The Jackass Penguin (Spheniscus
demersus): Major Threats and
Conservation Efforts
Introduction
The
jackass penguin, Spheniscus demersus, is facing endangerment due to
rapid population decline (see photo). This decrease in numbers is largely due
to food shortages, oil spills, and habitat disruption (IUCN). Conservation of
jackass penguins is important because it is the only species of penguin that
breeds in Africa. Additionally, this species serves as both prey and predator,
and therefore has a key role in the ecosystem. The purpose of this post is to raise
awareness about the major threats to Spensicus demersus and to evaluate
the conservation efforts that have been implemented thus far.
The Endangered Jackass Penguin
Spheniscus demersus is
a species of medium-sized penguin that is endemic to Southern Africa. It is a
marine bird that usually resides in seas within 40km of land, but comes ashore
every four months to breed and molt (IUCN). The minimum viable
population for jackass penguins was calculated to be more than 40,000 pairs in
2001 (Crawford, 2001). Breeding populations are found in South Africa and
Namibia on 25 islands and 4 mainland sites (IUCN). The number of jackass penguins
breeding in South Africa dropped from
56,00 pairs to about 21,000 pairs in the eight-year span from 2001 to 2009 (Crawford,
2011). Even after including Namibian breeders, the global population of the species
is still over 10,000 pairs lower than the minimum population size which classifies
the jackass penguin as endangered.
Major Threats
Habitat Disruption
Humans
have had a huge negative impact on the jackass penguin. The initial huge
decline of the jackass penguin is attributed to major guano collection by
humans for use as fertilizer in the 1800s (Roach, 2012). Because the penguins
burrow in a built-up layer of guano to make their nests, without this, the
birds are forced to nest on the surface where eggs are very susceptible to
predation and the elements.
Another major contributor
to the decrease of jackass penguins is egg collecting. Since they are
considered a delicacy, penguin eggs were harvested by humans for consumption.
Worse still, eggs found in nests would be smashed a few days prior to gathering
in order to ensure the freshness of the ones taken (Roach, 2012). To give a
sense of the extent of the damage this caused, from the 1920s to 1960s almost
half of the eggs produced in one main nesting site were harvested (Roach, 2012).
Fortunately, this practice was outlawed in 1967.
Further disruption of the jackass
penguin’s habitat has been caused by tourism. People can accidentally collapse
nests and induce stress in the penguins. Although they don’t pose a major
threat, if present in large numbers, tourists can even prevent younger birds
from breeding (IUCN).
Food Shortage
Jackass penguins
primarily prey on anchovies (Engraulis encrasicolus) and sardines
(Sardinops sagax). In order to obtain meals, the birds have to compete
for these fish with several predators, such as the fur seal Arctocephalus
p. pusillus. This is becoming an even greater challenge for the penguin as
the sardine and anchovy populations in their habitat become depleted due to
overexploitation by commercial fisheries (Crawford, 2001). Also, it is
speculated that the sardine and anchovy populations are lower because they are
undergoing a range shift due to climate change (Koenig, R).
The significance
of anchovy and sardine populations to the jackass penguin was shown in a 2008
paper by Crawford, et al. In this study, researchers found the relationship between
the breeding success of jackass penguins and the combined spawner biomass of
these anchovy and sardine species from 1989 to 2004. There is a distinct
positive correlation between the abundance of the fish and the number of chicks
hatched, implying that a reduction of anchovy and sardine populations due to
overfishing will also decrease the fecundity of the jackass penguins. In
addition, commercial fishing increases the mortality of
the jackass penguin since many birds are caught and killed in fishing nets (IUCN).
Oil Spills
Jackass
penguins have been a major victim of oil spills, namely the Apollo Sea spill in
1994 and the Treasure oil spill of the coast of West Africa in 2000 (Wolfaardt,
2008). Getting “oiled" is a potentially fatal condition for the jackass penguins since it disrupts the natural insulating properties of the birds’ specialized feathers. Additionally, the preening of oiled feathers can cause consumption of oil in toxic amounts (Konings, 1997). Despite major rescue efforts to prevent this outcome, about 30,000 individuals died as a result of the Apollo Sea and Treasure spills (Nel and Whittington 2003). The number of
casualties is three-fourths of the estimated
minimum population size for Speniscus
demersus, which demonstrates how severely oil spills impact the viability
of the species. This figure is even likely to be an underestimate, since many unhatched
penguins left behind by rescued parents were not counted as fatalities. A clip from
BBC wildlife show 'African Penguin: Cool Bird in a Hot Spot' that depicts the hardships
penguins face due to oil spills can be found here: https://www.youtube.com/watch?v=tsX08folMhY.
 |
| Photo by Martin Harvey, World Wildlife Fund |
Even in the absence of major spills near South Africa, jackass penguins are
still found covered in oil (pictured below) due to illegal oil dumping from
ships (IUCN). This leaves breeding localities on shores adjacent to shipping
ports especially at risk to oil washing ashore.
Conservation Efforts
Counteracting Food Shortage
One way
of preventing the depletion of the jackass penguin’s primary food source,
anchovies and sardines, is through establishment of Marine Protected Areas
(MPA). A recent study has shown that penguins in an area closed to fishing
expend less energy searching for fish than those in an unregulated area (CNRS,
2012). Another strategy is to increase regulation of fisheries near South
Africa in order to cease overexploitation. Based previous studies, it would be
ideal to use these techniques to maintain a combined biomass of anchovy and sardine populations above 4 million tons to ensure decent penguin breeding success (Crawford, 2008).
Preventing Habitat Disruption
In order to prevent further habitat disruption, all jackass
penguin breeding localities in South Africa are protected; some are even
national parks. In addition, collection of guano and eggs is now prohibited
within penguin colonies. An innovative strategy has been implemented on an island
resident to jackass penguins in an attempt to reduce egg mortality and the
impact of depleted guano. Conservation biologists have put in place fiberglass
igloos (pictured) for the birds to use as nesting sites (IUCN). These igloos
protect eggs from gulls and other predators when parents are absent, while also
serve as shelter from heat (Orlando Sentinel, 2009).
Rescue and Recovery from Oil
Rehabilitation of
jackass penguins affected by oil spills has been fairly successful. Tens of thousands of oiled birds have
been captured, cleaned, and reintroduced into their habitat after spills.
However, even if they survive contact with oil, 28% of the penguins
reintroduced after cleansing are unable to breed (Nel, 2003). Therefore, the
most effective preventative strategy seems to be evacuating un-oiled penguins
to minimize their risk of becoming contaminated in the first place (Wolfaardt,
2008).
A
recent study by Barham et al. measured the viability of reintroduced female
chicks that were hand-reared after being orphaned from the Treasure oil spill. Figure
2 shows the annual survival rate from 2000 to 2005 on Robben Island.
Researchers predicted that about 135 out of a 1,000 hand-reared female chicks were
able to survive to breeding age (Barham, 2008). This study provides promising
evidence that hand-rearing chicks can be an effective tool for helping chicks
that are orphaned during oil spills or naturally abandoned by their parents.
Operations for rescuing
at-risk individuals must be carefully planned since they potentially bring harm
to the penguins. For instance, the process of searching for and collecting oiled
or abandoned penguins can cause long-term disturbance of colonies and their
habitats (Barham, 2008). Also, excessive handling of birds during transport and
rehabilitation induces a high level of stress that leads to unnecessary deaths (Konings,
1997). Therefore, it is important to weigh the harm versus help caused by any
conservation actions.
Conclusion
The population of
the African penguin, Spheniscus demersus,
is currently below the estimated minimum viable population size and still
declining. The species is endangered largely due to food scarcity, oil
contamination, and habitat destruction. It is important to conserve this species
because it is beneficial to the ecosystem of South Africa and also to humans through
ecotourism. Conservation plans are currently in place to try to reduce and
prevent the impact of these three major threats. The potential implications of
all conservation actions must be evaluated, since there are cases where they
can be more harmful than helpful. It is important to plan for future ways of
preserving the African penguins, such as hand-rearing chicks and relocating
birds to areas with greater food availability. Preventative measures such as
reducing oil spillage and overfishing should also be taken into consideration.
One of the
challenges faced by these conservation efforts of the Jackass Penguin is sheer
cost. For instance, the entire Apollo Sea penguin rescue operation cost
approximately three-hundred thousand US dollars (Wolfaardt, 2008). However, by
increasing public awareness through education and media such as this blog post,
perhaps enough money can be raised to save Spheniscus
demersus from extinction and conserve biodiversity.
Works Cited-Barham,PJ. Les G. Underhill, Robert J. M. Crawford, Res Altwegg, T. Mario Leshoro, Duncan A. Bolton, Bruce M. Dyer and Leshia Upfold. “The efficacy of handrearing penguin chicks: evidence from African Penguins ( Spheniscus demersus) orphaned in the Treasure oil spill in 2000.” Bird Conservation International, 18 (2008): 144152
-BirdLife International 2012. Spheniscus demersus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <
www.iucnredlist.org>. Downloaded on 06 November 2012.
-CNRS (Délégation Paris Michel-Ange). "Marine protected areas: A solution for saving the penguin." ScienceDaily, 16 Feb. 2010. Web. 28 May. 2013.
-Crawford, RJM, R Altwegg, BJ Barham, PJ Barham, JM Durant, BM Dyer, D Geldenhuys, AB Makhado, L Pichegru, PG Ryan, LG Underhill, L Upfold, J Visagie, LJ Waller, and PA Whittington. "Collapse of South Africa's Penguins in the Early 21st Century." African Journal of Marine Science, 33.1 (2011): 139-156.
-Crawford, R J. David, L. J. Shannon, J. Kemper, N. T. W. Klages, J-P. Roux, L. G. Underhill, V. L. Ward, A. J. Williams, A. C. Wolfaardt. “
African penguins as predators and prey – coping (or not) with change.”
South African Journal of Marine Science 23.1 (2001)
-Crawford, R. J, L Underhill, J Coetzee, T Fairweather, L Shannon, and A Wolfaardt. “Influences of the Abundance and Distribution of Prey on African Penguins Spheniscus Demersus off Western South Africa.” African Journal of Marine Science, 30.1 (2008): 167-175.
-Frost, P G, Siegfried W R, Cooper J, “Conservation of the jackass penguin (Spheniscus demersus (L.))”, Biological Conservation, 9.2 February (1976): 79-99
-Koenig, R. “African Penguin Populations Reported in a Puzzling Decline” Science 2 March 2007: 315 (5816), 1205.
-Konings, C. "Coastal Oil Spill: Apollo Sea Shipping Disaster — June 1994." Journal Of Contingencies & Crisis Management 5.2 (1997): 118.Academic Search Premier. Web. 28 May. 2013.
-Nel, Deon C., and Phil Whittington. Rehabilitation of Oiled African Penguins: A Conservation Success Story. Stellenbosch, South Africa: BirdLife South Africa, 2003. Print.
Orlando Setinal. "Save South Africa's Penguins - Give Them a Home Animal” Orlando Sentinel."Save South Africa's Penguins. N.p., 30 Mar. 2009. Web. 28 May. 2013.
http://blogs.orlandosentinel.com/features_lifestyle_animal/2009/03/save-south-africas-penguins-give-them-a-home.html
-Roach, John. "Africa's Penguins Still Reeling From "Guano Craze"" National Geographic. National Geographic Society, 16 Aug. 2004. Web. 28 May. 2013. <http://news.nationalgeographic.com/news/2004/08/0816_040816_african_penguin.html>.
-Wolfaardt, A, L Underhill, R Altwegg, J Visagie, and A Williams. "Impact of the Treasure Oil Spill on African Penguins Spheniscus Demersus at Dassen Island: Case Study of a Rescue Operation." African Journal of Marine Science, 30.2 (2008): 405-419.
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