TWIL #062 - Crows Use Tools, Recognise Faces, and Hold Grudges for Years
Crows have the highest brain-to-body ratio of any bird and demonstrate problem-solving abilities that rival great apes - including tool manufacture, forward planning, and long-term memory of individual human faces.
- #animals
- #biology
- #nature
The crow family (Corvidae - crows, ravens, jays, jackdaws, magpies) contains some of the most cognitively sophisticated animals known. The common raven and New Caledonian crow in particular have demonstrated abilities long thought unique to great apes.
Tool manufacture: The New Caledonian crow (Corvus moneduloides) fashions tools from raw materials - bending wire into hooks, cutting leaves into specific shapes - to retrieve food from holes. This is not learned from humans; it has been documented in wild populations. In controlled experiments, crows have manufactured tools they have never seen before to solve novel problems, demonstrating causal reasoning about physical properties.
Multi-step planning: In experiments requiring crows to use a tool to retrieve a key, and then use the key to open a box to retrieve food, crows successfully plan several steps ahead - a capacity previously thought to require a neocortex, which birds lack. (Birds have a different but functionally analogous structure called the nidopallium caudolaterale.)
Face recognition and grudges: Research from the University of Washington (Dr. John Marzluff) demonstrated that American crows (Corvus brachyrhynchos) recognise individual human faces. In studies where researchers wearing specific masks trapped and banded crows, crows subsequently targeted those specific masked faces with alarm calls, mobbing behaviour, and dive-bombing - for years after the initial event. The behaviour spread to crows that had not been trapped but had learned the "dangerous face" from other crows.
Metacognition: Some corvid experiments suggest awareness of their own knowledge states - they will seek additional information before acting in tasks where they know they lack it, but not in tasks where they are certain. This is a form of metacognition.
Funerals: When a crow dies, other crows gather around the body, calling loudly. Research suggests this serves a learning function - the crows are associating the location and any nearby humans with danger, not mourning in an emotional sense.