Men wish either to kill birds for food or to keep them in cages for sport. There is no third reason except killing or caging for which men would seek birds.
भक्ष्यार्थं क्रीडनार्थं च नरा वाञ्छन्ति पक्षिणः। तृतीयो नास्ति संयोगो वधबन्धादृते क्षमः॥