New Caledonian crows, otherwise known as the Corvus moneduloides, have bills that are very stout, blunt, and straight. They are also one of a few species that use and make tools year round and throughout their whole territory. Based on a Scientific Reports study, their bills became specialized over time for controlling stick tools, which help them pull grubs out of tight spaces.
In people, specific adaptations have improved our capability to control tools. This kind of adaptive specialization could also have evolved in New Caledonian crows. They make use of the end of a tool – sticks, bristly leaves, or twigs that are aquiline – to irritate longhorn beetle grubs by poking around their face, hiding in tree trunks. The smart crow places the point of the tool in the jaws, able to take out the grub when it bites down when a grub responds.
Using CT scan and shape analyses, a team headed by University of Auckland’s Gavin Hunt and Ei-Ichi Izawa of Keio University analyzed the shape and inner arrangement of the New Caledonian crow’s bill.
The lower mandible really arch somewhat upward, which probably gives it the strength it must hold the tool,” study coauthor Kevin McGowan of Cornell said in a statement.
The bill became specialized for managing them after the crows started using tools. These behaviours probably evolved over a lengthy time period, but remains unknown just why the crows began using tools. In the end, most fowl snatch quarry just great using their beaks and feet. Toolmaking among crows could have occurred by chance, and tool use become ingrained within their biology.