wetland bird species like the Australasian bittern/matuku and the marsh crake/koitareke.
Project River Recovery’s research and management work is complemented by a public awareness campaign, aimed at increasing knowledge and respect for braided rivers and their unique wildlife.
This includes giving talks to school and university groups and working closely with Meridian Energy, Genesis Energy, Ngaï Tahu, regional and district councils, riverbank neighbours and others.