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Populations of the macaroni penguin Eudyptes chrysolophus and the eastern rockhopper penguin E. filholi breeding at Marion Island (Prince Edward Islands) in the sub-Antarctic Indian Ocean decreased from 1994 to 2018. We examined their diets when rearing chicks during this period. There was substantial overlap in the diets of the two species, with crustaceans, dominated by the euphausiids Thysanoessa vicina and Euphausia vallentini, making up >80% of the diets by number and >60% by mass over the study period. The lanternfishes Krefftichthys anderssoni and Protomyctophum tenisoni were the most-commonly consumed fish in the diet of breeding macaroni penguins and dominated in their diet in three of the 25 years (1994, 1998 and 2014); they were also the most commonly consumed fish by eastern rockhopper penguins. Macaroni penguins consumed more of the amphipod crustacean Themisto gaudichaudii and the lanternfish Electrona carlsbergi as well as a greater diversity of and larger-sized fish than did eastern rockhopper penguins. The horsefish Zanclorhynchus spinifer was found in substantial amounts in the diet of eastern rockhopper penguins in 1996 and 1997. Despite annual variations in relative prey contributions to the diets, there were no significant long-term changes in the diet of either penguin species over the study period or when compared with an earlier assessment in 1982. We conclude that changes in the relative proportions of prey in the diets of these penguin species during breeding are unlikely to account for the recent declines in these penguin populations.

This paper reports on growth of the Boulders colony of African penguins Spheniscus demersus from inception in 1985 to the present. More than 900 pairs now breed there. Growth of the colony slowed in 1995 and 1996and reversed in 1998, coinciding with periods of low abundance of Cape anchovy Engraulis capensis off South Africa. In December 1996, penguins were excluded from a portion of land where they had formerly bred. Theyresponded by increasing the density of their nests in other areas and expanding their area of breeding longshore. These patterns indicate that food and not space are currently controlling colony growth rate. Much of the colonygrowth probably results from immigration of first-time breeders from other colonies. Of immigrants, 70–80% may be from Dyer Island to the south-east, where numbers of penguins have decreased. Boulders also is frequentlyvisited by penguins from other colonies, and by rehabilitated birds.

In South Africa, kelp gulls Larus dominicanus first breed when 4 years old. At least 50% of 4-year-olds breed; virtually all older birds breed annually. Most chicks leave natal colonies in the austral autumn and winter, when about 6 months old, and 60% of them may not return until aged 2 or 3 years. One 3-year-old showed signs of defending territory, but birds only attain full adult plumage when aged 4. The plumage of 3-year-olds is similar to that of adults, but the white spots on the outer primaries are less well developed and the secondaries and inner primaries have no white trailing edge. Chicks are dark, whereas birds aged 1 and 2 years gain increasing amounts of pale or white plumage on the face, neck, underparts and tail.

The number of African penguins Spheniscus demersus breeding in South Africa collapsed from about 56 000 pairs in 2001 to some 21 000 pairs in 2009, a loss of 35 000 pairs (>60%) in eight years. This reduced the global population to 26 000 pairs, when including Namibian breeders, and led to classification of the species as Endangered. In South Africa, penguins breed in two regions, the Western Cape and Algoa Bay (Eastern Cape), their breeding localities in these regions being separated by c. 600 km. Their main food is anchovy Engraulis encrasicolus and sardine Sardinops sagax, which are also the target of purse-seine fisheries. In Algoa Bay, numbers of African penguins halved from 21 000 pairs in 2001 to 10 000 pairs in 2003. In the Western Cape, numbers decreased from a mean of 35 000 pairs in 2001–2005 to 11 000 pairs in 2009. At Dassen Island, the annual survival rate of adult penguins decreased from 0.70 in 2002/2003 to 0.46 in 2006/2007; at Robben Island it decreased from 0.77 to 0.55 in the same period. In both the Western and Eastern Cape provinces, long-term trends in numbers of penguins breeding were significantly related to the combined biomass of anchovy and sardine off South Africa. However, recent decreases in the Western Cape were greater than expected given a continuing high abundance of anchovy. In this province, there was a south-east displacement of prey around 2000, which led to a mismatch in the distributions of prey and the western breeding localities of penguins.Keywords: African penguin, diet, numbers breeding, numbers moulting, Spheniscus, survivalAfrican Journal of Marine Science 2011, 33(1): 139–156

Counts of African penguins Spheniscus demersus in immature and adult plumage in the feather-shedding phase of moult were made at Robben Island at two-weekly intervals over a 10-year period between 1988 and1998. For both age-classes, most birds moulted between November and January, although small numbers moulted throughout the year. In most years, the peak moult was in late November or December. Immature birdshad a secondary peak in March. In 1994/95 for adults, and 1995/96 for immature birds, moult was less synchronized than in other years. This probably resulted from oiling of about 2 400 penguins in June 1994, following the sinking of the Apollo Sea. Half of those birds were cleaned and released. Their subsequent moult may have been earlier than normal.

The abundant guano-producing seabirds in Peru and southern Africa feed mainly on the large populations of anchovy Engraulis spp. and sardine Sardinops sagax supported by the Humboldt and Benguela upwellingsystems. Numbers of guanay cormorants Phalacrocorax bougainvillii in Peru and the breeding population of Cape cormorants P. capensis in South Africa are significantly related to the biomass of anchovy. For both species,reproductive success decreases in periods of anchovy scarcity, and there may also be substantial adult mortality. There has been long-term stability in numbers of Peruvian boobies Sula variegata, whereas the numbers ofCape gannets Morus capensis decreased as sardine decreased in southern Africa. Numbers of Peruvian pelicans Pelecanus (occidentalis) thagus are significantly related to the combined biomass of anchovy and sardine inPeru. They have been stable in the long-term. There have been ongoing severe decreases in populations of the Humboldt penguin Spheniscus humboldti and the African penguin S. demersus, both of which are nowVulnerable. Common causes for the decreases have been collection of eggs, loss of habitat through exploitation of accumulated deposits of guano and competition with fisheries for food. Short-term decreases in guanay cormorants, Peruvian boobies, Peruvian pelicans and Humboldt penguins have followed El Niño events. Time-series of indices of the abundance of guano-producing seabirds date from 1908 in Peru and 1896 in southern Africa. They are significantly, negatively correlated in the period prior to the development of intensive fisheries on sardineand anchovy, suggesting that the out-of-phase nature of the anchovy and sardine populations in the Peru and Benguela systems pre-dated commercial exploitation of these fish resources.

Regional trends in numbers of African penguins Spheniscus demersus conform with an altered distribution of sardine Sardinops sagax and anchovy Engraulis capensis prey. In the 1950s, sardine dominated the pelagic fish component of the Benguela system. Abundance of this fish decreased in the 1960s and early 1970s and it was replaced by anchovy. Beginning in the early 1980s, sardine started to increase and anchovy to decrease in abundance. The decrease of the sardine resulted in collapses of colonies of African penguins between Lüderitz and Table Bay. Although colonies east of Table Bay increased, the overall population of African penguins fell by 25%. As the Benguela system started to revert to one dominated by sardine, penguin colonies between Lüderitz and Table Bay stabilized. Three new colonies were established in the vicinity of Table Bay, but the large colony at Dyer Island underwent a massive decrease. As a result, overall numbers of African penguins decreased by a further 19%. During shifts between regimes dominated by sardine and anchovy, African penguins that are breeding for the first time immigrate to colonies where food is plentiful. Inability of African penguins to cope with recent shifts between regimes may have resulted from increased competition for food with fishermen and seals during the 20th century.

South Africa is a global hotspot for oil pollution. The regional oiled seabird cleaning centre, the South African Foundation for the Conservation of Coastal Birds (SANCCOB), has handled over 50 000 seabirds from its inception in 1968 until 2005. The majority of seabirds oiled in South Africa are African penguins Spheniscus demersus, followed by Cape gannets Morus capensis, both of which are classified as Vulnerable to extinction. On the basis of the proportion of the population that has been affected, the African penguin is considered to have suffered more from oiling than any other seabird species globally. The rehabilitation success (proportion of birds known to have survived for at least one month in the wild) and restoration success (proportion of rehabilitated birds attempting to breed) of de-oiling penguins and gannets are higher than has been reported for any other species. The financial costs of de-oiling African penguins are substantially lower than the costs of de-oiling seabirds in the Northern Hemisphere. De-oiling contaminated birds is thus a valuable conservation intervention for these species, both of which are relatively localised in areas within or close to major shipping routes and ports, where a single spill can threaten a large proportion of the global population. There are, however, long-term effects of oiling on penguins and gannets. De-oiled gannets survive slightly less well than un-oiled birds, but the difference is similar to inter-colony differences in survival. Approximately 27% of rehabilitated African penguins are unable to breed following their release. In addition, oiling has a long-term negative impact on the breeding productivity and cost of reproduction in de-oiled birds. The primary objective should therefore be to prevent or reduce oil spills in the first place. However, future oil spills are inevitable and the authorities need to ensure that they have plans in place and the required capacity to respond rapidly to spills when they do occur. One of the ways to reduce the number of penguins becoming oiled during a spill is to evacuate birds from the affected area. The continued capture and cleaning of penguins and gannets that do become oiled is justified on conservation grounds. Thus, de-oiling should be a twin objective to prevention in South Africa’s oil spill management strategy, and every effort should be made to further improve both of these aspects. Keywords: African penguin; Cape gannet; Dassen Island; de-oiled; Morus capensis; oil spills; rehabilitation; rescue; restoration; SANCCOB; Spheniscus demersusAfrican Journal of Marine Science 2009, 31(1): 31–54

Dassen and Robben islands are approximately 50 km apart, and currently support the largest and third largest populations of African penguins Spheniscus demersus respectively. At both islands, moult is the most synchronised and seasonal activity of the annual cycle. The main difference in moult phenology between the two islands is the degree of synchronisation. The peak moult period at Dassen Island is broader (less synchronous) than at Robben Island. At both islands, juvenile penguins moulted less synchronously than adults. Juvenile moult was less synchronous at Dassen Island than at Robben Island. Interannual variation in moult phenology was similar at Robben and Dassen islands. Islandlevel moult phenology was more synchronous in the year following the Treasure spill than was the case after the Apollo Sea spill. This was attributed to the larger number and proportion of birds that were affected by the Treasure spill. The temporal duration of the disruption to moult phenology was also greater following the Treasure spill, especially at Robben Island. Moult counts provide a relatively reliable method of estimating the size of the adult population at Robben Island, but not at Dassen Island where the large number of birds moulting away from the shoreline results in the population size being significantly underestimated. Although the number of active nest sites continued to increase up until 2004 at both islands, the numbers of adult moulters counted declined by 55% between 2003 and 2005 at Robben Island, and by 50% between 2002 and 2005 at Dassen Island. The decrease in the number of moulters coincided with a decreased availability of food in the region. Keywords: African penguin, Dassen Island, moult phenology, population trend, Robben Island, Spheniscus demersusAfrican Journal of Marine Science 2009, 31(1): 19–29

There have been recent changes in the distributions of several seabirds in South Africa. In the mid-1990s, breeding of Leach's storm petrel Oceanodroma leucorhoa was recorded in the Western Cape, the first record for the Southern Hemisphere. There was a large eastward expansion in the breeding range of crowned cormorant Phalacrocorax coronatus sometime between the early 1990s and the early 2000s, and in that of Hartlaub's gull Larus hartlaubii between 1995 and 2000. A smaller eastward expansion in the breeding range of kelp gull Larus dominicanus was noted in 2006. In 2003, a new colony of African penguins Spheniscus demersus formed in the east of the Western Cape, but after 2004 there were large decreases of penguins at colonies in the west of this province. South Africa's northern most penguin colony became extinct in 2006. In the early 2000s, there was a decrease in numbers of Cape gannets Morus capensis breeding in the Western Cape, but a large increase in the Eastern Cape. Numbers of Cape P. capensis and bank P. neglectus cormorants decreased in the north of the Western Cape in the 1990s, but increased at some southern localities in the 2000s. A similar pattern was noted for kelp gulls, except that the decreases in the north took place in the 2000s. The proportion of swift terns Sterna bergii in the Western Cape that bred in the south of this province increased markedly in the mid-2000s. Although local factors may have played a role in the distributional changes, their consistent anticlockwise nature, the broad similarity in their timing and their widespread occurrence suggest the influence of environmental change, perhaps forced by climate. This hypothesis is supported by similar displacements of other South African marine resources and congruent changes in seabird populations in the South-West Indian Ocean. Keywords: climate change; colonisation; distributional shift; range expansion; seabird; South AfricaAfrican Journal of Marine Science 2008, 30(1): 189–193

Off South Africa, anchovy Engraulis encrasicolus and sardine Sardinops sagax are the main prey of African penguins Spheniscus demersus. The combined spawner biomass of these fish increased from less than one million t in 1996 to more than nine million t in 2001 and then decreased to four million t in 2005. The combined biomass of young-of-the-year of these species increased from 0.2 million t in 1996 to 3.2 million t in 2001 before falling to 0.4 million t in 2005. There was a large eastward shift in the distribution of sardine between 1999 and 2005. The number of African penguins breeding in the Western Cape Province increased from 18 000 pairs in 1996 to more than 30 000 pairs from 2001 to 2005 before falling to 21 000 pairs in 2006, as the availability of fish decreased near breeding localities. Numbers of penguins breeding and numbers of birds in adult plumage moulting were significantly correlated with the young-of-the-year biomass of anchovy and sardine and with the available biomass of spawning sardine. The increase in the number of penguins breeding was mainly attributable to a greater proportion of birds breeding and improved breeding success. The decrease probably resulted from high mortality. Delayed first breeding and abstinence from breeding during periods of food shortage may both increase survivorship when food is scarce and enable seabirds rapidly to take advantage of improved feeding conditions. Although long-lived seabirds are buffered against short-term variability in food supplies, environmental change that influences the abundance and availability of prey can have severe consequences for central-place foragers, such as penguins, if there is long-term displacement of prey to regions where no suitable breeding localities occur.Keywords: African penguin; breeding proportion; breeding success; food; mortality; Spheniscus demersusAfrican Journal of Marine Science 2008, 30(1): 167–175

In South Africa's Western Cape Province, numbers of bank cormorants Phalacrocorax neglectus breeding at 11 localities decreased from above 500 pairs during 1978–1987 to 350 pairs from 1995 to 2006. The most northern colony (Lambert's Bay) was extinct by 1999 and there were substantial decreases at the two largest colonies (Malgas and Dassen Islands), also north of Cape Town. There was long-term stability at three smaller colonies near Saldanha and fluctuating growth at Robben Island near Cape Town, where the colony was twice affected by oil spills. Between Cape Point and Cape Hangklip, two colonies were monitored and their numbers increased. Farther east, numbers at the Dyer Island group showed a slight decrease. These trends are consistent with a reduced abundance of West Coast rock lobsters Jasus lalandii in the north and an expansion of this resource to the east, but not yet as far as Dyer Island. Rock lobsters were the most important item in the diet of bank cormorants to the north of Cape Town.Keywords: bank cormorant; food; Jasus lalandii; Phalacrocorax neglectus; oil spill; population trend; rock lobster; South AfricaAfrican Journal of Marine Science 2008, 30(1): 161–166

For rockhopper penguins Eudyptes chrysocome at Marion Island, there were significant decreases over time in the numbers breeding and breeding success at three monitored colonies from 1985/1986 to 2006/2007, and in mass on arrival for breeding of both males and females from 1994/1995 to 2007/2008. Breeding success decreased by 0.15 chicks pair–1 y–1 over 22 years and was significantly correlated with mass on arrival of males and females. Survival of chicks at the guard stage was low in the late 1990s; hatching success decreased in the early 2000s. It is thought that an increasingly poor parental condition caused birds to abandon breeding at a progressively early stage. Parental condition is influenced by feeding opportunities at overwintering grounds, which have probably been altered by global climate. Keywords: breeding success; climate change; Eudyptes chrysocome; parental condition; rockhopper penguin; sub-AntarcticAfrican Journal of Marine Science 2008, 30(1): 185–188

In the 2002/2003 breeding season at Malgas Island, South Africa, 125 nests of Cape Gannets Morus capensis, of which at least one partner was of known age, were monitored. The age of birds at these nests ranged from five to 22 years. At five nests, the ages of both partners were known; ages were similar for birds younger than 10 years but dissimilar for older birds, suggesting Cape Gannets initially choose partners of a similar age but may replace lost partners with younger birds. First clutches, all consisting of one egg, were mainly laid in late September (estimated laying dates 15 August to 1 November). Of first clutches, 61% failed. Relaying took place at 11% of failed nests. Overall, pairs successfully fledged chicks at 43% of nests; no pair fledged two chicks. Breeding success was positively related to the distance of the nest from the edge of the colony, but tended to decrease as age increased. Height of nest and date of laying did not influence breeding success. Older birds bred earlier and further from the edge of the colony than did younger birds. Ostrich 2008, 79(1): 67–72

From 2001 to 2006, two new designs of flipper bands made from silicone rubbers were tested on African penguins Spheniscus demersus at 365 nests on Robben Island, South Africa. We compared, over six years, the breeding success, from hatching to fledging, of three different groups of penguins: those with rubber bands (117 nests), with conventional stainless-steel bands (103 nests) and without bands (145 nests). There were no significant differences in breeding success between the three groups, suggesting that neither the currently used steel bands, nor either of the new rubber-band designs, were harmful during the seasons investigated. The rubber bands caused less wear of feathers and less drag on a model penguin than the steel bands. In captivity, the behaviours of African penguins fitted with rubber bands were not noticeably different to those of unbanded birds.Keywords: African penguin; behaviour; effects of flipper-banding; drag; fledging success; silicone rubber; Spheniscus demersus; stainless steelAfrican Journal of Marine Science 2008, 30(3): 595–602

Cape fur seals Arctocephalus pusillus pusillus were estimated to kill some 6 000 Cape gannet Morus capensis fledglings around Malgas Island in the 2000/01 breeding season, 11 000 in 2003/04 and 10 000 in 2005/06. This amounted to about 29%, 83% and 57% of the overall production of fledglings at the island in these breeding seasons respectively. Preliminary modelling suggests this predation is not sustainable. There was a 25% reduction in the size of the colony, the second largest of only six extant Cape gannet colonies, between 2001/02 and 2005/06. There has been a large increase in predation by Cape fur seals on seabirds around southern African islands since the mid-1980s, coincidental with both an increase in the seal population, altered management of the islands and an altered distribution of prey for gannets and seals. At Malgas Island, most gannet fledglings were killed between 10:00 and 18:00, the period when most are in the water around the island, from mid-January to mid-March, the main fledging period. The Cape gannet is classified as Vulnerable. Keywords: Arctocephalus pusillus pusillus, Cape fur seal, Cape gannet, fledgling mortality, Malgas Island, Morus capensis, predationAfrican Journal of Marine Science 2006, 28(3&4): 681–687

Latham Island, Tanzania, was surveyed in August 2004 — the first known survey of the island outside the period October–March — and in December 2005. On both surveys, four species of seabird were breeding at the island. Larger numbers of swift tern Sterna bergii thalassina and common noddy Anous stolidus plumbeigularis were breeding in August than in December, but the converse was true for masked booby Sula dactylatra melanops and sooty tern Sterna fuscata nubilosa. The estimated breeding populations of the four species were: masked booby (3 700 pairs), swift tern (320 pairs), sooty tern (4 400 pairs) and common noddy (4 000 pairs). These represent about 20%, 50%

At Latham Island, Tanzania, in August 2004 and December 2005, flying fish (Exocoetidae) contributed 90% by mass of prey items regurgitated by masked boobies Sula dactylatra. The fish had a mean caudal length of 164mm. Two boobies generally foraged in deep water, away from the Tanzanian coastline, ranging up to 390km from the island. Maximum distances flown on trips exceeded 1 000km during breeding and approached 3 000km when not breeding. Some foraging trips exceeded six days. Swift terns Sterna bergii consumed small fish and mantis shrimps Natosquilla investigatoris. Mantis shrimps recovered from the colony were significantly larger than those stranded on the island's beach, suggesting that swift terns preferentially took larger animals. Sooty terns Sterna fuscata fed on small fish and squid.Keywords: food, foraging, Latham Island, masked booby, sooty tern, Sterna bergii, Sterna fuscata, Sula dactylatra, swift ternAfrican Journal of Marine Science 2006, 28(1): 109–114