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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
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.