Often, it is only the bird’s movement that will alert you. On the broad reaches of braided riverbeds, wrybills, with their grey backs and white bellies, are superbly cryptic. Among the swathes of gravel and ground-hugging plants, nests may be impossible to see. Unless the incubating bird moves. The eggs and chicks are similarly cryptic – precisely adapted to that environment. Youngsters scarper and stumble over the stony flats, freezing into invisibility if a parent alarms. Then there is that peculiar bill.
There occurs in the avian kingdom a great diversity of bills – shape, size, length, colour, structure. There are the improbable spoonbills, the bizarre toucans or the far eastern curlew, where the bill seems to go on forever. But only wrybills – ngutu pare, unique and found only in Aotearoa New Zealand –have that bill curved sideways. Like a Swiss Army knife, it is a multi-purpose instrument. Birds probe beneath submerged river stones for caddis-fly or may-fly larvae. Good food out of reach of more conventional bills.
After breeding on South Island rivers, wrybills migrate north – most of the population heading for the Manukau Harbour and Firth of Thames. There, on the soft tidal flats, another feature of the bill emerges. On the vertical axis inside the curve, the upper and lower mandibles slope inwards. With its head held to the side, the bird now has a bill resembling a shallow spoon. The distinctive flick of its head identifies a foraging wrybill from a great distance as it sifts through the biofilm layer on the mud surface, seeking micro-organisms such as diatoms. Yet the wrybill can also tug a worm from the mud, like any other bird on the flats.
Then there are the aerial ballets of a wrybill flock over a high-tide roost. Frenetic twists and turns followed by languid loops as 2000 birds tease apart then coalesce, flashing white underparts changing to dark as they turn away. A string of birds peeling off and spiralling down like unravelled wool hung across the sky, before twisting and spooling upwards.
Yet these charismatic creatures are largely unknown to many New Zealanders. If people do know of them, they may not know of the vital connection with the braided rivers that flow from the Southern Alps, such as the Waimakariri, Rakaia and Rakitata – the only places wrybill can breed.
They are rivers under stress, with reduced natural flows through water abstraction and other land-use practices that enable weed encroachment, which in turn stabilises gravel bars and beaches, thereby inhibiting the dynamic movement of channels and islands.
The invasive vegetation also provides habitat and cover for mammalian predators that wreak havoc on river birds. Disturbance from vehicles adds to the pressure. The ultimate outcome is modified riverbeds and degraded nesting habitat for wrybill and other species such as tarapirohe (black-fronted terns), kakī (black stilts) and pohowera (banded dotterels).
There is much good work being done to address these issues. Environment Canterbury, DoC, Project River Recovery and community groups such as Ashley-Rakahuri Rivercare, are making a difference. But much more needs to be done, and it needs to be resourced and sustained if we are to secure a future for wrybill.
We also need to look after our tidal flats. Every three years, the Hauraki Gulf Forum’s State of Our Gulf report catalogues continuing deterioration of water quality in the Firth of Thames, largely attributed to land-use practices in the catchment.
Utterly dependent on two quite different habitats at each end of the country, these birds need to be firmly placed on Kiwis’ radar screen. Which is why we are campaigning to vote wrybill Bird of the Year. Voting runs from September 15-28. To support the wrybill, go to votewrybill.nz
Keith Woodley is the manager of the Pūkorokoro Miranda Shorebird Centre in the Firth of Thames.
