The Huia was a type of wattlebird that lived exclusively on the North Island of New Zealand. It was known for the strikingly different beak shapes between the males and females, and for it's orange cheek colouring.
The difference in beak shapes between the male and female huia is the greatest in all known bird species:
Male beak: short and wide. It was most useful for breaking away at wood to get insects.
Female beak: long, thin, and curved downward. It was most useful for eating larvae out of deeper crevices than the male.
This difference is likely so that the one species is able to utilise two different food sources. Usually another species would be able to more effectively focus on another food source, outcompeting the huia. Luckily for the huia however, their island habitat had little competition.
The huia lived in the dense native forests throughout the North island.
The huia was originally widespread throughout the island. When the Maori arrived, they hunted it for its feathers. The Maori did not drive it to extinction, but it was already limited to the south end of the island by the time European settlers arrived.
Once the European settlers arrived, the species declined more rapidly. The feather became a fashion symbol for many in England, and feathers sold for a high price. This made them an attractive option for hunters.
Another factor was the introduction of invasive species to the island. Cats would have found the huia easy prey, particularly as they often fed on or near the ground.
Despite being apparently "plentiful" in some areas in the early 20th Century, they were completely extinct just a few years later.