What better way to test the response of a brown tree snake to blood than to toss them in a tank with bloddy tampons and count how often they flick their tongue at the blood.

Ten specimens of Boiga irregularis were presented with clean or bloody tampons. The latter were used by women during menses. Trial duration was 60 sec, intertrial interval was 24 hr, and the dependent variable was rate of tongue flicking (a measure of chemosensory investigation). Bloody tampons elicited significantly more tongue flicking than did control tampons. An additional snake is shown attacking and ingesting a soiled tampon, confirming that chemosensory interest was associated with predatory behavior.