The World Conservation Union, which lists the African penguin as "vulnerable," notes, however, that potential global warming in the future could cause more nest desertions and less reproductive success.
Conservationists say other threats, including oil pollution and a dwindling food supply, are the major factors behind the penguins' vulnerable status today.
- Emperor Penguins: Uniquely Armed for Antarctica
- "Penguin Ranch" Reveals Hunting, Swimming Secrets
- Patagonia Penguins Make a Comeback
- Penguin Decline in Antarctica Linked with Climate Change
- Ice Buildup Hampers Penguin Breeding in Antarctica
- Tagging Hobbles Penguins, Some Researchers in Cape Town Contend
The guano harvests of the mid 1800s were among the first intrusions of humans into the jackass penguin world. Most of the islands off South Africa were scraped clean of bird dung by the start of the 20th century. But humans continued to have a devastating impact on the birds.
"Probably the main cause of decrease in the early 1900s was harvesting of penguin eggs," Crawford said. The South African government marine conservationist estimates the total African penguin population at the time was around 1.5 million.
In the first half of the 20th century, 48 percent of the eggs produced on South Africa's Dassen Island (one of the penguin's main nesting sites) were harvested, according to data supplied by the World Conservation Union and the field guide Robert's Birds of Southern Africa. The practice was outlawed in 1967.
In more recent decades, the penguins have been harmed by increased oil pollution. Oil reduces the insulating properties of the penguins' feathers. Many affected birds die from hypothermia as a result.
The problem has been fueled by accidental tanker spills as well as intentional bilge cleaning by ships rounding the Cape of Good Hope on their way to the Persian Gulf.
Other threats to the penguins include competition with cape fur seals for overfished stocks of anchovy and sardines. The seals also displace the penguins from breeding sites and, together with great white sharks, prey on the penguins.
"I would rate food limitation as the most important present cause of the unfavorable conservation status, followed by oil spills and adverse interactions with seals," Crawford said.
According to the World Conservation Union, a minimum viable population of about 50,000 nesting pairs is required to give the African penguins a less than 10 percent risk of extinction, which is about where the population stands today.
To help the penguins on the road to recovery, most of their nesting islands are protected. Recently established mainland colonies are also fenced off to prevent predation. Conservationists provide the birds with nest boxes to shield them from the elements.
Organizations like the Southern African Foundation for the Conservation of Coastal Birds, meanwhile, are meeting with success in their efforts to clean, rehabilitate, and release back into the wild penguins that become coated with oil.
Crawford hopes that conservation efforts will result in a population rebound to at least a hundred thousand nesting pairs, a number sufficient to reduce the risk of extinction in the wild to about 5 percent.
For more penguin news, scroll down.
SOURCES AND RELATED WEB SITES