In a 20-year nest box study of starlings (Sturnus vulgaris) in New Zealand, intraspecific fighting was the main mortality factor recorded. All fights were between birds of the same sex, 24 male-male and 22 female-female, and most were in the breeding season. Fighting increased as the population rose from about 300 birds in 1969 to over 3000 after 1978. Because of the low annual mortality rate of starlings in New Zealand (330/0), the chances of ever breeding were small for many birds. Hence conditions were ideal for a high level of fatal fighting, which took the form of grasping the opponent round the head so that the claws penetrated the brain through the eye sockets.
Observations of seabirds during two visits in the yacht Totorore to the southern extremity of South America in the summer and autumn of 1984 and 1985 are summarised with comments on their status in South America. Rockhopper and macaroni penguins (Eudyptes chrysocome and E. chrysolophus) are commoner than in the past, but larger penguins were not found breeding and may be more vulnerable since penguins still appear to be taken for bait. Chile holds about a sixth of the world’s breeding black-browed mollymawks (Diomedea melanophrys), a tenth of the grey-headed mollymawks (D. chrysostoma), many blue petrels (Halobaena caerulea) and narrow-billed prions (Pachyptila belcheri), and some southern giant petrels (Macronectes giganteus). The white-chinned petrel (Procellaria aequinoctialis) probably breeds, and possibly the fairy prion (Pachyptila turtur), collected in the past, and Antarctic cormorant (Leucocarbo bransfieldensis). The first Manx shearwaters (Puffinus puffinus) for Chile were also seen in the Magellan Strait and near Cape Horn.
This paper presents bird records from the Kingdom of Tonga which do not fit into other publications about the extensive field work of the Brehm Fund South Seas Expedition. Results of the first ornithological survey of the small island of ‘Eua’iki are presented. Most remarkably, this island has small numbers of Vini australis and Clytorhynchus vitiensis, which became extinct on ‘Eua and Tongatapu at the end of the 19th century. Other new distribution records for C. vitiensis are presented, and the record of its distribution in Tonga is revised. Its absence from the larger islands in southern Tonga is a result of human disturbance, most likely the introduction of Rattus rattus, while in the Vava’u group, competitive exclusion by Pachycephala jacquinoti may be the reason. Hirundo tahitica is now known from many locations. Breeding colonies seem to exist on Tofua and Nomuka, and a breeding population is probably establishing on ‘Eua. A few new data are added to the sparse knowledge about Pachycephala jacquinoti. Ardea novaehollandiae was recorded again from Tongatapu and Circus approximans for the first time from Tongatapu and Niuafo’ou. Records of Prosopeia tabuensis from Tongatapu and two of its offshore islands are given, and some remarkable changes in behaviour of Porphyrio porphyrio on small islands are reported. The brown female morph of Gallicolumba stairii, which has been known from Fiji and Samoa, is also in Tonga. An unidentified storm petrel has been seen close to Tongatapu. Breeding has been confirmed for Pterodroma nigripennis and Sterna sumatrana on several islands in the Tongatapu group. Some new breeding records for noddies (Anous spp.) on islands off Tongatapu are presented. Observations of Procelsterna cerulea on ‘Eua suggest that the species breeds in the cliffs of the east coast. Sterna anaetheta certainly breeds in cliffs on the southern coast of Tongatapu. The discovery of new breeding colonies of Pterodroma nigripennis supports the hypothesis that the species is extending its range. Blue-crowned lorikeets and Fiji shrikebills have been isolated on ‘Eua’iki for more than a century. These populations, and others, are very small (fewer than 100 birds each). Their size and long isolation call into question the concept of Minimum Viable Populations.
The islands of ‘Ata and Late have been visited for the first time by an ornithologist. The islands are important breeding sites for seabirds. Fregata ariel and F. minor nest on both islands. ‘Ata is the only Tongan island where Sula serrator dactylatra breeds. It also has a large population of Puffinus pacificus, and a few Procelsterna cerulea have been seen. Among forest birds, the abundance of Gallicolumba stairii on Late was most conspicuous. Among the rare and locally distributed birds of Tonga, the whistler Pachycephala melanops and the fruit-dove Ptilinopus perousii were found to be common. The lory Vini australis was seen only occasionally. On Niuafo’ou, jungle mynas Acridotheres fuscus have increased dramatically since 1984; the species is now considered a pest on fruit crops. The megapode Megapodius pritchardii seems to be threatened not only by the collecting of eggs, but also by development plans of the Tongan government. Numbers are probably higher than estimated in 1984. The avifaunal history of the three islands is discussed in the light of recent palaeontological findings. Human activities probably had a significant influence on the present-day composition of fauna and flora. The avifauna of Late probably comes close to that of a young volcanic island in pre-human times and so offers great chances for comparative studies in avian ecology. Finally, conservation issues are discussed, stressing the importance of remote Tongan islands for a regional concept of bird preservation.
Radio-tagging of 54 New Zealand pigeons (Hemiphaga novaeseelandiae) captured at Pelorus Bridge Scenic Reserve, Marlborough, showed that about half of the birds which fed there in spring on deciduous foliage moved away from the reserve from early summer onwards. They travelled 2-18 km to other areas of native forest. Most remained away for 2-9 months and at least some bred at their summer destinations. Individual birds tracked in different years provided strong evidence for their using traditional seasonal ranges, although the timing of movements varied between years, depending on fruiting phenology and breeding success. Some birds made up to three return movements from and back to Pelorus Bridge within a year, visiting different destinations in different seasons. Late summer and autumn movements were apparently linked to feeding on miro (Prumnopitys ferruginea) fruit. Five of 25 radio-tagged pigeons which moved to known destinations away from the reserve occupied areas of privately owned native forest during the breeding season.
The breeding and feeding of Kerguelen terns (Sterna virgata) and Antarctic terns (S. vittata) were studied at the Kerguelen Islands in January-February 1985. The laying period was estimated to have ended during the third week of December for Kerguelen terns and started during the last week of December for Antarctic terns. Kerguelen terns used a wide variety of feeding techniques and fed in marine, freshwater and terrestrial habitats. Marine crustaceans, fish and terrestrial invertebrates were the main prey. Antarctic terns fed only in marine habitats, where crustaceans were the main prey. Even when feeding close together, the terns were seldom aggressive. Contrary to previous reports, Kerguelen terns fed fish to chicks and fledglings despite the presence of Antarctic terns. Frequent strong winds prevail at the subantarctic islands, and so wind speed is probably the most important factor affecting the ecology of Kerguelen and Antarctic terns.