The potential for seed rescue and secondary dispersal in rattlesnakes

Abstract Although snakes have a nearly worldwide distribution and are a speciose (>4000 taxa) and important group of predators of seed-eating animals, few studies have explored their potential role in diploendozoochory. Here, we use two widespread species of the Sonoran Desert, the foothill palo verde tree (Parkinsonia microphylla) and captive-held western diamondback rattlesnakes (Crotalus atrox), to determine if seeds that have passed through the snakes’ digestive tract remain viable and capable of germination up to 1 year post gut transit. Additionally, we tested whether the presence of rattlesnake excrement (faeces and urates) influenced seed germination success. Germination trials were conducted in natural summer conditions in Phoenix, Arizona. We found seeds exposed to snake gut-transit can remain viable and that seeds planted with excrement from which they were recovered had higher germination (40.07%) than seeds planted without excrement (28.95%) and compared to control seeds with no snake exposure (28.2%). These findings suggest that snake excrement may facilitate germination and that western diamondback rattlesnakes have the potential to act as seed rescue and secondary dispersal agents. In light of the emerging global seed dispersal crisis, our results highlight the need for broader studies into the role of diploendozoochory in snakes worldwide.