Measuring body length of a tōrea (South Island pied oystercatcher)
With the ultimate goal of protecting and restoring the mobile manu and birdscapes of Aoteoroa, our researchers have recently teamed up with multiple partners in pilot programmes on tōrea (South Island pied oystercatchers), kākā and miromiro (tomtits; see Backpacking kākā and miromiro on the move). In all programmes, Strategic Science Investment funding is being used to grow our capability in this research area, while leveraging and engaging the resources and skills of operational and citizen partners and developing new knowledge together.
Technology tracking tōrea
Tōrea are one of our ‘internal migrant waders’ which breed in South Island braided river valleys in spring and enjoy life on the coast in winter. Their impressive mobility makes conservation management challenging because they encounter diverse threats throughout their annual migratory cycles, including while they are on the move and in coastal wintering grounds.
A multi-year research collaboration between Manaaki Whenua, the Department of Conservation (DOC) and the Ornithological Society of New Zealand (OSNZ) aims to reveal for the first time how the major predator-management programmes of Environment Canterbury, LINZ and DOC in riverbeds contribute to national population outcomes of iconic braided river species such as tōrea.
The programme relies on GPS technology to track tagged tōrea that head to winter feeding grounds from the upper Rangitata Valley. Anne Schlesselmann says a research team tagged 32 adult and fledgling tōrea with GPS transmitters in spring 2020. They also monitored the survival of more than 60 nests and fledglings on high country farmland and riverbeds in the upper Rangitata valley.
“We indexed predator densities with cameras to better understand what levels of predator control are necessary for successful tōrea breeding,” says Dr Schlesselmann. “Many additional adults and fledglings were banded in the Rangitata valley with small coloured ‘flags’ to identify them on wintering grounds.”
Complementary GPS-tagging and banding by DOC and OSNZ on wintering grounds started last June and is now rolling out across the country’s harbours. Early results show high adult and chick survival under predator trapping, as well as some remarkable spatial patterns since birds have taken flight. Already, tracks indicate some key national northward and southward flyways and the sheer extent of the North and South Island habitat network that supports wintering tōrea.
Manaaki Whenua aims to use the data to develop a spatial population model linking wintering and breeding sites of different tōrea subpopulations in different habitats and under different management regimes. DOC’s focus is building richer data on flyways and ‘nodes’ (key sites in time and space) by catching, tagging and banding birds on wintering grounds. OSNZ’s national citizen scientist network will boost both through re-sightings of banded birds.
Field research for this project has been mainly funded by MBIE’s Strategic Science Investment Fund, with Environment Canterbury co-funding enabling predator indexing and helping to support time-intensive fieldwork.