Opportunity Nest Egg: introductory insights from kiwi O.N.E. data on chick nutritional responses and some aspects of life history
Lindsey Gray1 and Britt Mitchell2
1 School of Life and Environmental Sciences, University of Sydney, Camperdown, Sydney, NSW, Australia 2006 (lindsey.gray@sydney.edu.au)
2 Centre for Ecosystem Science, School of Biological, Earth and Environmental Science, UNSW, Sydney, NSW, Australia 2052 (brittany.mitchell@unsw.edu.au)
We present an analysis of data from 306 kiwi chicks that were hand-raised as part of Operation Nest Egg. Chicks were from Coromandel, Eastern and Western taxa brown kiwi raised at the National Kiwi Hatchery, Rotorua, and from rowi and Haast tokoeka at the West Coast Wildlife Centre, Franz Josef. From 2016–2018, a new maintenance diet was introduced at NKH and WCWC. The new diet was formulated to improve health, and replaced an “old” diet. We determined the nutritional composition of each diet and then, taking advantage of the congruence in husbandry methods used at both ONE centres, compared the growth responses of brooder room chicks from each taxon to the diets. We found that the new diet is much closer to the estimated wild adult kiwi diet in macronutrient composition, being high in energy and fat, while most of the energy in the old diet comes from protein. The new diet also provides a better Ca:P ratio, more omega fatty acids, and more carotenoids. While the new diet supports more consistent growth efficiency outcomes across the taxa than the old diet, we found a lot of variation in responses – especially between the Coromandel, rowi and Haast populations. These differences highlight the need to refine the chick captive diet, especially for chicks of differing genetic backgrounds and ages, and we present methods to achieve this. Improving chick diets is important as ONE continues indefinitely, and the life-long and trans-generational impacts of inappropriate developmental nutrition are becoming well known.
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