..." According to Munro (1950:88), "head bobbing" appears to be a sign of annoyance in some instances but is usually concerned with reproduction and individual recognition... 
Ray D. Burkett 「Natural History of Cottonmouth Moccasin, Agkistrodon piscovorus (Reptilia)」
...James Munro, manager of the ranch, also rendered valuableassistance...
Gerard Fowke 「Archeological Investigations」
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