On a day in every year, called Shraddha feast befitting the sanctity of the abode of the ancestors is afforded. Crows are omnivores, who are fed by one and all during shraddhas. This is not because of one particular reason, but there are many reasons.
The major reason why crows are fed in the Shraddhas is that it is believed that our ancestors come down in the form of crows. Therefore, if we feed crows, we are basically feeding our ancestors. Thus, sometimes it is even noted that people cook the favorite food of the ancestors, in order to please them through feeding that same food to the crows.
Crows only are fed and not any other birds, because they recognize the individual human face and can even mimic human voices. This being social of the crows, gives us a feeling of care just like it was with our ancestors.
Since crows are associated to the cycle of life and death as per our Hindu Mythology, therefore once the crow feeds on the food that is put to them, we assume that our food has reached our ancestors and they have showered all their blessings on us.
Crows are man’s good companions and have always been found staying with the man since time immemorial. Thus, by feeding crows, one actually does good to others and even to oneself by doing some gesture of kindness.