People Vs Penguins
Are we responsible for penguin decline?
To determine the greatest threats to penguins, this study used species specific literature reviews, which included contributions from specialists. Looking at the main anthropogenic factors threatening each of the 18 species of penguins over the past 250 years (List of penguin species, their location and ICUN status can be found in the publication).
Endangered/venerable species of penguin mainly occur in South America, Africa, New Zealand and the Sub Antarctic. Many of these species have a limited geographic range and/or small populations. The causative factors for penguin decline are often unknown.
The results of this study are split into categories, I have made points on the findings using the headings in the publication. Please see the publication for more detail.
- Harvesting for oil, skin, feathers and their use as bait
- Several species of penguin have previously been harvested for oil, skin and feathers
- This occurred where species were abundant and so led to a decline
- Penguin harvesting and use as bait has now become rare
- Historically taking or moving eggs was common
- This is now considered an outdated practice but does still occur
- The impact on population size is unknown
- Terrestrial habitat degradation
- Possibly a major threat to Sub Antarctic, temperate and tropical penguins
- Grazing animals which have been introduced in some areas has reduced the vegetation cover
- The introduction of predators has led to the killing of both adult and young penguins
- Disturbance by tourists and scientists
- Marine pollution
- A major cause of death in penguins is oil pollution
- They are extremely susceptible to oil
- Oils spills from shipwrecks still occur off South America and South Africa where there are penguin colonies
- Marine debris, coastal mining and heavy metal accumulation may also be factors
- Fisheries bycatch and incidental mortality
- Penguins and fisheries commonly target the same fish species
- Competition is difficult to monitor
- Another study (see publication for reference) showed how a penguin population in South Africa declined when sardine populations also fell
- Environmental variability and climate change
- Penguins appear to adapt in the short term, but if there are changes to their breeding this can change their abundance and distribution
- Direct evidence of climatic change and its effect on penguins is limited
- Toxic algal poisoning and disease
- Little is known about algal poisoning in penguins, there is one documented case which occurred in the Falklands
- There are possibly other unconfirmed instances
- Little is also known about disease outbreak, but there is the possibility that increases in tourism also brings with it the risk of pathogen introduction.
This study shows penguin decline is a complex issue with a number of potential factors. With protection penguin populations seem to be able to recover, but only once the threats are removed. This study concludes that this taxonomic group are at considerable risk, even though there has been a lower cumulative impact of human activities in the Southern Hemisphere.
For the full publication please see: Trathan, Phil N., et al. “Pollution, Habitat Loss, Fishing, and Climate Change as Critical Threats to Penguins.” Conservation Biology (2014).