BREEDING SUCCESS AND PREDATION AT NESTS OF BANDED DOTTEREL (CHARADRIUS BICINCTUS) ON BRAIDED RIVERBEDS IN THE CENTRAL SOUTH ISLAND, NEW ZEALAND

New Zealand Journal of Ecology (1998) 22(1): 33-41 ©New Zealand Ecological Society (M. erminea L.), cats (Felis catus L.), hedgehogs (Erinaceus europaeus Barret-Hamilton) and Norway rats (Rattus norvegicus Berkenhout), and by native predators such as Australasian harriers (Circus approximans Peale) and black-backed gulls (Larus dominicanus Lichtenstein) (Pierce, 1987). However, the relative importance of these predators is not known. Previous studies in the Mackenzie Basin, especially work by Pierce (1986, 1987) in the Cass and upper Tekapo Rivers, showed that nest site location and timing of breeding influenced the breeding success of braided river birds. Pierce (1987) also suggested that sudden declines in rabbit (Oryctolagus cuniculus L.) abundance following 1080 (sodium monofluoroacetate) poisoning may be a precursor to high rates of predation at riverbed bird nests. The unstable river channels and high levels of disturbance present in braided rivers is a key factor regulating vegetation and the use of the areas by breeding birds. The original vegetation on braided rivers is highly specialised and consists primarily of ground cover plants, such as common scabweed (Raoulia hookeri) and an absence of tall vegetation (Parkinson and Cox, 1990). Reduced frequency of flooding because of the construction of hydroelectric power impoundments has led to the Introduction