The ‘icon’ bird of the Ashley-Rakahuri River is the wrybill or ngutupare (Anarhynchus frontalis).
It is the only bird in the world with a side-ways turning bill, and apart from a few pairs in inland Otago, only breeds on the braided riverbeds of Canterbury. The Ashley-Rakahuri is one of its northern-most breeding sites, following a southward contraction of the core range of the species over the past century. Indications are that numbers of this species have been relatively stable on the river during the last few decades, with up to 10 pairs breeding in recent years.
The next two most important native species which breed on the Ashley-Rakahuri River are the black-fronted tern or tarapiroe (Sterna albostriata) and the black-billed gull or tarapunga (Larus bulleri). Over the last 20-30 years, numbers have declined substantially (particularly of gulls), mainly due to weed invasions, predation by introduced animals and human disturbance.
These three key species have been the main focus of management activities of the Group; all are listed as threatened with declining national populations. The most threatened is the black-billed gull (same status as the rarest kiwi species), followed by the black-fronted tern and the wrybill.
Other threatened native species nesting on the Ashley-Rakahuri are the banded dotterel or tuturiwhatu (Charadrius bicinctus), the pied stilt or poaka (Himantopus himantopus) and the pied oystercatcher or torea (Haematopus ostralegus). A single black stilt or kaki (Himantopus novaezelandiae) bred on the river up to 2009 (mated with a pied stilt). This species is a regualr visitor to the estuary over winter.
The riverbed breeding season starts in August-September and ends in January-February. Maps showing the breeding location of the wrybill, black-fronted tern and black-billed gull are available.
Populations of nearly all species have either remained stable or increased over recent years. The Table below shows survey results since 2000. For more graphic detail of both population trends and breeding outcomes, see Results Ppt 2014, plus a paper by Eric Spurr and Nick Ledgard published in the NZ Ornithological Society's journal Notornis (63/2, 2016) - 'Population trends of braided river birds on the Ashley River (Rakahuri), Canterbury, New Zealand. 1963 - 2015'.
Bird Surveys (one day in November, except 2002 (Oct)) and Breeding (all season) in the main riverbed study area (c. 18 km): 2000 – 2016
There was an improvement of bird numbers up to 2014, since when there are indications of decline. This appears to be associated with an increase in weed invasion of formerly open shingle areas – refer to Weed PowerPoint.
All photos by ARRG members - Lynley Cook, John Dowding and Nick Ledgard