The difficulty of defining or measuring intelligence in non-human animals makes the subject difficult to study scientifically in birds. In general, birds have relatively large brains compared to their head size. Furthermore, bird brains have two-to-four times the neuron packing density of mammal brains, for higher overall efficiency. The visual and auditory senses are well developed in most species, though the tactile and olfactory senses are well realized only in a few groups. Birds communicate using visual signals as well as through the use of calls and song. The testing of intelligence in birds is therefore usually based on studying responses to sensory stimuli.

The kea is a species of large parrot in the family Nestoridae found in the forested and alpine regions of the South Island of New Zealand. About 48 cm (19 in) long, it is mostly olive-green, with brilliant orange under its wings and has a large, narrow, curved, grey-brown upper beak. Its omnivorous diet consists mainly of roots, leaves, berries, nectar, and insects, but also includes carrion. It was once killed for bounty due to concern by sheep-farmers that it attacked livestock, especially sheep. The kea is now uncommon, and received absolute protection under the Wildlife Act in 1986.