When you were reborn as wild animals, your mothers treated you with loving kindness and looked after you. When your mother was a bird, for example, she shielded you with her wings for nearly a month.  And if enemies threatened, such as a man with a stick, she would protect her precious chick with her life although she herself could have flown away.  Later, she would feed you and even if she only managed to find a single worm, she would give it to you. Therefore, sentient beings have not been kind to you just once or twice: they have shown you kindness in every type of situation.  Their kindness is beyond reckoning.

-- Pabongka Rinpoche