When we think of causes concerning the decline of certain animal species, one of the biggest factors that affect them are human activities. However, that is not always the case. Some populations can fluctuate in size because of natural environmental events .
|Galapagos penguin drying wings, photo from www.arkive,org|
A Galapagos penguin (Spheniscus mendiculus) can be found at the northern part of the equator of the
They are known as one of the smallest penguin species that has an average
height of around 50 centimeters.  However because of certain events such as
the El Niño Southern Oscillation (ENSO), in 1980 this resulted to a decline of
its population by 77%. Although 50% of its population were able to recover by
1995, the 1997 to 1998 El Niño caused its population to further reduce to 65%.  The ENSO also introduces a strong negative
effect on the behaviour, breeding, and reproduction of the penguins. It was
concluded that breeding periods that occur during El Niño result to the failure
of the survival of their nests. Galapagos penguins depend on the upwelling of
the cool nutrient rich oceanic water that supports the small schooling fish
that they feed on.  The oceanic conditions have resulted to a decline of food
availability due to the increase in its temperature over the past years which
have overall reduced the population to more than 50% comparing to its
population during the 1970’s. Galapagos Island
At present, its population is now around 1800 individuals.  Galapagos penguins are classified as Endangered (EN) according to the IUCN red list.
To know more about them, visit SeaLifeBase.
 Akst, E.P., Boersma, P.D., & Fleischer, R.C. (2002) A comparison of genetic diversity between the Galapagos Penguin and the Megallanic Penguin. Conservation Genetics 3:375-383
 Ludwig, D. (1996) The Distribution of Population Survival Times. The American Naturalist (147)4:506-526
 Boersma, P. (1998) Population trends of the Galapagos Penguin: Impacts of El Niño and La Niña. The Condor (100)2:245-253
 Lacy, R.C., Meile, R.J., Parker, P.G., Vargas, F.H. (2013) Modeling Plasmodium Parasite arrival in the Galapagos Penguin (Spheniscus mendiculus) The Auk 130(3):440-448
 BirdLife International 2012. Spheniscus mendiculus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 15 April 2015.