An analysis of the gizzard contents of 50 North Island brown kiwis, Apteryx australis mantelli, and notes on feeding observations

The kiwis analysed contained a wide range of invertebrate food species, most of which are associated with the bush margin. Individual gizzards contained high numbers of cicada nymphs and other species that are numerous, available throughout the year, or gregarious, and their presence is believed to reflect their availability rather than the bird's ability to select. Earthworm chaetae were present in 94%, and coleoptera (30% as adults. 70% as larvae) in 90% of 50 gizzards examined. A list of all invertebrates recorded in this, and earlier studies, is appended. Vegetable matter was found, often as incidental ingesta, in 93% of the samples and seed intake appeared to be inversely related to grit ingestion with hinau berries in particu- lar playing a part in grinding food. Observations of captive birds indicates a likely intake of 330 Kcal of food each night, and their willingness to catch aquatic prey suggests that under- water foraging provides the principal use for their nasal valves. Both captive and feral kiwis demonstrate a reliance on olfaction for locating foods.