New Discovery – Jungle crows can identify symbols

Japanese researchers from Utsunomiya University have discovered that crows possess the ability to distinguish between symbols representing different quantities. This works down to the fact that crows have the same numerical cognition ability as humans.

 The birds successfully selected containers containing the highest quantity of food by identifying numbers marked on the lid. The crows were able to pick the correct box 70 percent of the time

When crows could discriminate five items (15 out of 20 correct choices in two blocks of 10 trials each), they received control tests for non-numerical cues such as element configuration, shape, and total filled area and novel quantity (3 versus 5, 4 versus 5, 5 versus 6, 5 versus 7 and 5 versus 8) tests. During training, jungle crows learned the discrimination task relatively quickly.

The crows were responding to quantity. The researchers say Jungle crows selected the familiar larger quantity in smaller sets (3 versus 5 and 4 versus 5) and the novel larger in larger comparisons (5 versus 7 and 5 versus 8) except that of 5 versus 6 quantities.

The researchers say the results suggest that jungle crows have a natural tendency to select the larger quantities and that decisions were affected by the numerical ratio and stimuli magnitude, indicating the use of analogue magnitude mechanism for numerical judgment, as is observed in other animals.

Journal reference 

Quantity discrimination in jungle crows, Corvus macrorhynchos 
Animal behaviour,  Pages 635-64, Volume 82, Issue 4 (October 2011)
Bezawork Afework Bogale, Naoki Kamata, Katano Mioko, Shoei Sugita