Using tool kits and transporting them to the job site has long been considered a skill reserved for humans and chimpanzees. A new study shows that Goffin’s cockatoos can do it too. In the experiment, the birds brought two different tools to their feeding station in order to get a cashew nut hidden in a locked box. This suggests that they actually perceive the tools as a set and are aware that both are needed to complete the task.
Few animals are able to combine tools to get to hard-to-reach food sources. So far, this has been best researched in chimpanzees. Observations have shown that some wild chimpanzees use two different types of sticks to break up termite mounds and scoop out the termites. For a long time, however, it was unclear whether the monkeys only recognized the need to reach for a longer, flexible fishing rod when they saw the mound broken up with the first tool, or whether they knew from the start that they would need both tools. Only the observation that some of the chimpanzees actually deliberately transport both tools to the termite mound made it clear that our closest relatives actually perceive their tools as a set.
Cockatoos as tool artists
Inspired by chimpanzees, a team led by Antonio Osuna-Mascaró from the University of Veterinary Medicine, Vienna, developed a similar experiment for Goffin’s cockatoos. The small white parrots are originally from the Indonesian Tanimbar Islands between the Asian and Australian mainland. A group of Goffin’s cockatoos lives at the University of Veterinary Medicine in Vienna and has demonstrated in numerous previous experiments that the birds can make, use and store tools.
For the current study, the researchers gave ten of their protégés a previously unknown task: “First, we wanted to test whether they were able to develop the use of a tool set themselves,” says Osuna-Mascaró. “So we gave them a problem similar to that of chimpanzees catching termites. We blocked the birds’ access to a cashew nut lying in a box with foil and provided them with two tools: a short, pointed stick and a long, flexible plastic straw. The foil could only be torn open with the pointed tool, which was then too short to reach the reward. So both had to be used one after the other.”
Flexible usage
For the first experiment, the box was placed where it was easily accessible so that the birds could learn about the task. The research team planned ten minutes for the solution. But the birds amazed the researchers with their speed: Two of the cockatoos made it on the first try in less than 35 seconds. Five other cockatoos also got the hang of it after two or three attempts.
For the further experiments, the team varied the experimental setup slightly. “To test whether the cockatoos were flexible in using their tool set, we randomly presented them with two different boxes in turn: one covered with foil, as before, and another without foil,” Osuna-Mascaró explains. “So the cockatoos had to act depending on the problem: sometimes the whole tool set was needed, sometimes a single tool was enough.” This is reminiscent of the situation of chimpanzees when catching termites: sometimes the whole tool set is necessary; for termite mounds that already have holes, the fishing rod is sufficient. In this experiment, too, the Goffin cockatoos quickly found out when they needed which tool.
Planned combination
But is the use of the tools a sequence of independent actions, or do the birds actually perceive the tools as a set? To find out, Osuna-Mascaró and his team placed the box – with or without foil – in a more difficult-to-reach place. Sometimes the birds had to climb a ladder, sometimes they had to fly horizontally or vertically to get to the platform with the box. Like the chimpanzees, would they take both of the tools they might need with them so they wouldn’t have to make the strenuous journey again?
In fact, several individuals chose to take both tools with them at the same time. If they could see from a distance that the box was sealed with foil, they always took the complete set with them. On the other hand, if the opening of the box was open, they decided to do so less often. “Our cockatoos always had the option to fly back and forth, use one tool, and then come back to pick up the other tool, carry it to the feeding station and use it there,” explains Osuna-Mascaró. “Instead, at least three of them learned to take both tools with them in advance. This suggests they can categorize both tools as one set.”
Learned rather than innate
The results show that not only humans and chimpanzees, but also the evolutionarily distant Goffin cockatoos are able to perceive and use tool sets as such. In birds, such abilities were previously only known from New Caledonian crows. However, since they also regularly use tools in the wild, it can be assumed that this behavior is innate in them. In contrast, no tool use has been observed in free-living Goffin cockatoos. The researchers therefore assume that this is a learned behaviour.
Source: Antonio Osuna-Mascaró (University of Veterinary Medicine, Vienna, Austria) et al., Current Biology, doi: 10.1016/j.cub.2023.01.023