The Shalya Parva of Mahabharat while describing the gifts of different arms to Kartikeya mentions the following:
Garuda gave him his favourite son, a peacock of beautiful feathers. Aruna gave him a cock of sharp talons. The royal Varuna gave him a snake of great energy and might. The lord Brahma gave unto that god devoted to Brahman a black deer-skin. And the Creator of all the worlds also gave him victory in all battles.
Is the story of origin of peacocks from Garud detailed in any scripture?
Yes, Vayu Purana, Chapter 69 gives the details about the progeny of Garuda. It mention that peacocks were originated from Garuda with his wife Bhasi.
भार्या गरुत्मतश्चापि भासी क्रोझी तथा शुकी।
धृतराष्ट्री च भद्रा च तास्वपत्यानि वक्ष्यते (च्म्यहम्)।The spouses of Garutman were- Bhasi, Kraunct, Suki, Dhrtarastri and Bhadra. Their progenies are being enumerated.
शुकी गरुत्मतः पुत्रान्सुषुवे षट् परिश्रुतान्।
त्रिशिरं सुसुखं चैव बलं पृष्ठं महाबलम्॥ ३२९॥
त्रिशडुनेत्र सुसुखं सुरूपं सुरसं बलम्।
एषां पुत्राश्च पौत्राश्च गरुडानां महात्मनाम्॥ ३३० ॥
चतुर्दश सहस्राणि क्रूराणां पन्नगाशिनाम्।
पुत्रपौत्रविसर्गाच्च तेषां वै वंशविस्तरः॥ ३३१॥Suki produced six well-known sons from Garutmān, viz. the Sweet-faced Triśira, Bala, Prșțha of great valour, Triśaṁkhanetra, Sumukha of good form and the powerful Surasa. The sons and grandsons of these ruthless descendants of Garuda, the great-souled serpent-eaters, were numbered fourteen thousand. By procreation of Sons and grandsons their family became extensive.
व्याप्तानि यानि देशानि (स्थानानि) तानि वक्ष्ये यथाक्रमम्।
शाल्मलिद्वीपमखिलं देवकूटं च पर्वतम्॥ ३३२॥
मणिमन्तं च शैलेन्द्र सहस्त्रशिखरं तथा।
पर्णमालं सुकेशं च शतशृङ्गं तथाऽचलम्॥३३३॥
कौरज पश्चशिखरं हेमकूट च पर्वतम्।
प्रचण्डवायुप्रभवैर्दीपितैः पद्मरागिभिः॥ ३३४॥
शैलजालानि व्याप्तानि गारुडैस्तैर्महात्मभिः।
भासीपुत्राः स्मृता भासा उलूकाः काककुक्कुटाः।And the lands where they spread themselves, I shall dilate upon them in a serial order. They are- Salmalidvipa in entirety, the mountain Devakula, the lordly mountains Manimán of thousand peaks, Parnamala, Sukeśa, Šatašrnga, Kauraja, Pañcaśikhara and Hemakuta. All these mountains were occupied by the noble-souled descendants of Garuda. They were brightened with ruby stones and they produced gusts of violent winds. Bhasas (the bird Vulture), Ulukas (owls), crows and cocks were the sons of Bhasi.
मयूराः कलविङ्काश्च कपोता लावतित्तिराः।
क्रोक्की वार्धणिसाञ्श्येनी कुररान्सारसान्बकान्।Peacocks, Kalavinikas (sparrows), Kapotas (doves), Lavas (quails) and Tittiris (partridges) also were born of Bhasi. Kraufic created Vardhinasa birds (black birds with red legs, head and eyes). Syeni created Kuraras (ospreys), Sarasas (cranes) and Bakas.
इत्येवमादयोऽन्येऽपि कव्यादा ये च पक्षिणः।
धृतराष्ट्री च हंसाच कलहंसाश्च भामिनी। ३३७।
चक्रवाकांच विन्द्रग्रान्सर्वाचैवादकाजिहान्।
एतानेव विजज्ञेऽथ पुत्रपौत्रमनन्तकम्॥ ३३८॥She gave birth to other birds of prey also like these. The beautiful lady Dhrtarastri created Harinsas and Kalaharinsas, Cakra vākas and other types of aquatic birds too. These were the birds given birth to and their sons and grandsons were infinite.
गरुडस्याऽऽत्मजाः प्रोक्ता इरायाः शृणुत प्रजाः।
इरा प्रजज्ञे कन्या वै तिस्रः कमललोचनाः।। ३३९ ॥The offsprings of Garuda have been enumerated. Listen to the progeny of Ira. Ira produced three daughters with lotus like eyes.
