Penguin

Frobisher morphs back into a Penguin. (DWM: Where Nobody Knows Your Name)

Penguins were birds that lived in cold or wet places. They mostly gathered in polar regions. Frobisher took on the form of a penguin as his wife Francine had been fond of them. He occasionaly changed between variations of the species. (DWM: Voyager)

Penguins mated for life and often appeared on greetings cards. (TW: Something Borrowed)

Antarctica was often associated to penguins due to their presence on the continent. (EDA: EarthWorld)

In 1970s London, the Third Doctor and the Brigadier encountered penguins at a zoo. They had dived into their pool to escape a flock of parrots which were attacking them, but the penguins attacked them as well. (TVC: The Arkwood Experiments)

In an alternate timeline, penguins lived on the River Nile in Egypt. (DW: The Big Bang)