Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 20
Sanskrit:
हंसपारावतव्रातैस्तत्र तत्र निकूजितम् ।कृत्रिमान् मन्यमानै: स्वानधिरुह्याधिरुह्य च ॥ २० ॥
ITRANS:
haṁsa-pārāvata-vrātaistatra tatra nikūjitamkṛtrimān manyamānaiḥ svānadhiruhyādhiruhya ca
Translation:
Here and there in that palace were multitudes of live swans and pigeons, as well as artificial swans and pigeons so lifelike that the real swans rose above them again and again, thinking them live birds like themselves. Thus the palace vibrated with the sounds of these birds.