Complex cognitive capacities exist in a wider range of animal
species than scientists once thought possible.  A Grey Parrot
(<italic>Psittacus erithacus</italic>), Alex, has learned to
comprehend and use English labels to identify numerous objects, seven
different colors, five different shapes, and various materials (e.g.,
paper, wood, hide, cork).  He combines all his vocal labels to
identify proficiently, request, refuse, categorize, and quantify more
than 100 different objects, including those that vary somewhat from
training exemplars.  He understands concepts of same/different,
bigger/smaller, absence of information, and appropriate use of certain
human phrases such as "come here", "I want X" and "Wanna go Y" (where
X and Y are appropriate labels for objects or locations).  His
achievements are being replicated by younger parrots, who are also
involved in studies to examine the effectiveness of various training
techniques.  Alex's abilities were once thought to be limited to
humans, or at least nonhuman primates.