Food Preferences of Takahe in Fiordland National Park, New Zealand, and the Effect of Competition from Introduced Red Deer

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Abstract
The summer diet of takahe (Notornis mantelli), an endangered gallinule, in the alpine grasslands was investigated over 2 yr by counting takahe droppings and feeding sign in permanent plots of each of the 4 main tussock species and by recording the feeding sign along line transects through their territories. A similar assessment of preferences was made for introduced red deer (Cervus elaphus). Both takahe and deer prefer certain snow tussock species (Chionochloa pallens and C. flavescens) over others (C. crassiuscula and C. teretifolia). Between Nov.-Dec. takahe prefer C. flavescens to C. pallens but thereafter until April C. pallens is preferred. The order of general consumption of leaf bases of the 4 tussock species by takahe (C. pallens > C. flavescens > C. crassiuscula > C. teretifolia) corresponds to the relative amounts of major nutrients and sugars they contain. Another important food item is the leaf base of Celmisia petriei which is particularly rich in Ca and sugars. Selection occurred between plants of Chionochloa flavescens and C. pallens for the highest levels of P in spring and early summer, and of C. flavescens plants for phosphorus in autumn. Deer also show preference for snow tussocks with the highest nutrient levels. Competition between deer and takahe for quality food may explain the elimination of takahe from areas west of the Murchison Mountains where the greatest modification to the grasslands has occurred. The poor condition of the beech forest understory in the eastern Murchison Mountains, by affecting the over-wintering of takahe has probably also contributed to the decline in this area. Rhizomes of the summer-green fern Hypolepis millefolium are an important winter food source for takahe in the forest.

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