Coiling During Male-Male Combat in Snakes: Differences Between Vipers and Other Groups, and Between Constrictors and Non-Constrictors

Abstract

During male-male combat (MMC) in snakes, combatants often coil around each other. To determine whether there are differences in this behavior between different snake groups, we examined video footage of 100 instances of MMC in 49 snake species from six families. Results show that in Viperidae, MMC involves smaller numbers of loops than in the other three clades considered here (Pythonidae+Loxocemidae, Elapidae+Pseudoxyrhophiidae, and Colubridae). In Viperidae, coiling also seems to be an accidental result of other movements and does not involve coil tightening, whereas in the other three clades it appears to be deliberate and is often enhanced by coil tightening. The duration of coiling is shorter in the clade Elapidae+Pseudoxyrhophiidae (most of which are non-constrictors) and Viperidae (non-constrictors) than it is in Colubridae (many of which are constrictors) and the clade Pythonidae+Loxocemidae (constrictors). It is also shorter in non-constricting colubrids than in constricting colubrids, although the number of loops does not differ between the two groups. We conclude that coiling is of lesser importance for MMC in Viperidae than in the other three clades, and that maintaining loops during MMC is of lesser importance in non-constricting groups than in constrictors. These results show that differences in the amount of coiling during MMC in snakes follow phylogenetic lines. The videos used in this study were collected from social media and demonstrate that social media can be useful in collecting data for scientific studies.