Short note
No evidence that dietary nutrient deficiency is related
to poor reproductive success of translocated takahe
Ian G. Jamieson*
Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand
Received 15 November 2002; received in revised form 16 May 2003; accepted 17 May 2003
Abstract
The aim of the study was to identify from the existing literature the essential nutrients that are known to affect egg fertility and
hatching success in birds, and compare the concentrations of these between source and translocated populations of the endangered
New Zealand takahe. Takahe are herbivorous, and those that have been translocated to highly modified island sites with pasture
grasses have higher rates of egg infertility and low hatching success compared to takahe that breed in native tussock grasslands in
Fiordland. Nine essential nutrients were analysed from infertile eggs collected from Fiordland and four island sites over a 4-year
period. Only manganese showed any evidence of being in low concentrations in island takahe relative to Fiordland takahe, a result
consistent with earlier analysis that showed low concentrations of manganese in takahe plant-foods on islands. However, manga-
nese was in lowest concentrations on Kapiti Island where takahe consistently have the highest reproductive success of the four
island sites, with 10 of the 15 samples from the other three islands falling within the range of the Fiordland samples. Therefore
neither manganese nor any of the other eight essential nutrients appear to be widely deficient in island birds. Based on the results of
this study, a supplementary feeding programme to improve egg fertility in takahe is not recommended.
# 2003 Elsevier Ltd. All rights reserved.
Keywords: Avian diet; Egg infertility; Nutrients; Porphyrio; Translocation
1. Introduction
Obtaining proper energy and nutritional needs is
essential for survival and successful reproduction for
birds living in the wild (Murphy, 1996). Procurement of
food and energy requirements are not so much a prob-
lem for birds living in captivity, but nutrients essential
for breeding can sometimes be lacking in artificial diets,
thus prompting many zoos and conservation agencies
involved in captive breeding programmes to include
nutritionists on their staff. Conservation managers deal-
ing with free-ranging populations can take some comfort
in the fact that nutritional deficiencies of birds living in
the wild are rare (Robbins, 1983; Klasing, 1998). This
applies to birds living in their natural habitat, but what
happens when an endangered species is translocated
outside its historical range or to a refuge habitat that
might be slightly different or modified relative to that of
the source population? Whether the new environment
can provide the essential dietary nutrients to allow the
successful establishment of the new population is a
relevant question in assessing translocation pro-
grammes, but is rarely investigated directly. This is
partly because nutrient requirements and deficiency
levels, although well researched in domestic birds (e.g.,
National Research Council, 1994), are generally
unknown for free-living birds (Robbins, 1983; Klasing,
1998).
This study examines whether dietary nutrient defi-
ciencies are related to reduced reproductive success in
translocated populations of the highly endangered
takahe (Porphyrio hochstetteri). Takahe are a large (up
to 4 kg), flightless, herbivorous rail endemic to New
Zealand (Bunin and Jamieson, 1995; Lee and Jamieson,
2001). Although once widespread throughout New
Zealand, the only remaining natural population of
takahe occurs in the South Island in mountainous
Fiordland, where they feed primarily on highly nutri-
tious native grasses and ferns (Mills et al., 1980, 1991).
As part of a management strategy, Fiordland takahe
0006-3207/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0006-3207(03)00216-7
Biological Conservation 115 (2003) 165–170
www.elsevier.com/locate/biocon
* Fax: +64-3-479-7584.
E-mail address: ian.jamieson@stonebow.otago.ac.nz (I.G.
Jamieson).