I recently got a young pair of Panamanian BCI. Both just shed recently and passed their last meals so they're out cruising around today. The male is in a plastic tub with a transparent lid and sides. As I leaned over the top to look down at him through the lid, he thrashed his tail around quickly for about 1 second. Nothing happened while I was motionless, but any time I made a sudden move he would thrash his tail for just a moment.
It was kind of like caudal luring, but faster and more forceful. I got down to look through the side of the enclosure and the same behavior occurred. His entire body was motionless other than the tail the whole time. If I loom over my Nics or do anything that worries them, they just turn to face me and assume a defensive posture. So I've never experienced this before and I've never heard of a boa using its tail to draw attention away from its head when threatened-am I just out of the loop on this?


