God has bestowed conscience— discriminating power between good and bad, eternal and non-eternal to human beings. So they can accept that which is eternal and good and give up that which is non-eternal and bad. Human beings, because of their power of discrimination, are superior to all other species of living beings.
As human beings have got this discriminating power between good and bad, right and wrong, if they do wrong and bad actions, they are liable to be punished, as stated in the Gita— `Karmani evadhikaras te ma phalesu kadacana’— `You have got right to do karma— actions, but fruits of actions are controlled by Me (Supreme Lord Sri Krishna).’ As beasts, birds etc. have got no such discriminating power and as they are insensible— without the sense of understanding, they are not punished like human beings. They have got their development in gradual procedure. There are exceptional cases in regard to this as stated in the scripture— `A pigeon being shot by a hunter with an arrow, fell down on the ground from a tree, circumambulated Vishnu temple while fidgeting and died. Due to this eternal good deed, not knowing that God is satisfied if any living being circumambulates His temple that living being will get the approved fruit, the pigeon got next birth human body in a Brahmin family, crossing over numerous intermediate other births, got association of bona fide devotee and attained the Lotus Feet of Supreme Lord.
— Srila Bhakti Ballabh Tirtha Goswami Maharaj