As usual when I ponder over the words used to describe deities they are like unlocking a code. The wise men (writers of vedas and other texts) have found a foolproof way to pass on the wisdom to generations. They have used sanskrit language in such a way that each mythological person or creature has a deeper meaning only if you care to double click.
Now about saras. The sacred bird, if offered a mixture of milk and water, is said to be able to drink the milk alone. What does it signify- the power of discretion. Ability to pick the good from bad....