THE BREEDING-SEASON OF 3 SPECIES OF KIWI (APTERYX) IN CAPTIVITY AS DETERMINED FROM EGG-LAYING DATES

Records from kiwi (Apteryx spp.) breeding centres were used to obtain laying dates of 403 North Island brown kiwi (Apteryx ausiralis mantelli) eggs, 24 great spotted kiwi (Apteryx haastii) eggs and 25 little spotted kiwi (Apteryx owenii) eggs. North Island brown kiwi outdoors had an annual cycle of egg-laying with 88-5% of eggs laid from June to January. Eggs were laid in every month of the year, with fewest eggs in April (2.1% of all eggs). The greatest number of eggs was laid in July (15.6% of all eggs), with a second peak of laying in October (13.5% of all eggs). Both the great spotted kiwi and little spotted kiwi had annual cycles of egg-laying, with the main egg-laying seasons being August - January (87-5% of eggs) for the former and July - December (96.0% of eggs) for the latter. The highest peaks of laying were in October and August, respectively. Kiwi eggs were considered to belong to the same clutch if they were laid no more than 40 days apart. Clutch size in the North Island brown and little spotted kiwi was most commonly one or two eggs. In the great spotted kiwi only clutches of one egg were found. The mean clutch size of North Island brown kiwi outdoors (1.51 +/- 0.05) did not differ from that of free-living North Island brown kiwi (1.33 +/- 0.09). Similarly, there was no difference in the mean clutch size of captive and free-living little spotted kiwi (1.39 +/- 0.14 and 1.10 +/- 0.07). The mean interval between eggs for kiwi outdoors did not differ between North Island brown kiwi and little spotted kiwi (27.4 +/- 0.5 and 30.7 +/- 1.8 days). The results indicate that all three species of kiwi maintain annual cycles of egg-laying in captivity, with the main egg-laying season being longer than in free-living birds.