An international team of researchers from Austria and the UK has shown that Goffin’s cockatoos (Cacatua goffiniana) can manufacture and use stick-type tools of appropriate shape and length out of three different materials, suggesting that the birds can anticipate how the tools will be used.
Tool manufacture was once regarded as a defining feature of mankind, but it is now known that a variety of animal species use and make their own tools.
In nature, some of the most striking cases of tool-related behavior are seen not just among our close relatives, chimps and other primates, but among birds including crows, vultures and Galapagos finches.
Goffin’s cockatoos, a species of Indonesian parrot which are known for their exploratory behavior, are a particularly interesting example for scientists to study. They do not build nests, nor are they known to be specialized for using foraging tools in the wild.
Research into the tool behavior of this species started after a captive male, called Figaro, spontaneously and reliably manufactured tools by cutting splinters out of larch wood, using them to rake in food placed behind the aviary grid.
In a set of ten observations, Figaro showed nine instances of tool making, one involving a different substrate (snipping of a branch from a leafless twig). As he took approximately four times as long to make his first tool as for any subsequent tool it is likely that we recorded his original innovation event.
In a follow-up study, three males were able to emulate Figaro’s tool use after receiving tool use demonstrations. Two later succeeded in making their own tools out of the same material (larch wood). One did so spontaneously and the other after one tool-making demonstration.
While impressive, these feats do not prove sensitivity to the need for the tools to be of a particular shape: because wood is fibrous, biting and pulling actions naturally split it into the long, narrow pieces necessary to succeed. If individuals are capable of anticipating the requirements of each tool, they should be able to produce functional instruments by displaying different actions and using different materials.
To test if Goffin’s cockatoos were in fact aiming to make elongated tools that could bridge a particular distance, the research team led by Dr. Alice Auersperg, of the University of Veterinary Medicine in Vienna, gave them the problem of reaching a piece of food placed a few inches beyond a circular hole in the transparent wall of a box.
The birds were given four different materials that required different manipulations to produce suitable tools: larch wood (already familiar to them), leafy beech twigs (which had to be trimmed to be functional), cardboard (which, lacking a fibrous structure, could be cut into any shape and length), and totally amorphous beeswax.
“While none of the birds succeeded in making tools out of beeswax, we found that at least some of them could make suitable tools from the three remaining materials,” Dr. Auersperg said.
The successful parrots made well-shaped tools, even though each material required different manipulation techniques.
To make tools out of larch wood, they bit the material once or twice and tore off the resulting splinter.
To use the leafy twigs, they snapped off redundant leaves and side branches until what was left was usable.
Finally, to make cardboard tools they simply cut what was necessary from the edge of the sheet provided.
“To us, the tools made from cardboard were the most interesting ones, as this material was not pre-structured and required the birds to shape their tools more actively,” Dr. Auersperg said.
“They succeeded by placing a large number of parallel bite marks along the edge of the material like a hole punch, using their curved upper beak to cut the elongated piece out of the cardboard block after reaching a certain length.”
“Interestingly, this length was usually just above or very close to the minimum length required to reach the food reward placed behind the barrier.”
“Ultimately, we want to understand how animals think — namely, to produce the equivalent of explicit computer programs capable of doing what the birds do,” added study senior author Prof. Alex Kacelnik, from the University of Oxford.
“We really don’t know if the birds can picture in their minds an object that doesn’t yet exist and follow this image as a template to build something new, or how their brains elicit the appropriate set of movements to organize their response to novel problems, but this is what we are trying to find out.”
The findings were published in the Nov. 2016 issue of the journal Biology Letters.
Alice M.I. Auersperg et al. 2016. Goffin’s cockatoos make the same tool type from different materials. Biol. Lett. 12 (11): 20160689; doi: 10.1098/rsbl.2016.0689