https://arstechnica.com/science/2017/07/ravens-ignore-a-treat-in-favor-of-a-useful-tool-for-the-future/

Hard to overstate the importance of this single statement:

“Perhaps most importantly, four out of five ravens got these tasks right »on the first trial», before they had any chance of learning the particular task by experience or building habits. They also aced the tasks when the waiting period was extended to overnight.”