Valmiki Ramayana Kishkindha Kanda Sarga 48 Shloka 14
Original Shlokaतेन धर्मात्मना शप्तं कृत्स्नं तत्रमहद्वनम्। अशरण्यं दुराधर्षं मृगपक्षिविवर्जितम्।।4.48.14।।
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तत्र there, महत् great, कृत्स्नम् entire, वनम् forest, अशरण्यम् barren, दुराधर्षम् unfit to harbour, मृगपक्षिविवर्जितम् without beasts and birds, तेन by him, धर्मात्मना by the righteous sage, शप्तम् cursed.
Cursed by the great righteous sage the entire forest turned barren, unfit to harbour living beings and became devoid of even beasts and birds.