Breeding is a major part of all animal life cycles, and this is no different for rattlesnakes.  Like other reptiles there are separate sexes, and internal fertilization is the rule.  For this to happen, during breeding season males must find the females and often must compete with other males for the right to breed.

Breeding typically occurs in the spring shortly after emerging from hibernation.  The females are hungry from hibernating, but they must gain fat to help feed the developing young.  In reptiles’ embryonic development usually occurs within an egg.  Within this egg the developing embryo is connected to a yolk sac from which they feed.  There is another attached sac called the allantois which is where they go to the bathroom.  When the yolk sac is gone and the allantois is full, it is time to hatch.  It is the mother’s job to produce this egg and place it somewhere where it will remain warm and protected.  But here the rattlesnakes are a bit different.

They differ in that though they produce eggs, they do not lay them in a nest.  Rather she keeps the eggs within her body for warmth and protection.  The covering of their eggs is more of a membrane rather than a shell.  During this gestation period, the females will find a hiding place where she can still access sunlight.  She will position herself so that her body remains warm for her offspring and then lie for 2-3 months until they are born.  Though she may drink, she usually does not eat during the period.

The mother typically produces about dozen such eggs and they emerge in early fall.  The young are venomous and innately understand how to survive.  However, the mother often stays with them until they shed their first skin, at which time she will leave them on their own.  She will then binge feed preparing for the upcoming hibernation period.

Some females will breed again in the fall.  These will store the sperm during hibernation and fertilize their eggs in the spring.  During both the spring and fall breeding periods the males will venture far and wide to find females.  It is during these periods when many come into contact with people in strange places.  The drive to find females will have them move into neighborhoods and human habitats that they would otherwise avoid.

Rattlesnakes live around 25 years.  They become sexually mature in 6-7 years but do not breed every year.  It has been estimated that only one of the 12 or so newborns will make it to the age of three.  With the infrequent breeding of adults and low success rate of the offspring, rattlesnakes are susceptible to population declines when adults are removed.  The loss of habitat, road kills, decline in prey, natural predation, and indiscriminate killing by human’s rattlesnake populations can suffer, and many are considered species of concern.

Next, we will look at predator/prey interactions with rattlesnakes.

References

Rubio, M. 2010. Rattlesnakes of the United States and Canada. ECO Herpetological Publishing & Distribution. Rodeo, New Mexico. pp. 307.

Gibbons, W., Dorcas, M. 2005. Snakes of the Southeast. The University of Georgia Press. Athens, Georgia. pp. 253.

Graham, S.P. 2018. American Snakes. John’s Hopkins University Press. Baltimore, Maryland. pp. 293.

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