This crow broke her beak 8 years ago in a collision with a car. Her couple of 12 years has patiently fed her since.

CROWS UNDERSTAND A THING OR TWO ABOUT IMPULSE CONTROL.
A 2014 study shows that at least some corvids can resist the urge for instant gratification—if you make it worth their while. The research was led by University of Göttingen graduate student Friederike Hillemann, whose team assembled five common ravens and seven carrion crows. Through careful note-taking, the scientists figured out what the favorite meal items of all 12 animals were. Then the experiment began.