WADERS (CHARADRII) AND OTHER SHOREBIRDS AT CAPE RECIFE,ALGOA BAY,SOUTH AFRICA: SEASONALITY,TRENDS, CONSERVATION,AND RELIABILITY OF SURVEYS

Spearpoint, J. A., Every, B. & Underhill, L. G. 1988. Waders (Charadrii) and other shorebirds at Cape Recife, Algoa Bay, South Africa: seasonality, trends, conservation, and reliability of surveys. Ostrich 59: 166–177.

A total of 126 surveys of waders (Charadrii) and other shorebirds were made along 4 km of shore northwest of Cape Recife. The surveys were conducted bv two observers who counted independently of each other. The variability between observers was least for conspicuous species such as Whitefronted Plover, Blacksmith Plover, African Black Oystercatcher, Whimbrel and Grey Plover, but greatest for cryptic species such as Ringed Plover and for species which formed a minority in mixed flocks such as Curlew Sandpiper and Little Stint. Variability of surveys within years and between years is also considered. Turnstones and Sanderlings were the most abundant waders in summer. Of the Palaearctic waders, Turnstones, Grey Plovers, Sanderlings, Greenshanks and Whimbrels overwintered. In contrast, Ringed Plovers, Curlew Sandpipers, and Little Stints rarely overwintered. Little Egrets, Threebanded Plovers and Water Dikkops occurred mainly in winter. It is recommended that surveys to estimate numbers of Palaearctic waders in summer and winter should be conducted in December, January or February and June or July, respectively. Because of three-year cycles in breeding productivity of certain waders, surveys should be extended over at least three years. There was evidence that waders associated with rocky shores increased in numbers during the study period: this coincided with the erosion of sandy beaches near Cape Recife. Density, biomass and daily field metabolic rates, expressed on an area basis, were similar to those in eastern Scotland. Nine species of tern utilized Cape Recife. It is recommended that the bait-collecting regulations be enforced, that vehicles be prohibited on the beach, and that the tern roost and breeding site be fenced off to create a sanctuary.     

PREY OF NORTHERN ROCKHOPPER PENGUINS AT GOUGH ISLAND,SOUTH ATLANTIC OCEAN

Klages, N. T., Brooke, M. de L. & Watkins, B. P. 1988. Prey of Northern Rockhopper Penguins at Gough Island, south Atlantic Ocean. Ostrich 59:162-165.

The diet of Northern Rockhopper Penguins Eudyptes chrysocome moseleyi breeding on Gough Island, south Atlantic Ocean was studied, during November 1984, 1985 and 1986 by stomach content analysis. Rockhopper Penguins fed chiefly on the euphausiids Thysanoessa gregaria, Euphausia lucens and E. similis. Fish and squid were of minor importance by mass but constituted the largest individual prey items.     

COLONY AND HABITAT SELECTION OF SIX KELP GULL LARUS DOMINICANUS COLONIES IN SOUTH AFRICA

Kelp Gulls nested in six colonies on rocky islands, sand and rock cliffs, sand dunes and on a sand, gravel island in a salt lake. The colony sites selected were different from the surrounding areas and were generally inaccessible to ground predators. Kelp Gulls nested in a wide variety of habitats. Within colonies, the gulls did not nest randomly with respect to habitats but preferred to nest on flat, stable areas with some cover (either rocks or vegetation). They generally avoided heavily vegetated areas, areas devoid of vegetation and areas with steep slopes. Their specific habitat choices relate to predation and cannibalism pressures. Intermediate cover provides adequate protection for chicks while allowing for increased visibility and open escape routes for parents. Nearest neighbour distances were similar among colonies and habitats, indicating strong social attraction.     

COMPOSITION,ABUNDANCE AND SEASONALITY OF LARVAL FISH IN RICHARDS BAY HARBOUR,KWAZULU-NATAL,SOUTH AFRICA

Summary

The present study examined the composition, abundance and seasonality of fish larvae occurring in Richards Bay Harbour, over an 18-month period from June 1991 to November 1992. Ichthyoplankton samples were collected every six weeks at top, mid and bottom depths in the dredged channel 100 to 200 m from the harbour entrance. A total of 7 163 fish larvae, representing 105 taxa and 53 families, was collected throughout the study period. The dominant families were the Engraulidae and Gobiidae representing 50% and 37% of the total catch, respectively. The most abundant larvae were those of the thorny anchovy, Stolephorus holodon, and an unidentified goby, Gobiid 12 (32% and 30% of the total catch, respectively). Estuarine-associated taxa dominated the total catch in terms of density (61%), with 11 out of the 28 taxa being totally dependent on estuaries at some stage in their life cycle. Turbidity and temperature were significant variables accounting for 27% of the variation in larval densities of estuarine-dependent species. The main peak in larval density occurred in January 1992 (summer) with a mean larval density of 160 larvae per 100 m³. Larvae of estuarine-associated taxa were predominantly at the flexion and postflexion developmental stages. Since larval densities of certain estuarine-associated species were significantly greater in bottom samples and on flood tides, it is suggested that selective tidal stream transport is a recruitment mechanism used by these species. The present study concluded that it is important to maintain and preserve the estuarine component of Richards Bay Harbour so that the system can function as an estuarine nursery for many of the fish species depending on it at certain stages in their life cycle.     

GROWTH AND DISTRIBUTION OF A SOUTHERN ELEPHANT SEAL COLONY

In contrast with most southern elephant seal, Mirounga leonina , colonies, births at Península Valdes, Argentina, increased from 7,455 in 1982 to 9,636 in 1990. Colony size during the 1990 breeding season, including pups, was estimated at 19,000. Colony growth may respond to abundant food resources and lack of competitors. The range of distribution of elephant seals in Patagonia has not changed since at least 1972 but the spatial distribution of births along the coastline of Peninsula Valdes has varied. In 1982, 58% of the births occurred in the northeast portion of the Peninsula versus 36% in 1990. Females may prefer to give birth on broad, sandy beaches. In 1982, 56% of the females gave birth on pebble beaches and 44% on sandy beaches. In 1990, 24% bred on pebbles versus 76% on sand. Sand substrate may be preferred by females because it may confer thermoregulatory advantages in relieving heat stress.     

SEASONAL ABUNDANCE,HABITAT SELECTION AND ENERGY CONSUMPTION OF WATERBIRDS AT THE BERG RIVER ESTUARY,SOUTH AFRICA

Velasquez, C.R., Kalejta, B. & Hockey, P.A.R. 1991. Seasonal abundance, habitat selection and energy consumption of waterbirds at the Berg River estuary, South Africa. Ostrich 62:109-123.

The distribution and abundance of waterbirds at the Berg River estuary were studied between September 1987 and April 1989. The estuary supports an unusually high density of waterbirds, especially of Pale-arctic migrant waders, and is a site of subregional importance for at least nine species. Intertidal mudflats are the favoured feeding habitat of the majority of species on the estuary during the low tide period. Low tide feeding densities on saltmarshes are mud less than on mudflats, but saltmarshes are important as roost sites, high tide feeding sites, and in counteracting the negative hydrological consequences of development. The current conservation status of the estuary is not commensurate with its importance as a waterbird habitat and, given the current threats facing the estuary, enhanced protection at the national level is considered a greater priority than registration with, for example, the RAMSAR Convention.     

AN HOLISTIC APPROACH TO THE MANAGEMENT OF WATER QUALITY IN FALSE BAY,CAPE TOWN,SOUTH AFRICA

Summary

An overview of the water quality status of False Bay identified the bacterial/viral water quality of stormwater and rivers discharging near contact recreation beaches to be the management concern of highest priority. A second water quality concern is the potential impact of nutrients being discharged into False Bay on the surf zone and bay ecosystems. Heavy metals, hydrocarbons and industrial chemical discharges into the Bay are not regarded as a serious water quality threat. Much of the future development planned for Metropolitan Cape Town will impact on the volume and water quality of rivers, groundwater, stormwater and wastewater flowing into False Bay; hence the need for an integrated catchment management approach to the management of the bay.

An assessment of the constraints facing the holistic management of the bay and catchment concludes that the four main concerns are: (1) a lack of key research information on the options for stormwater management, and on the loading and potential impacts of nutrients being discharged into the surf zone and bay ecosystems; (2) jurisdictional fragmentation, and the lack of coordinated policy and planning between different local and government authorities and other users; (3) legislative fragmentation; and (4) a lack of private sector and public consultation by authorities. Preliminary ideas on the structure of a management body for False Bay and its catchment which address the concerns listed above are presented.     

BODY MEASUREMENTS,PLUMAGE AND MOULT OF THE SACRED IBIS IN SOUTH AFRICA

Lowe, K. W., Clark, A. & Clark, R. A. 1985. Body measurements, plumage and moult of the Sacred Ibis in South Africa. Ostrich 56: 111–116.

Body measurements, plumage and moult of Sacred Ibis Threskiomas aethiopicus were studied at Pretoria from July 1973 to June 1974. Adult and immature Sacred Ibises are sexually dimorphic in size. Bill length alone can be used to sex most birds. Body mass, wing, tarsus and tail lengths overlap greatly between the sexes but males are generally larger than females. The sexes show similar patterns of variation in body mass and gonad size throughout the year. Juveniles follow a different pattern of variation in these parameters. The plumages of adults, immatures and juveniles are described and compared. There is no sexual dimorphism in plumage pattersn. Moult in adults occurs mainly in the post-breeding period from January to August, and in juveniles and immatures throughout the year. Adult Sacred Ibises have an-extensive, irregular and asymmetrical moult. Factors affecting sexual size dimorphism in African and Australian populations are discussed.     

2. A WONDERFUL NESTING COLONY OF SACRED IBIS,HERONS AND OTHERS WADERS AT JOHANNESBURG

Skead, D. M. 1974. Roadside counts of Blackshouldered Kites in the central Transvaal. Ostrich 45: 5–8.

From August 1967 to November 1970 roadside counts of Blackshouldered Kites Elanus caeruleus were made along the Great North Road from the Pienaar's River Irrigation Settlement, near Hammanskraal, to Warmbaths, Transvaal. The mean density for this period was 10 km per bird. Counts were also made along the same route, but for a shorter distance to the farm Vaalbosch. The mean density for this route was 17 km per bird. Relative density was higher than in the Cape Province.     

WATER TEMPERATURE AND THE 1987 FISH KILL AT LAKE ST LUCIA ON THE SOUTH EASTERN COAST OF AFRICA

Summary

An unusually cold spell during the winter of 1987 caused a drop in water temperature at Lake St Lucia. This coupled with typical estuarine salinities in the lake resulted in a fish kill. The kill was one of the largest recorded in a South African estuarine environment and involved an estimated 250,000 fish comprising at least 21 species. Most fish that died belonged to small species. Densities of dead fish recorded along the lake's shoreline ranged from 0.1 to 16.6 fish per metre. It is concluded that the combination of low water temperature and near marine salinities was the major cause of the 1987 fish kill at Lake St Lucia.     

DISTRIBUTION,POPULATION SIZE AND CONSERVATION OF THE CASPIAN TERN STERNA CASPIA IN SOUTHERN AFRICA

Cooper, J., Brooke, R.K., Cyrus, D.P., Martin, A.P., Taylor, R.H. & Williams, A.J. 1992. Distribution, population size and conservation of the Caspian Tern Sterna caspia in southern Africa. Ostrich 63: 58–67.

The Caspian Tern Sterna caspia occurs along the whole southern African coastline and on large river systems and water bodies away from the coast. A total of 28 definite breeding localities has been recorded in southern Africa. Breeding has occurred recently at at least 14 coastal localities between Swakopmund, Namibia, and Lake St Lucia, Natal, South Africa. Inland breeding has been recorded in recent years at Sua Pan, Botswana and Kalkfonteindam, Orange Free State, South Africa. Based on censuses conducted between 1980 and 1991, the southern African breeding population is estimated to be of the order of 500 pairs, 91% of which breed coastally and 89% breed on islands. Up to 290 pairs (58%) bred at Lake St Lucia. Seventyone per cent of the 1980–1991 breeding population falls within eight nature reserves. Conservation of the Caspian Tern in southern Africa requires protection at breeding localities, including commercial salt and soda ash extraction works, against the effects of changing water levels, human disturbance and predation. Pesticide levels of addled and abandoned eggs should be measured at selected breeding localities.     

NITROGEN TRANFORMATIONS AND THE NITROGEN BUDGET OF A HYPERTROPHIC IMPOUNDMENT (HARTBEESPOORT DAM,SOUTH AFRICA)

SUMMARY

The major components of the nitrogen balance of hypertrophic Hartbeespoort Dam were studied at weekly intervals from October 1980 to September 1984. The Crocodile River contributed over 80Z of the hydraulic load and over 97X of the annual total nitrogen load to the impoundment. More than 802 of this nitrogen load was composed of nitrate. Monthly measurements of nitrification and denitrification rates carried out within the impoundment over one annual cycle revealed that the rates of both processes were highest at the ammonia-oxygen chemocline during summer stratification and at the sediment-water interface during winter isothermy. Mass balance calculations showed that between 35 and 49% of the annual total nitrogen load were lost via denitrification each year; the data are compared with those in the literature. Conditions in the lake will favour a change in phytoplankton species composition from Microcystis to a nitrogen-fixing species if the present trend of decreasing inorganic nitrogen concentrations and N: P ratios is maintained.     

TURRILITIDAE (CRETACEOUS AMMONOIDEA) FROM SOUTH AFRICA, WITH A DISCUSSION OF THE EVOLUTION AND LIMITS OF THE FAMILY

The helically coiled mid-Cretaceous family Turrilitidae Meek,1876 are abundant in late Albian and Cenomanian sediments ofEastern South Africa, including representatives of the generaPseudhelicoceras, Turrilites, Hypoturrilites, Ostlingocerasand Mariella, together with a new genus, Neostlingoceras (typespecies Turrilites carcitanensis Matheron, 1842).a Hypoturriliteshomoeomorph derived from Ostlingoceras. Twenty-two species andsubspecies are described, four of them new: Hypoturrilites crickisp. nov., Mariella (Mariella) acanthotuberculata sp. nov., Mariella(Mariella) oehlerti (Pervinquière) sulcata subsp. nov.and Mariella (Mariella) gallienii evoluta subsp. nov. The systematicpart.of the paper providesa basis for the discussion of thephylogeny, and some of the evolutionary trends shown by thefamily. An annotated synopsis of all genera and species referred tothe family is also included (Received 10 March 1977;     

POPULATION SIZE,DISTRIBUTION AND DISPERSAL OF KELP GULLS IN THE SOUTHWESTERN CAPE,SOUTH AFRICA

Steele, W.K. & Hockey, P.A.R. 1990. Population size, distribution and dispersal of Kelp Gulls in the southwestern Cape, South Africa. Ostrich 61:97-106.

There are indications that the Kelp Gull Larus dominicanus population of the southwestern Cape Province, South Africa, is increasing. It is proposed that decreased post-fledging mortality due to supplementary food from man's activities, at sites such as fishing harbours and refuse dumps, is likely to be the main cause of this population increase. Kelp Gulls aggregate, and juveniles (first-year birds) are disproportionately abundant, at sites where supplementary food is available. Juvenile dispersal from the two largest breeding colonies, 38 km apart, is in opposite directions.     

ASPECTS OF THE BREEDING BIOLOGY AND BEHAVIOUR OF THE SECRETARYBIRD SAGITTARIUS SERPENTARIUS NEAR PRETORIA,SOUTH AFRICA

Kemp, A. C. 1995. Aspects of the breeding biology and behaviour of the Secretarybird Sagittarius serpentarius near Pretoria, South Africa. Ostrich 66: 61–68.

Secretarybirds in three adjacent territories were monitored from 1977 to 1988 on grass- and croplands near Pretoria, South Africa. Most observations of breeding biology and behaviour confirmed or extended previous studies. There was no correlation between pairs in occupancy of territory, productivity or development periods of young: this confirms the flexible breeding abilities which are unusual for such a large bird. Some aspects of breeding biology (egg shape and texture, watering of chicks) and behaviour (Wings open and Up-down greeting displays) may be homologous with storks and important in understanding the phylogeny and evolution of the Sagitariidae and other diurnal raptors.