THE WINTER DIET OF GENTOO PENGUINS AT MARION ISLAND

La Cock, G. D., Hecht, T. & Klages, N. 1984. The winter diet of Gentoo Penguins at Marion Island. Ostrich 55: 188–191.

The diet of Gentoo Penguins Pygoscelis papua at Marion Island was studied during September 1982. Samples were obtained from 64 birds using a stomach-pump. Fish accounted for 70% of the diet by wet weight, and crustaceans 30%. Fishes occurred in 72% of the samples, crustaceans in 75%, cephalopods in 13%, and molluscs in 8%. Cephalopods and molluscs did not form a significant proportion of any single sample. Harpagifer georgianus was the predominant fish in the diet (92,7% of otoliths recovered), and Nauticaris marionis was the only crustacean.     

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 LAYING INTERVAL AND INCUBATION PERIOD OF ROCKHOPPER AND MACARONI PENGUINS

Williams, A. J. 1981. The laying interval and incubation period of Rockhopper and Macaroni Penguins. Ostrich 52: 226–229.

The laying interval and incubation period of Rockhopper Penguins Eudyptes chrysocome and Macaroni Penguins E. chrysolophus were studied at Marion Island in 1974–75 and 1976–77. On average, the laying interval was 4,4 and 4,5 days, the incubation period of second-laid eggs was 34,2 and 35,9 days and that of first-laid eggs was 39,1 and 38,0 days in Rock-hopper and Macaroni Penguins respectively. The laying interval in this genus is longer than that in other penguins. The incubation period is similar to that of most other penguins but the second-laid egg normally hatches before the first-laid egg. The long laying interval and the hatching sequence of the eggs both have important affects upon the mortality of eggs in the genus Eudyptes.     

PREY SELECTION AND TEMPORAL VARIATION IN THE DIET OF SUBANTARCTIC SKUAS AT INACCESSIBLE ISLAND,TRISTAN DA CUNHA

Ryan, P.G., & Moloney, C.L. 1991. Prey selection and temporal variation in the diet of Subantarctic Skuas at Inaccessible Island, Tristan da Cunha. Ostrich 62:52-58.

More than 2 500 prey items of Subantarctic Skuas Cuthuructa anturcricu were identified from regurgitated pellets collected at a roost of non-breeding skuas during summer 1989–90 at West Point, Inaccessible'Is-land. Most prey items (96,5%) were birds, primarily burrow-nesting procellariiforms. Sixteen bird species were recorfed in the diet, but five secies accounted for 94,6% of identifiable prey remains: Whitebellied Storm Petrel Fieettu grullariu (53,5%), Whitefaced Storm Petrel Pelugodrorna marina 15,1%), Broad-billed Prion Pacaptilu vittutu (14,0%), Great Shearwater Puffinus gruvis (7,3%), and Iommon Diving Petrel Pelecunoids urinutrix (4,7%). Petrel chicks were important in the diet, particularly Great Shearwaters. The main non-avian prey were fish and goose barnacles Lepas sp., but their importance may have been underestimated. The remains of a rat Rattus sp. presumably were derived from the neighbouring island of Tristan da Cunha; rats are not known to occur on Inaccessible Island. Prey size affected seabird availability to skuas, and dietary composition vaned throughout the summer in relation to seabird breeding cycles. Both these factors reduce the value of skua diet as an indicator of the relative abundances of burrow-nesting petrels. There was no correlation between skua diet and estimates of breeding bird abundance, but this may be a consequence of studying non-breeding skuas. Subantarctic Skua diet in 1989–90 was similar to that recorded in previous years, with consistent seasonal trends between years.     

ENTANGLEMENT IN MAN-MADE DEBRIS OF ANTARCTIC FUR SEALS AT BIRD ISLAND, SOUTH GEORGIA

Neck collars of man-made marine debris were seen on 208 Antarctic fur seals (and removed from 170) during the 142 days of the 1988–1989 pup-rearing season at Bird Island, South Georgia. This represents at least 0.1% of the total Bird Island population and a minimum of 0.4% of animals in the best covered areas; a maximum value might approach 1%. Polypropylene straps (packaging bands) formed 59% of collars, nylon string (16%), fishing net (13%) and six other materials comprised the rest. Males accounted for 71% of entanglements, 88% of which were of young (1–4 yr old) animals; females accounted for 64% of animals older than this. Obvious physical injury was being caused to 30% of animals and only on 19% of animals was the collar loose enough potentially to come off. The magnitude of the problem at South Georgia is similar to that with northern fur seals at the Pribilof Islands, where a significant population decline has occurred concurrently. Antarctic fur seals are still increasing in numbers but stricter controls on the jettisoning of debris into the Southern Ocean ate needed if the entanglement problem is not to increase beyond the level of a potential threat.     

ESTABLISHMENT,GROWTH AND CONSERVATION OF A MAINLAND COLONY OF JACKASS PENGUINS SPHENISCUS DEMERSUS AT STONY POINT,BETTY'S BAY,SOUTH AFRICA

Whittington, P.A., Hofmeyr, J.H. & Cooper, J. 1996. Establishment, growth and conservation of a mainland colony of Jackass Penguins Spheniscus demersus at Stony Point, Betty's Bay, South Africa. Ostrich 67: 144–150.

Following the discovery of a single pair of Jackass Penguins Spheniscus demersus nesting on the mainland at Stony Point, Western Cape Province, South Africa (34 22S 18 53E) in 1982, a colony developed and has since been regularly monitored. Numbers of nests increased to 35 in 1986, until a leopard Panthera pardus severely reduced the size of the colony. Numbers subsequently rose again to a total of 139 nests in 1990, but fell to 57 in 1993. This decrease was probably due to predation by mammals. Following the use of a trap and translocation of the animals caught, the colony increased again in 1995 and 1996. Productivity of the colony was insufficient for it to be self-sustaining, and it therefore presently represents a population sink.     

ESTIMATION OF PREY DENSITIES REQUIRED BY WESTERN NORTH ATLANTIC RIGHT WHALES

The apparent lack of significant recovery of western North Atlantic right whale populations may be related to the availability of prey in exploitable densities. We have attempted to estimate the concentration of zooplankton required by right whales to obtain a net energetic benefit over the long term, using estimated values for body weight, metabolic rate, assimilation efficiency, time spent feeding, mouth size and swimming speed. The estimated range of required energy densities is 7.57 to 2,394 kcal m⁻³ (3.17 × 10⁴ to 1.00 × 10⁷ joule m⁻³). These values are from one to more than three orders of magnitude greater than the densest concentration sampled in the vicinity of right whale aggregations in the Great South Channel. Right whales must seek out and exploit extremely dense patches of prey organisms in order to feed efficiently. The presence of such dense patches of zooplankton is likely to be a primary characteristic of spring, summer and fall right whale habitats.     

DIURNAL ACTIVITY OF ADELIE PENGUINS PYGOSCELIS ADELIAE AT CAPE BIRD

Activity cycles of non-breeding Adelie Penguins were investigated at Cape Bird, Antarctica. There was continuous light during the observation period, but none the less regular fluctuations of light intensity and temperature were maintained. The penguins had no single period of rest, but were active throughout the 24 hours. However, there were statistically significant diurnal variations in the levels of certain activities among non-breeders, with an overall reduction in activity-levels in the middle of the day, especially on warm midsummer afternoons. It is suggested that this cyclic activity minimum may be associated with the low heat tolerance of Adelie Penguins.