Crows are fascinating birds and among the smartest animals in the world. A new study demonstrates how effectively crows can reason cause and effect.
We know that corvids are capable of using tools, recognising humans and passing knowledge on to their families — but a collaborative study between the University of Cambridge, the University of Auckland and the University of Vienna has shown us how crows are also capable of understanding cause and effect.
The study, New Caledonian crows respond to hidden causal agents, tested eight wild crows in two different scenarios. In both, the crow was placed in an environment where a stick would emerge from a wall. In the first scenario, a human would enter the enclosure at the same time the stick moved, so that the crow would associate the stick's movement with the human's presence. When the human departed, the crow would relax and go about the business of obtaining hidden food using a twig.
In the second scenario, the stick would move out of the wall without a human presence in the enclosure. With no third party with which the crow could associate the stick's movement, the crow was much more nervous and wary, taking its time to extract the food, just in case the stick moved again.
The study is explained in more detail here:
Not convinced? Take a look at the David Attenborough video below, where a crow drops a nut into traffic and onto a pedestrian crossing so a car can drive over it, then waits for the lights to change before swooping in to safely grab its prize.
Bonus fun fact: in February 1533, the parliament of Henry VIII passed an act allowing the destruction of choughs, rooks and crows. Previously, the birds had been protected under the law because of the "janitorial services they performed on city streets".