Saturday 1 November 2014

Hand rearing African Penguin chicks in the Western Cape.

African Penguins, Spheniscus demersus, breed at a number of sites along the coasts of South Africa and Namibia. The species is considered to be Endangered under the terms of the InternationalUnion for the Conservation of Nature’s Red List of Threatened Species, following a 70% drop in the total population of the Birds between 2001 and 2013. This has been attributed to changes in the distribution and availability of the Penguin’s two main prey species, the Sardine, Sardinops sagax, and the Anchovy, Engraulis encrasicolus, in part due to competition with the local purse-seine fishery.

The populations of African Penguins near Cape Town were hit by two large oil spills in 1994 and 2000, resulting in the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) capturing a large number of adult birds for de-oiling, and the chicks of these birds for hand rearing (since the adult birds were unable to feed their young while being treated for oil contamination). This hand rearing procedure was largely successful, and was from 2001 onwards extended to abandoned chicks from Robben and Dyer Islands.

 African Penguins, Spheniscus demersus. SANCCOB

Chicks may be abandoned due to the death of their parents, flooding of the nest site or because the parents enter their annual mount before the chicks are ready to fledge. The annual moult in African Penguins occurs at the beginning of summer, and cannot be delayed, adults with unfledged chicks beginning to moult in response to moulting in other birds around them. Chick fledging, on the other hand, is driven by food availability, with chicks that have not received sufficient food failing to fledge before the onset of the moult being abandoned. African Penguins are long-lived birds which typically rear two broods per year, so the adult birds will not endanger their health (and potential future breeding success) for these late fledging birds.

In a paper published in the journal PLoS One on 22 October 2014, Richard Sherley of the Animal Demography Unit and Marine Research Institute at the University of Cape Town, the Bristol Zoological Society and the Environment and Sustainability Institute at the University ofExeter, Lauren Waller of the Animal Demography Unit and Marine Research Institute at the University of Cape Town and CapeNature, Venessa Strauss of SANCCOB, Deon Geldenhuys also of CapeNature, Les Underhill, also of the Animal Demography Unit and Marine Research Institute at the University of Cape Town and Nola Parsons, also of SANCCOB discuss the results of two large-scale interventions on Dyer Island, following the mass abandonment of chicks be adults that had begun to moult before they fledged in 2006 and 2007.

In 2006, 113 chicks had been collected from Robben Island, 34 from Stoney Point and 19 from Dyer Island prior to 15 October, when the adults on Dyer Island began to go into moult en masse, and the decision was made to remove all the surviving chicks from Dyer Island for hand rearing, a total of 668 chicks being collected between 16 and 21 October. Not all of the adults on Dyer Island had entered moult at the time when this occurred, but since moulting in adults is triggered by the proximity of moulting in nearby adults, and the removal of large numbers of chicks was deemed to be sufficiently disruptive to the life of the colony that the abandonment of further chicks was likely, the decision was made to remove all chicks from the colony.

In 2007, 7 chicks had been removed from Robben Island and 47 from Stoney Point by 27 October, when the adults on Dyer Island again began to go into moult en masse, and it was again decided to remove all remaining unfledged chicks from the island; on this occasion 427 chicks being collected.

Map of the Western Cape, South Africa, showing the locations of the main African penguin breeding colonies (black circles) mention in the text and the location of SANCCOB (black square) in relation to Cape Town (white circle). Sherley et al. (2014).

Artificial feeding can be a problem for some bird species, but Sherley et al. report that African Penguins respond well to the procedure. This is probably due to the natural biology of the birds; after an initial period of guarding when the chicks are very young both parents engage in collecting food for the young, which spend extended periods of time sitting alone waiting to be fed, and seem to be largely indifferent to who (or what) feeds them as long as food arrives. The captive birds accepted a mixture of fish-paste laced with vitamins and whole fish without any problems.

Disease control at in captive reared Penguins proved to be much more problematic. Many of the captive birds were afflicted by bacterial and fungal infections of the respiratory system, probably caused by overcrowding at the treatment facility (the rearing of this large a number of chicks had not been attempted before, and was not anticipated prior to the first mass-abandonment). The birds were also afflicted by two insect-borne diseases, avian pox and avian malaria, and the treatment facility attracted large numbers of Flies and Mosquitoes. A variety of screens, traps and insecticides were used to try to control the insects, with limited success. In 2008 a new fly screen system was introduced that appears to be much more effective, but no mass abandonment of chicks has occurred since then, so it is unclear how well the new system would cope with such an occurrence. Finally many of the chicks were afflicted with bumblefoot (pododermatitis) a disease of the feet which is not usually fatal but which is highly unpleasant for the chicks. This can be easily treated by making the chicks walk through water laced with disinfectant and providing them with different substrates on which to stand, but the facility was not equipped to do this for the large number of birds admitted in 2006 and 2007.

Of the 841 chicks admitted in 2006, 766 were subsequently released, and of the 481 chicks admitted in 2007, 351 were released. Since chicks are known to move freely between populations before choosing a mate and a nesting site, rather than strictly returning to the parental nesting site to breed, it was not deemed necessary to return all the chicks to Dyer Island for release, and the chicks were released variously from Robben Island and Dyer Island, or in some cases into the sea near Robben Island. All the chicks were ringed for subsequent identification, and chicks released in 2006 and 2007 have subsequently been sighted breeding on Dyer Island, Robben Island, Dassen Island and at Stoney Point. It is estimated that 14% of the captive reared chicks went on to enter the breeding population, which compares favourably with the 11% of chicks that are expected to enter the breeding population from naturally reared broods.

Sherleyet al. observe that Penguins seem to be particularly well suited to captive rearing programs, and recommend that the process could be used to increase numbers of other endangered Penguin species reaching maturity, and potentially to re-establish historic breeding populations that have been lost or establish new colonies as a defence against shifting prey-fish distributions. However they caution that extreme attention must be paid to disease control in such programs, to avoid introducing diseases to the wild population that could further accelerate the decline of already threatened species.

See also…

An operation to recover oil from a ship which sank of the coast of Richards Bay, KwaZulu Natal, on Monday 19 August 2013, is due to begin today (Thursday 22 August). The VS Smart, a 230 m Greek...

Penguins are thought to have originated in New Zealand and subsequently spread to other parts of the Southern Hemisphere. Certainly both modern and fossil Penguins are at their most diverse in New Zealand. A large number of fossil penguins have been described from New Zealand, although, as is often the case with fossil birds, many of these are fragmentary in nature.

A single species of Penguin, Spheniscus demersus, or the Blackfooted Penguin, lives in Southern Africa today, though two species, Nucleornis insolitus and Inguza predemersus are known to have lived there in the Early Pliocene. It has generally been assumed that the modern Penguins are descendants of the fossil penguins, though since they are also clearly closely related to other Penguins of the genus Spheniscus...

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