6. In some places, such as islands in the southern Indian Ocean, fishermen still use penguin meat for bait.
7. Human competition for food sources can affect penguin populations. Overfishing of anchovetta (a small fish), the primary food source of the Humboldt penguin, has contributed to their population decline.
8. The introduction of predators has had devastating effects in some areas. Rats, dogs, pigs, and ferrets have been known to prey on chicks, eggs, and even adult penguins. Introduced herbivores, such as sheep and rabbits, cause serious deterioration of habitat.
9. Colonies of penguins have been affected by building activities and road construction. One colony of king penguins at Iles Crozet (a small group of islands in the Indian Ocean) was completely destroyed. A nearby area was cleared, and fortunately, the penguins recolonized.
10. Trash in the ocean can affect seabirds. Penguins have been known to ingest plastic or become tangled in debris, causing injury and death.
11. Oil spills affect penguins.
a. Oil fouls their feathers, reducing the waterproofing and insulating properties of their plumage. The birds become susceptible to hypothermia (chilling).
b. Penguins also ingest the oil while trying to preen, poisoning them and causing internal organ damage. c. Oil spills are a continued threat. In June 1994, an estimated 40,000 African penguins were affected by an oil spill off South Africa's Cape peninsula. More than 2,400 tons of fuel oil was spilled. The disaster occurred during the penguins' breeding season, affecting the survival of chicks and unhatched eggs. The long-term success of emergency clean-up efforts probably will not be determined for several years.
12. Traces of dichlorodiphenyltrichloroethane (DDT) and other pesticides (chlorinated hydrocarbons) have been found in the tissues of Adélie and chinstrap penguins. Scientists speculate that these pollutants were transported by ocean currents or other animals. Their appearance in antarctic penguins is significant in that these toxic substances have now reached the pristine Antarctic.
Enthusiastic sightseers must be careful not to interfere with normal penguin activity.
13. Activity that may seem harmless, such as aircraft flying over penguin colonies, may cause panic and stampedes, resulting in injuries and easy predation.
14. The popularity of "ecotourism" is increasing with cruise ships frequenting antarctic waters. Enthusiastic sightseers must be careful not to interfere with normal penguin activity by staying back and keeping noise levels down.
15. Penguins may be indirectly affected by past hunting of whales. The increase of some penguin species over the last 30 years may be attributed to the greater availability of krill following the reduction of some antarctic whale populations. However, the commercial value of krill may encourage large-scale harvesting of this resource in south polar waters, which would impact penguins and other marine animals that rely upon krill as a food source.
