There are two species of Chimpanzees, both of which are the closest living relatives to humans. Chimpanzees make tools and use them to acquire foods and for social displays; they have sophisticated hunting strategies requiring cooperation, influence and rank; they are status conscious, manipulative and capable of deception; they can learn to use symbols and understand aspects of human language including some relational syntax, concepts of number and numerical sequence; and they are capable of spontaneous planning for a future state or event.
Elephants exhibit mirror self-recognition, an indication of self-awareness and cognition. Elephants are known to use tools, but not as advanced as that by chimpanzees. They are popularly thought of as having an excellent memory. Elephants appear to have some ritual around death and show a keen interest in the bones of their own kind.
Several researchers rank dolphins at about the level of elephants in “intelligence”. They are known to engage in complex play behavior and have great communication skills. Dolphins have been recently observed using tools in a basic matter: when searching for food on the sea floor, many dolphins were seen tearing off pieces of sponge and wrapping them around their “bottlenose” to prevent abrasions.
Parrots are able to mimic human speech, but the African Grey Parrots are able to associate words with their meanings and form simple sentences. Some species of parrot such as the Kea are also highly skilled at using tools and solving puzzles.
Sheep can recognize individual human faces, and remember them for years. In addition to long-term facial recognition of individuals, sheep can also differentiate emotional states through facial characteristics. If worked with patiently, sheep may learn their names.It has been reported that some sheep have apparently shown problem-solving abilities.
Rats show excellent problem solving skills. They have also been found to be actively prosocial. They demonstrate altruistic behaviour to other rats in experiments, including freeing them from cages. When presented with readily available chocolate chips, test subjects would first free the caged rat, and then share the food.
Dogs are pack animals by nature and can understand social structure and obligations, and are capable of interacting with other members of the pack. They are known to be highly intelligent and very easy to train by humans.
The Octopus is considered the most intelligent invertebrates. They show impressive spatial learning capacity, navigational abilities, and predatory techniques. It has also been claimed, but strongly disputed, that octopuses practice observational learning.
Wild hooded crows in Israel have learned to use bread crumbs for bait-fishing. Some Crows have been found to engage in feats such as sports, tool use, the ability to hide and store food across seasons and episodic-like memory. The New Caledonian Crow show ability to manufacture and use its own tools in the day-to-day search for food. Crows in Australia have learned how to eat the toxic cane toad by flipping the cane toad on its back and access the non-toxic innards; Crows have demonstrated the ability to distinguish individual humans by recognizing facial features.
Pigeons can be taught relatively complex actions and response sequences and can learn to make responses in different sequences. Pigeons can also remember large numbers of individual images for a long time, e.g. hundreds of images for periods of several years.