Experiments were undertaken to identify the animals responsible for attacks on nests of Greenfinches (Carduelis chloris) on a mixed farm in Hawke’s Bay. Nests encased in wiremesh, which excluded all potential predators except mice, suffered no egg losses. Tracking papers placed on wooden poles leading to nests were marked by rats twice. Two ship rats (Rattus rattus) were killed at nests with eggs injected with strychnine.
Mustelids destroyed one clutch of eggs and were probably responsible for most of the predations on young. The experiments did not test whether Harriers (Circus approximans) or other birds were involved.
Breeding by 11 pairs of fantails (Rhipidura fuliginosa) was studied on Tiritiri Island during the 1981/82 breeding season. All pairs observed attempted to breed in late September or early October, but only three pairs laid eggs before November. Eight pairs each produced only one successful clutch. No new nests were begun after early December. I conclude that fantails may have a shorter breeding season and lower overall breeding success on islands than on mainland New Zealand.
The 1980/81 distribution of the Australasian Gannet (Sula serrator) in New Zealand is described and population changes since 1946 are examined. A brief history of the 26 breeding colonies and 23 roosts is given. Over 99% of gannets nested in the 23 colonies round the northern half of the North Island in 1980/81. Gannet roosts are mostly near the breeding colonies. The results of three national censuses taken since 1946 give an indication of the changes of the New Zealand gannet population in 34 years. The 1946/47 population was assessed at 21,115 pairs; 37,774 pairs were counted in 1969170 and
46,004 in 1980/81. The mean annual rate of increase for the whole population between 1946/47 and 1980/81 was 2.3%. In comparison with gannets in Australia, South Africa, and the North Atlantic, the gannet in New Zealand seems to be the only one steadily increasing and free from human interference.