Direct human impacts
Many of the threats to penguins like oil spills and the presence of introduced predators have indirect effects on penguins, however humans can have direct impacts too.
In the past both penguins and their eggs have been harvested for food by indigenous cultures. This practice is now probably limited to South America where fishermen take penguins for food and for fishing bait. The harvest of bird droppings, including those of penguins, from seabird islands to use as agricultural fertilizer was a common practice in the 19th and early 20th century. The harvest directly disturbed nesting penguins but also had the impact of removing much of the material in which the penguins burrowed to nest.
Disturbance of penguins by tourists attempting to view them is a growing problem. Susceptibility of penguins to disturbance varies between species. Some evidence of reduced breeding success and lower chick fledge weights has been seen in yellow-eyed penguins viewed by unsupervised tourists. Conversely blue penguins in a controlled tourism situation show no adverse impacts.
The continuing trend of coastal subdivision and housing development places pressure on some penguin species, in particular blue penguins. While blue penguins can survive in urban environments and may receive some protection from mustelid predators, dogs usually increase in number and if penguins have to cross roads to reach their nesting site then cars are a significant threat.