Nesting home range sizes of Wrybill (Anarhynchus frontalis) and Banded Dotterel (Charadrius bicinctus) in relation to braided riverbed characteristics

Abstract

Wrybill (Anarhynchus frontalis) and Banded Dotterel (Charadrius bicinctus) are territorial birds which breed on braided riverbeds in Canterbury, New Zealand. Home ranges of Wrybill pairs were bigger than those of Banded Dotterel pairs on the Rakaia and Ashley Rivers. For Wrybill there were no significant differences in home range size between years and rivers, but home ranges of Banded Dotterel pairs were larger on the Rakaia R. than on the Ashley R. Wrybill home range size on the Rakaia R. was related to the presence of preferred minor channel feeding habitats; small home ranges contained mostly minor channels and large home ranges contained mostly major channels. The larger home ranges for Banded Dotterel on the Rakaia R. is thought to be related to greater habitat instability compared to the Ashley R. If large scale diversion of water occurs from these rivers then flows need to be managed so that the characteristics of the natural flow regime are maintained.