New Caledonian Crows Evolution

A second study was conducted on another African – grey parrot named Alex, in this study the parrot was taught to use English vocalizations to identify, demand or decline or simply comment upon over a range of 80 different objects. These objects were of a variety of colours, shapes and materials (Pepperberg 1987). The bird revealed a fundamental ability of categorization (Pepperberg 1983), and can identify quantity for groups of up to 6 objects. Alex also gained functional use of phrases such as “come here”, “no”, “I want X” and “wanna go Y” where X and Y were appropriate objects or locations (Pepperberg 1987). As this study offered the parrot a wider variety of different objects to choose from with different criteria applying to the objects

This study demonstrated evidence that New Caledonian crows, Corvus moneduloides have diversified and cumulatively changed the design of their pandanus tools for the purpose of extracting prey from vegetation in the rainforest (Hunt 2000). New Caledonian crows were offered a selection of sticks of varying lengths and a tube containing food. The crows chose a tool of either the appropriate or greater length. In a second task, the food was positioned behind a small opening, this time the crows chose a tool narrow enough to pass through the hole and push the food out. If the crows chose a tool that was too wide, they often modified the tool to make it fit (Emery and Clayton 2009). This alteration of the tools suggests size judgement and possibly insight in the mind of the crow, it can recognise that the first tool is too wide and will need to be made smaller in order to complete the task and acquire the food. Judgement is one of the criteria for cognition so it could be suggested this study shows cognition in the New Caledonian crows. While several birds can learn to select and pull up the correct string which is attached to the food when more than one string is presented (Ducker and Rensch 1977) it is only keas and hand-raised ravens (Corvus corax) that have been proven to solve novel problems of string-pulling, such as crossing the strings, altering the string’s colour or attaching one string to a stone to eliminate the possibility of the weight giving away the correct string. Both species of bird were able to select the correct string on the first attempt and then continued to complete the tasks at a high performance level (Heinrich 1995). This results of this study are debatable in proving that these birds are showing aspects of insight, however, it is certainly demonstrating rapid