These hypotheses are difficult to tease apart in a tool use task as it would require translocating wild birds to different areas and examining the impact on their tool using behavior. An alternative solution is to investigate how the acquisition of a novel behavior (accessing food in different ways from an apparatus) spreads through a group. This would reveal whether New Caledonian crows are capable of the complex social learning which would be required for cultural transmission of tool use behaviour.
A recent paper
published in the Psychonomic Society’s journal Learning and Behavior
from researchers at the universities of Cambridge, St Andrews, Auckland and Anglia Ruskin has tested exactly that. Researcher Corina Logan presented three groups of crows with apparatuses containing a food reward. Each apparatus could be accessed in four different ways at three different locations.
Two demonstrator birds (one from each experimental group) were trained to access food at a specific location and in a specific way; this was different for each bird. Two versions of the apparatus were then put into the aviary and all birds within the group could access the food. The design allowed the researchers to investigate what the birds were learning from observing the demonstration. Did they simply learn about the specific place that the demonstrator was getting access to the food, or did they learn about how the demonstrator was getting food, the specific actions required to access it? The third group, a control group, simply got access to the apparatuses and the researchers monitored how they would naturally access the food without seeing a demonstration from another individual. The apparatuses were placed in the aviary with all the group present so that the spread of the behaviours throughout the groups could be observed.
The results revealed that the birds socially learned about the position that a bird was using to access food, but they did not learn about the action that the demonstrator was performing.
The results thus did not demonstrate the sophisticated social learning skills, such as imitation, which are likely to result in the social transmission of knowledge about tool making. Rather, the birds went to the area where another bird had been foraging, the authors suggest that this sort of local or positional enhancement may influence the birds foraging behavior. Thus, they may be attracted to a specific area because of the presence of the other birds and then learn individually about the local ecology: It is therefore possible that the birds learn about tool types from observing discarded tools which are in the area.