Children learning about ,Where do Birds go & What do they eat in Winter?

Children are very interested in finding out what do birds eat? when it is very cold and there is no food outside. we all went out side and while listening for sounds, we did not notice much sound of birds. One of the child mentioned ,they are sleeping in their nests, other one said they are gone hybernation, third suggested no no they migrated---- . but then we saw a crow and a bird. So we decided to find out the answer when there is lot of snow and it is very cold what do birds eat etc.
I  encourage little ones to explore and with my help on laptop find out the answers ---- Research! this is our new word.