Valmiki Ramayana Bala Kanda Sarga 24 Shloka 13

झिल्लिकागणनादितम् having ceaseless sounds of crickets, भैरवै: by the frightful, श्वापदै: ferocious beasts, दारुणारुतै: creating fearful cries, शकुन्तै: by birds, पूर्णम् filled, इदम् this, वनम् forest, दुर्गम् inaccessible, अहो what a wonder.

"What a wonder This inaccessible forest echoes with the (shrill) chirpings of crickets It is filled with ferocious beasts and birds producing fearful sounds.