Pa Whittington

Collapse of South Africa's penguins in the early 21st century

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.

Recent distributional changes of seabirds in South Africa: is climate having an impact?

There have been recent changes in the distributions of several seabirds in South Africa. In the mid-1990s, breeding of Leachs 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 Hartlaubs 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 Africas 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.

Recent trends in numbers of four species of penguins at the Prince Edward Islands

Four species of penguin breed regularly at South Africas Prince Edward Islands: king penguin Aptenodytes patagonicus, gentoo penguin Pygoscelis papua, macaroni penguin Eudyptes chrysolophus and southern rockhopper penguin E. chrysocome. In December 2008, it was estimated that some 65 000 pairs of king penguins were incubating eggs at Marion Island, the larger of the two islands in the group, and 2 000 pairs at Prince Edward Island. At Marion Island from 1987 to 2008, there was no long-term trend in numbers of king penguin chicks that survived to the end of the winter period, but there was considerable fluctuation in chick production in the 1990s. It was roughly estimated that on average 88% of king penguin chicks survived the winter period (from April to September/October). Numbers of gentoo penguins at Marion Island decreased from more than 1 300 pairs in the mid-1990s to fewer than 800 pairs in 2003, and then increased to almost 1 100 pairs in 2008 as breeding success improved. Between 1994/1995 and 2008/2009, numbers of macaroni and southern rockhopper penguins at Marion Island decreased by about 30% and 70% respectively. In 2008/2009, some 290 000 pairs of macaroni penguins bred at this island, mostly in two large colonies where there was a progressive decrease in the density of nests. At both these colonies, decreases in numbers breeding followed outbreaks of disease. Inadequate breeding success has influenced the decreases of macaroni and rockhopper penguins. In 2008/2009, some 42 000 pairs of southern rockhopper penguins bred at Marion Island and 12 000 pairs of macaroni penguins and 38 000 pairs of southern rockhopper penguins at Prince Edward Island.

Abundance and distribution of avian and marine mammal predators of sardine observed during the 2005 KwaZulu-Natal sardine run survey

Opportunistic observations to determine the relative abundance and distribution of marine mammal and seabird predators of sardine Sardinops sagax were carried out during a dedicated multidisciplinary research survey off the South African east coast in June and July of 2005 that was timed to coincide with the annual sardine run. Associations between different predator species, between predators and clupeoids, and between predators and oceanographic variables, were examined. Species’ distributions were primarily separated by latitude and distance from shore. Brydes whale Balaenoptera edeni, African penguin Spheniscus demersus, Cape cormorant Phalacrocorax capensis and West Coast round herring Etrumeus whiteheadi were predominantly found in the cool southern part of the survey region. Peak sardine run activity occurred within 4 km of shore at the northward limit of a strip of cool water (<21 °C) stretching along the East Coast. The principal predators associated with this activity were common dolphins Delphinus capensis and Cape gannets Morus capensis, and their nearshore distribution was associated with sardine and East Coast round herring E. teres. Few clupeoids were encountered along the KwaZulu-Natal continental shelf, although patches of high sardine abundance were recorded near the shore immediately south of Durban. It is clear that during the 2005 survey the sardine run terminated in this region, probably as a result of the nearshore intrusion of warm water from the Agulhas Current.

Review of the rescue, rehabilitation and restoration of oiled seabirds in South Africa, especially African penguins Spheniscus demersus and Cape gannets Morus capensis, 1983–2005

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 Africas oil spill management strategy, and every effort should be made to further improve both of these aspects.

Patterns of immigration to and emigration from breeding colonies by African penguins

Of over 20 000 African penguins Spheniscus demersus that had been flipper-banded as chicks between 1978 and 1999, 2% of those re-sighted after fledging settled to breed at non-natal colonies. This represented 14% of the banded birds that were subsequently recorded breeding. Only one of these immigrants had previously been recorded breeding at its natal colony, the rest presumably being first-time breeders. The largest proportions of banded chicks that emigrated came from Dyer Island on the south coast of South Africa, all of which settled at colonies to the west or north. Penguins emigrating from Namibian breeding colonies either relocated to the Western Cape of South Africa or settled at colonies farther to the north in Namibia. Emigration and immigration of African penguins are thought to be driven by changes in the distribution and availability of their prey. Eight penguins that were banded in adult plumage were found to have attempted breeding at more than one locality. All were survivors of the Apollo Sea oil spill of 1994 and had been cleaned and released by the Southern African Foundation for the Conservation of Coastal Birds. This is thought to be the first documented evidence of attempted breeding by African penguins at more than one locality.

Longevity, inter-colony movements and breeding of Crested Terns in South Africa

Abstract The nominate race of the Crested Tern, Sterna bergii bergii, first breeds when aged three years, but may not be fully recruited to breeding colonies until six years old because many birds do not breed in years of food scarcity. A 21-year-old bird breeding at Dassen Island was the oldest record for the species. There are 109 records in South Africa of birds alive when aged 15 years or older. Of birds whose colony of origin was known, 18% of those breeding and 27% of those present at colonies were at their natal localities. Most cohorts bred at several localities and breeding at most colonies was by birds fledged at several localities. Crested Terns in the Western Cape mainly breed between January and June. Most eggs are laid between January and April. Mean clutch size is 1.02 eggs. At Robben Island in 1987 and 1988 the average number of chicks fledged per breeding pair was estimated to be between 0.48 and 0.59.

A changing distribution of seabirds in South Africa—the possible impact of climate and its consequences

In the southern Benguela ecosystem off South Africa, there were recent shifts to the south and east in the distributions of three forage resources (anchovy, sardine, rock lobster), which probably were influenced by environmental change although fishing too may have played a part. In this study, we review information on trends in distributions and numbers of eight seabirds breeding in South Africa. For five species that feed predominantly on anchovy, sardine or rock lobster, their populations off northwest South Africa decreased markedly. For three of these species, which exhibit behavioural inertia and have restricted foraging ranges when breeding (African penguin, Cape cormorant, bank cormorant), there were large decreases in their overall populations in South Africa. Conversely, for two showing more plasticity and able to range over wide areas or move between breeding localities (Cape gannet, swift tern) there were increases. It is thought that movement of forage resources away from the northern islands led to a mismatch in the distributions of breeding localities and prey of dependent seabirds off western South Africa and to attempts by several species to establish colonies on the southern mainland closer to food resources. There also were shifts to the south and east in the distributions of three seabirds that do not compete with fisheries for prey (crowned cormorant, white-breasted cormorant, kelp gull), suggesting some environmental forcing, but decreases of these species off northwest South Africa were less severe and populations in South Africa remained stable or increased in the long term. It is likely, because many fishing plants are located in the northwest, that there was increased competition between seabirds and fisheries for prey as forage resources moved south and east. Potential interventions to mitigate the adverse impacts of distributional changes for seabirds include allocations of allowable catches of shared forage resources at regional levels,

A tale of two islands: contrasting fortunes for Subantarctic skuas at the Prince Edward Islands

Subantarctic skuas Catharacta antarctica are key predators of burrowing petrels at sub-Antarctic islands, and can be used to monitor the health of burrowing petrel populations. A survey of skuas at the Prince Edward Islands was conducted during December 2008, repeating a previous survey in December 2001. Prince Edward Island (46 km2) remains free of introduced mammals, whereas Marion Island (290 km2) had a feral population of cats from the 1950s to 1980s, and still supports a large population of introduced house mice Mus musculus. Breeding skuas were more widespread, occurred at greater densities and extended to higher elevations at Prince Edward Island than Marion Island. Prince Edward Island also supported twice as many non-breeding birds. Burrowing petrels comprised 96% of prey in skua middens at Prince Edward Island compared to only 22% on Marion Island where penguins are more important. The numbers of breeding pairs at Prince Edward Island increased from 2001 to 2008, probably as a result of better coverage in 2008, whereas the number of skua nests on Marion Island was barely half that counted in 2001, continuing an apparent decrease in this species at Marion Island since the 1980s. There is no evidence that removal of cats from Marion Island in the early 1990s has benefited the major native predator of burrowing petrels.

Patterns of movements of the African penguin in South Africa and Namibia

The direction, distance and seasonal patterns of movements of African penguins Speniscus demersus between breeding colonies were investigated for birds that had been flipper-banded between 1970 and 1998. These were comprised of 3 986 penguins banded as chicks at nests, 1 672 banded as adult birds at breeding colonies and 4 691 adult penguins that had been oiled, sick or injured and subsequently rehabilitated. An analysis of observations of flipper-banded penguins in KwaZulu-Natal, Eastern Cape, Western Cape and Northern Cape provinces of South Africa and in Namibia, showed that 35% of birds banded as chicks and 9% of those banded as adults had visited mainland sites or breeding colonies, other than the birds own natal or breeding colony. Penguins banded as chicks at Eastern Cape colonies and sighted within two years of banding exhibited a marked clockwise movement around the coast. Penguins from all regions that had been banded as chicks and subsequently found dead also showed a clockwise pattern of movements, whereas live resightings of birds banded as chicks in the Western Cape or at Namibian colonies did not reveal a significant directional trend in their movements. Penguins banded as adults at Eastern Cape colonies moved in a clockwise direction around the coast but there was no obvious pattern shown by adults banded at colonies in the other regions or of rehabilitated birds. Most re-sightings of penguins banded as chicks were made in spring or summer, but there was no seasonal pattern associated with the re-sightings of penguins banded as adults. Distances travelled by penguins banded as chicks averaged greater than for those banded as adults. Juvenile birds usually return to their natal colony, but it is evident that some young birds have the capacity to settle and breed at non-natal colonies.