THE SEA-BIRDS OF GOUGH ISLAND

Between November 1955 and May 1956 continuous observations were made on the sea-birds of Gough Island. These have been augmented by further occasional observations during seven subsequent years, and are compared with all previous published records for the island.
A check-list of 30 species of sea-birds has been compiled and substantiated, as far as possible, by a series of skins of 20 species.
Nearly 900 sea-birds cf 20 species were caught and measured, considerably more than at any previous time there; in the case of eight species, these are analysed in detail and some are compared with those from other populations.
The relative status of each species was estimated, together with total breeding populations where possible. In same cases the distribution of nests was mapped.
A detailed sound and photographic record, of 14 and 16 species respectively, was made.
Numbers of Wandering Albatrosses Diomedea exulans dabbenena and skuas Catharacta skua hamiltoni were ringed and colour-marked respectively to enable a more detailed study to be made of them.
General observations were made on the nesting seasons, breeding behaviour and moult of various species which are treated systematically.     

THE BAOBABS OF MADAGASCAR

Summary. The genus Adansonia (Bombacaceae) is reviewed, with particular reference to those species native to Madagascar. Their taxonomy, distribution, habitat, pollination, fruit-animal interactions, seed dispersal and economic importance are discussed.     

THE SEA-BIRDS OF THE SOUTHEAST COAST OF ARABIA

The present study of an upwelling area off the southeast coast of Arabia, between 52° and 60° E. is based primarily on observations on board the R.R.S, `Discovery’ during the International Indian Ocean Expedition. During oceanographic surveys off the Arabian coast from June to August 1963 and in early March and late May 1964 I made 234 counts of birds of about an hour each, the results of which have been used as an index of bird density. In this area, the only offshore islands known to be important to sea-birds are the Kuria Muria Islands, which were apparently at the centre of an upwelling area. The upwelling of cold water along the Arabian coast during the southwest monsoon from May to September greatly increases organic production in the sea, and large populations of organisms at every level of the food chain develop there. Previous work in Arabia and the Arabian Sea is reviewed. Little is recorded about the ecology of sea-birds there, but the composition of the fauna is quite well-known. The distribution of every sea-bird species recorded from 52° E. to 60° E., and within 200 miles offshore, is described, with particular reference to my own observations. Details are given of the distribution of common species during the southwest monsoon of mid-June-mid-August 1963 and in March and May 1964. Specimens collected on the `Discovery’ are recorded together with their measurements. Of 12 sea-bird species seen commonly off Arabia during the southwest monsoon in 1963, 11 were seen in late May 1964, but only five in March. There is certain evidence that two species have bred on the Kuria Muria Islands and suggestive evidence for a further three. Information on breeding seasons in the Arabian Sea is based on short visits to breeding colonies, mostly outside the breeding season, and on the plumage condition of specimens. Nevertheless, the sum of the evidence suggests that breeding is regular at the same time every year, and in most species seems to be in the northern summer. The food of sea-birds in the Arabian Sea, determined from stomach contents and visual observation, only serves to stress the lack of knowledge on this subject. A brief summary of feeding methods recorded by me suggests that they may be important in avoiding interspecific competition, for there seems to be little overlap. The density of sea-birds during the southwest monsoon 1963, expressed as the number of each species seen per hour, was analysed in relation to: (i) the sea surface temperature, which was inversely correlated with the zooplankton density from 0–200 m. (ii) the distance from the Kuria Muria Islands, the only likely breeding station; (iii) the distance from the nearest land which may have been important to land-tied sea-birds. All the abundant species were commonest close to land in the cool-water area and, with the exception of migrants from the southern hemisphere, most were concentrated around the Kuria Muria Islands in the centre of upwelling. A multiple analysis suggested that the islands were of real importance to some species. A separate analysis also demonstrated the existence of a correlation between sea-bird numbers and the abundance of zooplankton from 0–200 m. depth, but not the abundance of zooplankton at the sea surface. During the southwest monsoon the southeast Arabian coast is inhabited by a distinctive cool-water fauna within the tropical zone of the Indian Ocean. The high degree of endemism, the high proportion of migrants, including some from the southern hemisphere, and the absence of most pantropical species, suggest that the marked changes in the environment off southeast Arabia demand considerable adaptation. A brief discussion of the possible origins of the Arabian coast sea-bird fauna shows that it is not typical of either a subtropical or a tropical community in other regions. The likelihood that sea-birds breed in the summer, the concentration of most species in the upwelling area at that time and their absence during the winter, clearly demonstrates the importance of the upwelling. However, the results of the analysis suggest that some species were concentrated around the Kuria Muria Islands in the centre of the upwelling because the islands had a real importance to them, possibly as a breeding station. The correlation between sea-bird density and zooplankton abundance in the top 200 m., but not at the surface, may be explained if sea-birds concentrate in areas of high productivity rather than in areas of abundant surface plankton, which is largely irrelevant as food.     

SEA-BIRDS AT LAGOS AND IN THE GULF OF GUINEA

Regular observations of sea-birds were made in the vicinity of Lagos, southwest Nigeria, between October 1967 and June 1971. Records in the Gulf of Guinea were obtained in April 1969 and, together with others from Ghana and Sierra Leone, were used to complement this study. While few large populations of sea-birds are supported, the diversity of species occurring at Lagos and over offshore deep water was great. The occurrence of nine species of sea-bird new to Nigeria was established or confirmed; most of these were also new to West Africa southeast of Gambia. Details are given of fluctuations in numbers these and a further 16 species.
All coastal habitats at Lagos supported a large population of immature Black Terns, and groups of immatures made up a high proportion of observations of other Palaearctic terns and of Royal Terns, which breed only in northwest Africa. In contrast, the Lesser Black-backed Gulls and Damara Terns reaching Lagos (from breeding grounds almost two continents apart) were mainly adults; both these species are amongst those showing a current increase in numbers. A pronounced spring passage was observed among species including Royal and Sandwich Terns, but adult movements in autumn were not elucidated. The occurrence of the European race of the Little Tern in southwest Nigeria was confirmed, it is at least a regular spring migrant. The frequency of vagrants in January and February was linked to local climate as much to general distribution. Brief comment is also given on immature plumages, and the growing exploitation and pollution of coastal waters.     

THE PELAGIC DISTRIBUTION OF SEA-BIRDS IN THE WESTERN INDIAN OCEAN

The present paper summarises observations made during the International Indian Ocean Expedition on board the R.R.S.' Discovery, from August to November 1963 and from February to September 1964 in the Indian Ocean north of 20° S and west of 70° E. In 1963 work was carried out in the Somali Basin. In 1964 a series of transects were made over the ocean, the main purpose of which was to investigate the system of equatorial currents and the changes in the sea associated with the onset of the Southwest Monsoon in May. The Tropical Indian Ocean is briefly described. Except for local concentrations, the surface layers are poor in nutrient salts and plankton. There is a seasonal reversal of winds and surface currents in the Arabian Sea, but seasonal changes become less marked further south. Previous ornithological observations in the western Indian Ocean are mostly confined to the Arabian Sea or to the island groups. Thus, existing information on the pelagic range of pantropical species is incomplete. Observations made on each transect across the Indian Ocean in 1964 are summarised and compared with oceanographic data collected at the same time. General conclusions are not possible on the basis of so little information, though there appeared to be some relationship between the distribution of certain species and wind or current belts. The only marked discontinuity recorded was a concentration of Puffinus pacificus and Gygis alba at the northern edge of the Equatorial Counter-current at 58° E in March. Observations made on transects that were repeated before and after the onset of the Southwest Monsoon suggested that Sterna fuscata concentrates in the equatorial region as the monsoon develops. In general, both plankton and sea-birds were more abundant at 58° E than at 67¹/₄° E. An analysis of the presence or absence of sea-birds during each observation period, which lasted an average of one hour, established the difference between pelagic species and those largely restricted to within 50 miles of their breeding stations. There was no evidence of any correlation with zooplankton abundance, though birds of all species taken together were commonest where flying-fish were most abundant and S. fuscata appeared to be commonest in cool-water areas with strong winds, i.e. the Trade-wind belts. It was not possible to sample the food organisms of sea-birds quantitatively. Sea-bird observations in the Indian Ocean more than 200 miles from the continental coasts are summarized and compared with previous observations. The little information collected in the Indian Ocean agrees with previous work in the Pacific Ocean, where sea-birds are commonest in areas of convergence, and not where local upwelling and an associated concentration of plankton occur, such as on the equator. This may be due to the fact that populations of organisms on which sea-birds feed develop or concentrate a considerable time after upwelling of nutrient-rich water occurs. Since few sea-birds were seen feeding, it seems likely that available food is scarce and that much time is required to locate areas where it is abundant. Finally, evidence is presented to indicate how some sea-bird species may avoid or reduce competition by feeding at different distances offshore, or in different geographical areas.     

中国南海海岸的红树林

红树林是热带海岸潮滩上一种特殊的植被类型和生物资源。我国南海海岸为我国红树林的重要分布区,包括桂、粤、台、闽南部海岸,但主要是广东省的海岸,尤为海南岛。群落的组成种类丰富,有21科、27属和38种,其中红树林的有9种,占世界红树科种数的54％。我国红树林根据其群落的各种特征,可以划分人海滩红树林和海岸半红树林两类,共包括15个群落类型,其组成种类、外貌结构与马来半岛及其邻近岛屿相似。因此,我国的红树林应属于世界红树林的东方群系。 木文还介绍我国南海海岸红树林的分布和演替,并根据红树林的特点提出保护和经营管理问题。