Sri Rama and squirrel.. where did this story originate?

Question

There is a famous story about a squirrel helping Sri Rama in building the bridge (Rama setu) to go to Lanka.

A squirrel sees Vanara army accumulating boulders and rocks for the bridge. A squirrel decides to help Sri Rama and picks up sand and pebbles. Sri Rama notices it and appreciates the effort of the squirrel and warmly stroked the back of the squirrel with his fingers. Since then, it is believed that squirrels have three lines on their body.

The moral of the story is to recognise and appreciate the help even when it comes from a small person.

This story is not a part of Ramayana written by Valmiki and Ramcharit Manas written by Goswami Tulsidas. These aren't the only versions of Ramayana. There are many other versions by many poets.

Question:

What is the origin of this story involving Sri Rama and squirrel?

From which later versions of Ramayana did this story originate?

Related question: Why do only Indian squirrels have stripes on them?

Answer 1

Page 139 of this book says that the first version of the Ramayana that contains the squirrel story is the Ranganatha Ramayanam, the 14th century Telugu version of the Ramayana:

There are many innovations in this Ramayana.... It narrates [a] moving incident of a squirrel who helped Rama to construct a bridge on the sea. Not necessarily [wwre these] inventions by the poet himself; they could have been appropriated from folk sources[.]

Page 107 of this book says the same thing.

But the story seems to be considerably older than the 14th century, because one of the Alwars, Thondaradippodi Alwar, alludes to it in one of his poems:

pOdellAm pOdu koNDu un ponnaDi punaiya mATTEn
teedilA mozhihaL koNDu un tiruguNam Seppa mATTEn |
kAdalAl nenjam anbu kalandilEn adu tannAlE
EdilEn arangarkku ellE en SeivAn tOnrinEnE ||

Nor am I like the humble squirrel which rolled in the sand and helped, when the monkeys pushed big rocks to build a bridge in the ocean. With a heart full of vice, a heart as hard as wood, infamously I labor, without a single service to the Arangam Lord.

Even by modern dating, Thondaradippodi Alwar dates at least to the 8th century.

Answer 2

So far, I've found the squirrel's story in the Hindi translation of Ranganātha Rāmāyaṇa (RR) and Kṛttivāsa Rāmāyaṇa. However, I couldn't locate this story in the original, Telugu version, of RR.

This, from the Hindi tr. of RR:

From Kṛttivāsa Rāmāyaṇa:

(45) Squirrel's help in the construction of the bridge

The ten yojana long bridge was to be built with the stones and hills brought by Hanuman. Of these hundred yojanas, long bridge construction of only twenty yojanas was completed which was inaccessible. The demons started coming to have a look at it. Close by there was the group of squirrels. They would jump in the sea water, wet their bodies roll over the sand and then shed the sand over the bridge, which helped in plugging many holes in the bridge. Hanuman saw that many squirrels were roaming about there. He tried to get them out by terrorizing them and being unsuccessful in his attempt he caught hold of them all and then threw them here and there. All the squirrels then went to Rama with a complaint against Hanuman and told Rama that they had been terrorized by Hanuman.(82)

Rama then called for Hanuman and said, "Why have you humiliated the squirrels? All are participating in the construction of the bridge according to their capacity. Hanuman felt ashamed at this. Raghunatha is extremely kind hearted. He then moved (his affectionate) hand over the back of the squirrels. (There is a belief that the marks of Rama's fingers over the back of the squirrels are still visible in the form of the stripes on their back).(83)

All the monkeys then moved on to the bridge. Hanuman said to them, "Listen, O monkeys, do not disturb the squirrels any more."

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EDIT

I found another version of Ranganātha Rāmāyaṇa (Telugu) which does contain the squirrel episode. So it's possible this is the original and not the one I linked above.