Dr. George Murray Levick was a member of the ill-fated Scott expedition to the South Pole in 1910 where he observed penguin behavior, including necrophilia, that so shocked him that he recorded his observations in Greek so that others would not be able to read about them accidentally.
He later tried to publish his observations in a paper but felt that those sections were too much for those times and were omitted. The full paper was found recently by Douglas Russell, curator of eggs and nests at the Natural History Museum, who said:
“I just happened to be going through the file on George Murray Levick when I shifted some papers and found underneath them this extraordinary paper which was headed ‘the sexual habits of the adelie penguin, not for publication’ in large black type.
“It’s just full of accounts of sexual coercion, sexual and physical abuse of chicks, non-procreative sex, and finishes with an account of what he considers homosexual behaviour, and it was fascinating.”
In short, penguins seem to exhibit the same range of sexual behaviors as humans.