Manava Dharmashastra 11.142

11.142

phaladānāṃ tu vṛkṣāṇāṃ chedane japyam ṛkśatam
gulmavallīlatānāṃ ca puṣpitānāṃ ca vīrudhām //

But for killing (small) animals which have bones, he should give some trifle to a Brahmana; if he injures boneless (animals), he becomes pure by a suppressing his breath (pranayama).