A Rattlesnake Helper?

Priscilla, Lois, and Arli (Arizona Black Rattlesnakes) spent their pregnancy together at a rookery from May through August, 2010. Arli moved away to a private nest shortly before giving birth, while Priscilla and Lois stayed at the rookery.

On 30 August 2010 we observed Priscilla (pregnant adult female) discouraging House (neonate / newborn) from potential exposure to a human predator. Because Priscilla was pregnant at this time, House had a different mother. To our knowledge, this is the first observation of helping – where an animal cares for another’s offspring – in a snake. Perhaps this is why some female rattlesnakes aggregate during gestation and remain together after giving birth.

  • House, a newborn Arizona Black Rattlesnake, rests among Priscilla’s coils. Priscilla is still pregnant here; House is her nestmate’s baby.
  • 15:27 Priscilla (adult female) and House (neonate) are at rest in a shaded rock shelter.
  • 15:28 House moves restlessly in cover and then begins to move toward open ground.
  • 15:29 Priscilla swiftly confronts House before he wanders away from cover; her posture is unusually rigid.
  • 15:31 House stops, turns around, and coils in cover. Priscilla’s head returns to her coils.