Arthashastra
उलूक वागुली पुच्छ पुरीष जान्व् अस्थि चूर्ण पूर्णा अहि भस्त्रा पक्षिणाम् अन्तर् धानम् ॥
The slough of a snake (ahi) filled with the powder of the bone of the knee-joint mixed with that of the tail and dung (purísha) of an owl and a váguli (?), can render birds invisible.
english translation
ulUka vAgulI puccha purISa jAnv asthi cUrNa pUrNA ahi bhastrA pakSiNAm antar dhAnam ॥
hk transliteration by Sanscript