{"fact":"The difficulty a jungle crow has distinguishing between quantities increases as the numerical ratio between the sets gets smaller (e.g., 5 vs. 6 is harder than 5 vs. 8).","context":"...and that decisions were affected by the numerical ratio and stimuli magnitude, indicating the use of analogue magnitude mechanism for numerical judgement, as is observed in other animals.","source":"Bezawork Afework Bogale; Naoki Kamata; Katano Mioko; Shoei Sugita, Quantity discrimination in jungle crows, Corvus macrorhynchos\n, 10.1016/j.anbehav.2011.05.025","index":238}