LIFE OF THE CROWNED HORNBILL. Lophoceros suehelicus australis. Territorialism,Family Life and Breeding

Duffy, D. C. 1987. Ecological implications of intercolony size-Variation in Jackass Penguins. Ostrich 58: 54–57.

The culmen length of courting adult male Jackass Penguins Spheniscus demersus varied between colonies, with the largest culmens in southern Namibia and east of Cape Point, South Africa. Taxonomic distance, a single measure combining several morphological characters, was significantly and positively correlated with geographic distance between colonies.

Population changes between 1956 and 1978 were not significantly correlated with male mandible or flipper length, suggesting that adult size cannot be used as an index of population changes at individual colonies. Possible dispersal may complicate attempts to use changes at individual colonies as indices of changes in fish stocks of surrounding waters.     

Lumbering the gauntlet: Cape Gannet fledglings killed by African Penguins

This account presents the first known observations of Cape Gannet Morus capensis fledgling mortalities as a result of aggressive nest defence behaviour by African Penguins Spheniscus demersus. Observations were conducted in 2013 on Bird Island, Algoa Bay, South Africa – the world's largest breeding colony of Cape Gannets. Twentyeight attacks were witnessed between 21 March and 18 May 2013 of which 16 resulted in mortality. The absence of previous observations of this phenomenon may be due to an unusually high proportion of African Penguin chicks being present relatively early on in the breeding season, associated with a potential for increased nest defence at this stage, and a larger number of gannet fledglings that year compared to previous years over the same period.     

Is food availability limiting African Penguins Spheniscus demersus at Boulders? A comparison of foraging effort at mainland and island colonies

The African Penguin Spheniscus demersus (Vulnerable) formed three new colonies during the 1980s, two on the South African mainland (Stony Point and Boulders) and one on Robben Island. One of the mainland colonies, at Boulders, Simon's Town, is in a suburban area, resulting in conflict with humans. Growth of the Boulders colony was initially rapid, largely through immigration, but has since slowed, possibly as a result of density‐dependent effects either on land (where there has been active management to limit the spread of the colony) or at sea. We test the latter hypothesis by comparing the foraging effort of Penguins feeding small chicks at island and mainland sites, and relate this to the foraging area available to birds. Three‐dimensional foraging paths of African Penguins were reconstructed using GPS and time–depth loggers. There were no intercolony differences in the rate at which birds dived during the day (33 dives/h), in diving depths (mean 17 m, max. 69 m) or in travelling speeds. The maximum speed recorded was 2.85 m/s, with birds travelling faster when commuting (average 1.18 m/s) than when foraging (0.93 m/s) or resting at sea (0.66 m/s during the day, 0.41 m/s at night). There were strong correlations between foraging trip duration, foraging range and total distance travelled. Foraging effort was correlated with chick age at Robben Island, but not at Boulders. Contrary to Ashmole's hypothesis, birds from Boulders (c. 1000 pairs) travelled further (46–53 km) and foraged for longer (13.2 h) than did birds from Robben Island (c. 7000 pairs) and Dassen Island (c. 21 000 pairs) (33 km, 10.3 h). The mean foraging range also differed significantly between mainland (18–20 km) and island colonies (9 km). The area available to central‐place‐foraging seabirds breeding on the mainland is typically less than that for seabirds breeding on islands, but the greater foraging range of Boulders birds results in an absolute foraging area roughly twice that of island colonies, and the area per pair is an order of magnitude greater for the relatively small Boulders colony. Ashmole's hypothesis assumes relatively uniform prey availability among colonies, but our results suggest this does not apply in this case. The greater foraging effort of Boulders birds probably reflects reduced prey availability in False Bay, and thus the recent slowing in growth at the colony may be the result of differential immigration rather than management actions to limit the spatial growth of the colony.     

Cave breeding by African Penguins near the northern extreme of their range: Sylvia Hill,Namibia

Only three mainland sites are known among the total 27 breeding colonies of the African Penguin, Spheniscus demersus: two in South Africa and one in Namibia. The latter is a unique cave site near the northern extreme of the species' range on the edge of the Namib Desert. To determine the colony size, long-term viability and any difference in breeding ecology relative to more southern sites we combined data from previous visits to the site with four visits in 2001. We found that about 240 to 300 birds use the Sylvia Hill cave, and about 90 nests are active with a laying peak in January. Eggs are laid on top of guano mounds not in burrows as is usual for this species. Smaller clutches (1.68 eggs/nest) but larger broods (x = 1.31 chicks/nest) were apparent in this colony than those farther south. Larger mean clutches farther south suggest a latitudinal trend in clutch size for Namibia's penguins. We found no evidence for a population decline over 17 years, and thus no evidence that birds at the periphery of their range moved southwards into core areas. We conclude that the colony is healthy and thriving despite a general decline in penguin numbers in southern Africa.     

ECTOPARASITE LOAD IN A LAUGHING DOVE WITH A DEFORMED MANDIBLE

At Dyer Island, South Africa, observations of predation of seabirds by Cape Fur Seals Arctocephalus pusillus pusillus were made during 2004 and 2006/07. It was estimated that seals killed about 7% of adult African Penguins Spheniscus demersus annually. This may have contributed to the penguin colony not increasing in spite of food becoming more available in its vicinity during an eastward shift of epipelagic fish resources off South Africa at the start of the twenty-first century. Adult penguins were most susceptible to mortality in the breeding season as they returned to feed chicks in the evening. Seals also killed substantial numbers (3–9%) of Cape Cormorant Phalacrocorax capensis fledglings as they left the island, mostly in the morning. The losses of Cape Cormorant fledglings accounted for about 95% of the overall mortality of seabirds attributable to seals. Mortality inflicted by seals on adults of four species of cormorant was negligible and no predation by seals on gulls and terns was observed.     

THE SYSTEMATIC POSITION OF THE SOUTH AFRICAN GANNET

Summary

Randall, R. M., Randall, B. M., Cooper, J. &; Frost, P. G. H. 1986: A new census method for penguins tested on Jackass Penguins Spheniscus demersus. Ostrich 57: 211–215

A census method for Jackass Penguins based on their moulting cycle is described. Population estimates were substantially higher with this method than with total counts, but were not dissimilar to maximum estimates obtained from strip counts. The moult method estimates the size of the entire population and is independent of the breeding cycle and breeding status of both individuals and population. It is not plagued by the problem of absenteeism encountered during most phases of the penguin annual cycle and is independent on their diel activity. The drawbacks to the method are that it is laborious and protracted, that it does not differentiate between the breeding population and the whole population, and is unsuited to some species and some habitats.     

Seasonality in diet and breeding success of the Jackass PenguinSpheniscus demersus

Summary Jackass Penguins breed throughout the year but show seasonal preferences. I examined the hypothesis that most birds breed at a time when reproductive potential is most fully realised. By using the numbers of Jackass Penguins returning to the island per 24 hour period as an index of the number of birds breeding, I found that most penguins on the island bred when chick growth was maximal and chick mortality was minimal. The diet of Jackass Penguins was determined by stomach pumping 556 birds. More than 95% of their diet, by weight, consisted of pelagic schooling fish. The local abundance of these fish seemed to determine the breeding success of the Jackass Penguin.

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Jahreszeitliche Unterschiede in Nahrung und Bruterfolg des BrillenpinguinsSpheniscus demersus

Zusammenfassung Brillenpinguine brüten zwar das ganze Jahr hindurch, zeigen aber jahreszeitliche Präferenzen. Ich prüfte die Hypothese, daß die meisten Vögel zu der Zeit nisten, wenn der höchste Bruterfolg realisiert werden kann. Die Anzahl pro 24-h-Perioden auf die Insel rückkehrender Pinguine wurde als Index für den Brutbestand betrachtet. Tatsächlich brüteten am meisten Vögel dann, als Wachstum maximal und Kükensterblichkeit minimal waren. Die Nahrung wurde durch Magenspülungen bei 556 Individuen ermittelt. Pelagische Schwarmfische machten mehr als 95 Gewichtsprozente aus. Anscheinend bestimmte die lokale Häufigkeit dieser Fische den Bruterfolg.

     

Mortality and survival of African Penguins Spheniscus demersusinvolved in the Apollo Seaoil spill: an evaluation of rehabilitation efforts

The bulk ore carrier Apollo Sea sank near Dassen Island, South Africa, on 20 June 1994 during a period of winter storms. Approximately 10 000 African (Jackass) Penguins Spheniscus demersus were oiled, collected and transported to the SANCCOB rescue centre; 5213 were released after cleaning, 4076 with flipper bands. We believe that most of the penguins oiled during this incident reached an island or the mainland alive, and that there was no mass mortality in the wild at the time of the oil spill. Birds from all parts of the breeding range were oiled, but most were from Robben and Dassen Islands. The overwhelming majority of released birds made the transition from the rescue centre to the wild successfully; 2652 had been resighted at breeding colonies within two years of their release; the cumulative number of birds was increasing steadily and an asymptote had not been reached by August 1996. There was a wide dispersal of released penguins, with recoveries and resightings over 1800 km of coastline between Algoa Bay and Walvis Bay.     

2. WADERS,DIKKOPS, COURSERS AND COMMON LARKS AT OUDTSHOORN

Eggleton, P. &; Siegfried, W. R. 1979. Displays of the Jackass Penguin. Ostrich 50:139-167.

The paper describes the displays of the Jackass Penguin Spheniscus demersus. It also covers aspects of the species' comfort behaviour. Observations were made at several islands off the South African west coast from 1973 to 1976, although most were made on 130 individually-marked adults at Bird Island (Lambert's Bay) in 1975.

The Jackass Penguin has an extensive repertoire of aggressive displays including Point, Gape, Alternate Stare, Sideways Stare, Peck and Beak Slapping. Other displays are Vibratory Head Shaking (VHS), Ecstatic Display, Mutual Ecstatic Display, several bowing displays and displays associated with copulation. The functions of the displays are discussed and comparison is made with displays in other penguins as documented in the literature. In general the displays of the Jackass Penguin resemble those of other penguins, excluding the genus Aptenodytes. There are, however, variations commensurate with the environment and habits of S. demersus.     

Responses by four seabird species to a fluctuating availability of Cape Anchovy Engraulis capensis off South Africa

In recent years, Cape Anchovy Engraulis capensis has been the most important food for four seabirds breeding in South Africa–African Penguin Spheniscus demersus, Cape Gannet Morus capensis, Cape Cormorant Phalacrocorax capensis and Swift Tern Sterna bergii. Between 1984 and 1992, biomass of spawning anchovy fluctuated between about 0.5 and 1.75 million tons. Abundance of anchovy was significantly related to numbers of chicks fledged by African Penguins, occurrence of anchovy in the diet of Cape Gannets and numbers of Cape Cormorants and Swift Terns that attempted to breed. Numbers of African Penguins and Cape Gannets that attempted breeding probably also were influenced by abundance of anchovy. African Penguins and Cape Cormorants abandoned nests when anchovy were scarce and deferred breeding until anchovy became more plentiful. Survival of immature African Penguins in a period of anchovy scarcity was enhanced by availability of South African Sardine Sardinops sagax as an alternative food. When anchovy abundance was low, Cape Gannets fed on sardine.     

A history of shifting fortunes for African penguins

Africa is home today to only a single breeding species of penguin, Spheniscus demersus (black‐footed penguin), which is endangered with extinction. Spheniscus demersus has been the only breeding species of penguin to share African coastlines with humans over the last 400 000 years. Interestingly, African penguin diversity was substantially higher before the evolution of archaic humans. The fossil record indicates that a diverse assemblage of penguin species inhabited the southern African coasts for much of the Neogene. Previous excavations have identified four distinct species in Early Pliocene coastal marine deposits. Here we extend this pattern of high diversity and report the oldest record of penguins from Africa. Seventeen penguin specimens were identified from the Saldanha Steel locality, revealing the presence of at least four distinct species in South Africa during the Miocene. The largest of these species reached the size of the extant Aptenodytes patagonicus (king penguin), whereas the smallest was approximately the size of the smallest extant penguin Eudyptula minor (little blue penguin). Recovery of Miocene penguin remains is in accordance with earlier predictions of multiple pre‐Pliocene colonizations of Africa and supports a higher level of ecological diversity amongst African penguins in the past. © 2013 The Linnean Society of London     

Sex determination of African Penguins Spheniscus demersus using bill measurements: method comparisons and implications for use

African Penguins Spheniscus demersus are sexually dimorphic; on average, males are larger than females but measurements overlap making sex determination difficult through observations alone. We developed a discriminant function, using bill length and depth from a sample of birds sexed from gonad visualisation during post-mortem, which correctly classified 93% of the individuals. Cross-validation correctly assigned 90% of DNA-sexed birds and 91% of birds sexed by partner measurement comparisons. The use of discriminant function score cutpoints, while leaving 16% and 29% of birds unclassified, improved accuracy of birds sexed by DNA to 97% and of those sexed by partner comparison to 99%. Bill depth was found to be a discriminating variable. However, two techniques for measuring bill depth are currently in use for African Penguins. While these measurements are correlated (r = 0.85), they differ on average by 1.4?mm hindering accuracy of sex determination when using a discriminant function developed from the other bill depth measurement. Exploration of adult bill morphology of birds sexed from DNA at different colonies suggests the discriminant functions can be applied throughout the African Penguins’ South African range.     

Age‐specific survival and movement among major African Penguin Spheniscus demersus colonies

Reliable estimates of survival and dispersal are crucial to understanding population dynamics, but for seabirds, in which some individuals spend years away from land, mortality and emigration are often confounded. Multistate mark–recapture methods reduce bias by incorporating movement into the process of estimating survival. We used a multistate model to provide unbiased age‐specific survival and movement probabilities for the Endangered African Penguin Spheniscus demersus based on 5281 nestlings and 31 049 adults flipper‐banded and resighted in the Western Cape, South Africa, between 1994 and 2012. Adult survival was initially high (≥ 0.74) but declined after 2003–2004 coincident with a reduction in the availability of Sardine Sardinops sagax and Anchovy Engraulis encrasicolus on the west coast of South Africa. Juvenile survival was poorly estimated, but was lower and more variable than adult survival. Fidelity to the locality of origin varied over time, but was high in adults at Robben and Dassen islands (≥ 0.88) and above 0.55 for juvenile and immature Penguins at all localities. Movement occurred predominantly during 1994–2003 and was indicative of immigration to Robben and Dassen islands. Our results confirm that a prolonged period of adult mortality contributed to the observed decline in the African Penguin population and suggest a need for approaches operating over large spatial scales to ensure food security for marine top predators.     

Growth and decline of a penguin colony and the influence on nesting density and reproductive success

Colonial breeding is characteristic of seabirds but nesting at high density has both advantages and disadvantages and may reduce survival and fecundity. African penguins (Spheniscus demersus) initiated breeding at Robben Island, South Africa in 1983. The breeding population on the island increased in the late 1990s and early 2000s before decreasing rapidly until 2010. Before the number breeding peaked, local nest density in the areas where the colony was initiated plateaued, suggesting that preferred nests sites were mostly occupied, and the area used by breeding birds expanded. However, it did not contract again as the population decreased, so that nesting density varied substantially. Breeding success was related positively to the prey available to the breeding birds and negatively to local nest density, particularly during the chick-rearing period, suggesting a density-dependence operating through social interactions in the colony, possibly exacerbated by poor prey availability when the breeding population was large. Although nest density at Robben Island was not high, nesting burrows, which probably reduce the incidence of aggressive encounters in the colony, are scarce and our results suggest that habitat alteration has modified the strength of density-dependent relationships for African penguins. Gaining a better understanding of how density dependence affects fecundity and population growth rates in colonial breeders is important for informing conservation management of the African penguin and other threatened taxa.     

Identification of land predators of African Penguins Spheniscus demersus through post-mortem examination

The African Penguin Spheniscus demersus is an endangered seabird endemic to southern Africa, and killing sprees by terrestrial predators have been one of the main threats for its mainland colonies. The methods employed to manage predators may differ depending on the species involved, therefore the implementation of strategies to limit the impacts of predation relies on the correct identification of the culprit predator. We report and quantify the lesions seen in African Penguins killed by four species of terrestrial predators: Caracal Caracal caracal (52 kills), Leopard Panthera pardus (27 kills), Domestic Dog Canis lupus familiaris (10 kills), and Cape Grey Mongoose Galerella pulverulenta (4 kills). We discuss patterns of necropsy findings that can be used to identify the predator species involved. Traditional forensic methods are useful tools to direct species-specific management actions for the conservation of the African Penguin and other seabirds so that effective mitigating measures can be deployed quickly to prevent further losses. It should be borne in mind, however, that the age, size and previous hunting experience of the predator are likely to influence the pattern of lesions that will be observed, and not all carcasses will have hallmark lesions or recognisable bite marks.     

Postfledging parental care and unexpected foraging behaviour of juvenile Sooty Terns Onychoprion fuscata in the southern Mozambique Channel

The Berlese funnel method, and its variations, is commonly used for the extraction of arthropods from various substrates such as nest material. However, little is known about its effectivity in extracting ectoparasites from penguin nests. This study aimed to assess the efficacy of a modified Berlese funnel method in extracting ectoparasites from African Penguin Spheniscus demersus nests and to determine differences in extraction capacity across parasite taxa and life stages. African Penguin nests (n = 278) were sampled at five penguin colonies along the south-west coast of South Africa in 2017. Nest samples were subjected to a modified Berlese funnel method with naphthalene as a repellent. Thereafter, all remaining ectoparasites were removed by hand sorting. Ectoparasite abundance was positively correlated between the two extraction methods (Spearman’s r = 0.73–0.89). Compared to total counts, flea (combined life stages and larvae) and total ectoparasite abundance and prevalence were significantly lower with the modified Berlese funnel method. In addition, adult flea and tick prevalence (but not abundance) was significantly lower with the modified Berlese funnel method compared with total counts. The modified Berlese funnel method fails as a quantitative method and can only provide a crude indication of the incidence of ectoparasites in penguin nests.     

7. SHORT NOTES FROM MEMBERS

Cooper, J., Ross, G. J. B. &; Shaughnessy, P. D. 1978. Seasonal and spatial distribution of Rockhopper Penguins ashore in South Africa. Ostrich 49:40-44. There are 30 records of Rockhopper Penguins Eudyptes chrysocome ashore in South Africa. Both the southern subspecies E.c. chrysocome, and the northern subspecies E.c. moseleyi have been recorded. The northern subspecies has occurred more frequently. Most records are of moulting juveniles in January and February. Records of adult birds are more scattered throughout the year. Rockhopper Penguins in South Africa have been recorded only south of 30S. Birds of the northern subspecies probably originate from South Atlantic islands (Tristan da Cunha group and Gough). Birds of the southern subspecies are probably from the Prince Edward Islands.     

BREEDING NOMADISM IN SOUTHERN AFRICAN SEABIRDS-CONSTRAINTS,CAUSES AND CONSERVATION

Crawford, R.J.M., Dyer, B.M. & Brooke, R.K. 1994. Breeding nomadism in southern African seabirds-constraints, causes and conservation. Ostrich 65:231-246.

Fourteen species of seabirds representing three orders and five families breed in southern Africa. Nomadism in the breeding populations of 13 of these seabirds is examined. African Penguins Spheniscus demersus, Cape Gannets Morus capensis. Bank Cormorants Phalacrocorax neglectus, Whitebreasted Cormorants P. carbo and White Pelicans Pelecanus onocrotalus show strong fidelity to specific localities. Caspian Terns Sterna caspia change breeding localities at a low frequency; Cape Cormorants P. capensis, Hartlaub's Gulls Larus hartlaubii and Swift S. bergii and Roseate S. dougallii Terns at a higher frequency. At some localities, Bank Cormorants remain at the same breeding sites for extended periods, whereas Crowned Cormorants P. coronatus, Whitebreasted Cormorants, Kelp Gulls L. dominicanus, Hartlaub's Gulls, Damara Terns S. balaenarum, Swift Terns and Roseate Terns all alter breeding sites. Where space is not limiting, African Penguins may also change sites. Constraints on nomadism include strong attachment to traditional breeding localities, unwillingness to roost at non-breeding localities, and lack of suitable alternative nesting localities. Amongst causes of nomadism are excessive disturbance by humans and South African Fur Seals Arctocephalus pusillus and competition for breeding space, which have resulted in even the least nomadic of the species changing their breeding locations. Regularly nomadic species are likely to respond to environmental cues that enable them either to reduce cost of breeding or to increase reproductive output. Therefore, they are potentially useful indicators of ecological health. Nomadic breeders additionally have the ability to establish new breeding colonies. Some species have used artificial structures to expand their breeding range, and probably also to increase their overall populations. However, nomadic tendencies complicate the conservation of breeding activities. By contrast, breeding species with strong fidelity to traditional localities are more easily protected.     

Gill Memorial Medal Address Holding the mirror up to nature

Since the early 1980s, there have been large decreases in numbers breeding in South Africa of three seabirds that compete with fisheries for food: African Penguin Spheniscus demersus, Cape Cormorant Phalacrocorax capensis and Bank Cormorant P. neglectus. By contrast, two other species that compete with fisheries but which have a larger foraging range when breeding or are nomadic between breeding localities, Cape Gannet Morus capensis and the nominate race of Swift Tern Thalasseus bergii bergii, have increased. Five seabirds that do not compete with fisheries for prey have maintained stable populations or increased. The decreases in the three species have led to deterioration in the overall conservation status of South Africa's seabirds, of which 10 of 15 species (67%) are presently classified as Threatened or Near-threatened, including six of the seven species that are endemic to the Benguela ecosystem off western southern Africa.     

NOTE ON THE CAPE THICKKNEE

Concerns have been expressed over the impact of flipper banding on the survival and reproductive performance of penguins. This study compared the breeding success of banded and unbanded African Penguins Spheniscus demersus at Boulders Beach, South Africa, in 2006. It was based on 100 nests; 50 had at least one banded adult and 50 had no banded adults. Besides flipper banding, other variables considered were extent of vegetation cover, proximity to tourist path, burrow depth, and either sand or clay substratum. There were no significant differences in breeding success between the different nest types or between banded and unbanded penguins, suggesting that once an individual reaches the level of fitness required to breed, banding does not affect the outcome of breeding by African Penguins.