Valmiki Ramayana Yuddha Kanda Sarga 4 Shloka 65
Original Shlokaतत्र केचिद्द्रुतं जग्मुरुत्पेतुश्च तथापरे । केचित्किलकिलां चक्रुर्वानरा वनगोचराः ।।6.4.65।।
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तत्र being so, वनगोचराः inhabitants of forests, vanaras, केचित् some, वानराः vanaras, द्रुतम् swiftly , जग्मु went, तथा so also, अपरे others, उत्पेतुश्च jumped, केचित् some, किलकिलाम् made sounds like 'kila kila', चक्रुः went
Being vanaras some went swiftly, some jumped, and some others made sound 'kila kila'(the usual sounds of monkeys) while they went.