South Bird

The South Bird (サウスバード) is a type of bird found in Jaya and Skypiea. These strange looking birds have an odd habit of always pointing their head south, no matter where they are (much to the amusement of Luffy). In fact, they find it most uncomfortable to point in any other direction. Because of this, they were used in ancient times to navigate. They have a very strange call (choooooo) that can control bugs.

Jaya
On Jaya the Straw Hats needed a South Bird to find there way to the Knock-Up Stream. Montblanc Cricket told them they needed a South Bird to act like a compass so they could navigate to the Knock-Up Stream. Nico Robin eventually caught the bird and held him for the trip to Skypiea. The South Bird escaped once the crew made it to Skypiea. In a comedic twist, the South Bird came back to the Going Merry. Chopper translated for the bird, stating that he did not want to stay at Skypiea. After Chapter 302, the South Bird is not seen again. In the anime, the South Bird's role was somewhat extended to play another comedic role as he annoys Vice Admiral Johnathan in the G-8 Arc. The South Bird was again unseen after that. This variety first appeared in Chapter 230 and Episode 149.

Skypiea
The South Birds in Skypeia are much larger then those found in Jaya and seemingly much friendlier. Chopper, Gan Fall, and Pierre were saved from drowning by them after their encounter with Shura. Chopper learns from them that Gan Fall was the previous God of Skypiea. Later, one saved Zoro's life only so it could steal his lunch. It also laughed at Zoro for getting lost (prompting Zoro to throw his backpack at it). Despite its friendly nature, it's not above sacrificing something at hand to save its own skin (such as when it dropped Zoro so the Giant Python would leave it alone). This variety first appeared in Chapter 251 and Episode 164.

Trivia

 * Ironically, a South Bird started following Zoro, who was lost at the time and needed to go south, but was going in the opposite direction as indicated by the South Bird's head pointing the other way.