The death of four baby blue penguins from nothing but "human stupidity" has broken the heart of Mauao Area Wildlife Trust chairwoman Julia Graham.
Mrs Graham monitors the penguins on Moturiki (Leisure) Island but has noticed an alarming increase of people drinking on the liquor-free island late at night and trashing the environment.
Two young penguins were trapped and starved to death because empty beer bottles were shoved into the entrance of their burrow, she said.
"The burrow was completely blocked off so the parents couldn't get to their babies to feed them."
Another two healthy eggs were abandoned by their parents after increasing activity around their burrow.