{"fact":"Crows can quickly adapt to new rules about when to call or stay silent, showing a surprising level of mental flexibility.","context":"Both crow E and Y learned the new task quickly. It took them 3 days (548 and 626 trials, respectively) to learn that the previous go cue was now indicating the waiting period, and vice versa.","source":"Katharina F. Brecht; Steffen R. Hage; Natalja Gavrilov; Andreas Nieder, Volitional control of vocalizations in corvid songbirds, 10.1371/journal.pbio.3000375","index":209}