Could tagging penguins hurt them?
Attaching tags to penguins' flippers makes them easier for scientists to spot - but it may also harm the birds, according to new research.
Scientists studied king penguins for 10 years and found those with flipper tags died younger and had fewer babies.
It means research done using tagged penguins could be invalid - as the tags change the way the birds behave.
That's a big deal because king penguin research is sometimes used to make predictions about climate change.
And if the tags change how long the birds live, then predictions about the affect of climate change on them could be inaccurate.
Flipper tags make penguins much easier to spot
A team of French scientists studied 100 king penguins for 10 years on Possession Island off the Antarctic coast.
Half the penguins wore flipper bands, the other half had electronic tags under their skin.
Scientists found the penguins with flipper bands tended to die younger and have fewer chicks.