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…
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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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