The dispersal and survivorship of pateke (Anas chlorotis) in relation to experimental release techniques ; supplementary feeding and wing-clipping : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, Auckland

Abstract

The pateke, or brown teal (Anas chlorotis), is a cryptic species and this is reflected in the dearth of knowledge regarding their basic ecology and demography. The difficulty in establishing secure self-sustaining breeding populations at historic locations by introducing captive-bred birds is likely a reflection of a lack of knowledge about some aspects of their ecology, and therefore the necessary knowledge for their management. Two major factors appear to inhibit pateke reintroductions, these are dispersal out of predator controlled release areas and the associated mortality before viable breeding populations establish. This study aims to reduce these factors by increasing understanding of the causes, and refining release techniques. Secondary releases of captive-bred pateke to Tawharanui Regional Park and Cape Kidnappers and Ocean Beach Wildlife Preserve (CKOBWP) provided the opportunity to investigate whether populations could establish in the target areas under prescribed management regimes involving supplementary feeding and wing-clipping. Pateke at each site were fitted with radio transmitters to monitor dispersal, and PIT tags to monitor feeder use over 24hrs remotely. Supplementary feeding appeared to increase the time pateke spent at the release site, and in particular decrease the dispersal of male pateke postrelease. Supplementary feeding may also influence survivorship by reducing cases of starvation in newly-reintroduced pateke. Wing-clipping reduced dispersal and there were no apparent negative effects in terms of increased mortality or dependence on supplementary feed. It is hypothesised that wing-clipped birds may even increase residency of fully-flighted birds at release sites by acting as conspecific attractants. In addition to providing baseline data on these populations, the trialing of PIT tag technology on pateke in this study is likely to be significant because it provides an accurate low-labour method of data collection and thus has potential to improve both future studies of the species and the conservation management of pateke.