Wild crows were captured by researchers who were wearing masks, which the scientists referred to as the ‘threatening face’. This created a negative association with that particular mask. Then, for the four weeks the crows were held in captivity, they were fed by people wearing a different mask – the ‘caring face’.
At the end of the four weeks, the crows were injected with a harmless glucose fluid before being presented with someone wearing one of the two masks. Then, after 15 minutes of exposure, the birds were sedated and scanned. The glucose fluid had flooded to the areas of the brain that were most active, providing a snapshot of the crows’ brain function.
“In our experiments and in nature, when perceiving a threatening face, crows froze and fixed their gaze,” say the researchers. “[This] was associated with activation of brain regions known in birds to regulate perception, attention, fear, and escape behavior.” One of the regions activated by the threatening faces was the crows’ equivalent of the amygdala, an area of the human brain in which negative associations are stored as memories.
This is the first time a study of this kind has been performed on wild animals, and it could have promising applications. Ecologists hope to protect rare species like the snowy plover bird by giving their natural predators – crows and ravens – negative associations with eating them. Due to a crow’s ability to learn quickly and store information long-term, training the birds to “do the right thing” and avoid threatened prey could well be possible.