The bands that scientists attach to penguins to track them actually do harm. The data also suggests that certain climate research might also be skewed because of this. Key quote:
Overall, the team found, bands were bad for penguins. Banded penguins had a 16% lower survival rate than unbanded birds over the 10 years, the researchers report online today in Nature. Banded birds also arrived later at the breeding grounds and took longer trips to forage for food. As a result, they produced 39% fewer chicks. . . . [The researcher noted] that his team’s results suggest that research using banded penguins may be biased. For example, he says, several high-profile studies have used banded penguins to investigate the impact of climate change on the birds. The findings of those studies aren’t necessarily wrong, but the numbers need to be reconsidered, he says.