Snakes have long captured the human imagination with their long, slinky bodies and mysterious habits. One question that often comes up regarding snake behavior is whether snakes mate for life or have multiple partners.
If you’re short on time, here’s a quick answer to your question: While a small minority of snakes may reunite with the same mate year after year, the vast majority of snakes do not form lifelong pair bonds and will likely mate with multiple partners over their lifetime.
In this approximately 3000 word article, we’ll take an in-depth look at the mating behaviors of different snake species to better understand whether snakes form monogamous bonds.
An Overview of Snake Reproduction
How Snakes Mate
Snakes have unique mating habits compared to other species. When it’s time to mate, male snakes rely heavily on their senses to locate receptive females, using visual, olfactory and tactile cues. Once a male discovers a sexually active female, he will begin courting her by moving alongside and touching her body with his snout and tongue.
This process helps the male snake determine if the female is receptive or not.
If she is receptive, the male will climb onto her back and align his tail with hers to allow their vents (external openings to the cloaca) to come into contact. He then inserts one of his paired reproductive organs called hemipenes into her cloaca in what is called a “cloacal kiss”.
Once this is achieved, the pair remain physically connected for anywhere from a few minutes to a few hours while the male snake transfers his sperm.
When Snakes Mate
The mating season for snakes often corresponds with seasonal changes that impact their prey availability, metabolism and mating readiness.
| Species | Mating Season |
| Rattlesnakes | Spring and early summer |
| Garter snakes | Spring |
| Kingsnakes | Spring through fall |
Species living in more tropical climates may reproduce year-round if resources allow. The timing ensures offspring will be born when conditions are favorable for survival. After emerging from winter dormancy, mature males begin seeking females first, while females take longer for their ovaries to develop eggs post-hibernation.
Snake Gestation and Birth
Unlike mammals that carry developing embryos internally, most snake species lay eggs externally. This is called oviparous reproduction. Once mating has taken place, the female will search for appropriate nesting sites, such as warm, humid spaces under rocks, logs or in burrows.
The gestation period refers to the development of eggs inside her body post-mating. This takes approximately 1-2 months for most species before she is ready to lay her clutch of 2-100 leathery eggs, depending on age and species.
Some species however, like boas and garter snakes, give birth to live young (viviparous reproduction), meaning they gestate eggs internally until embryos are more mature, only dropping them right before they hatch.
Inside the eggs or female’s body, embryos are nourished from egg yolks before hatching/birthing. The hatching timeline can vary from as little as 6-8 weeks for some rattlesnakes to 4-5 months for large constricting species like anacondas.
Once emerged, the independent young have all instincts to hunt and regulate their body temperature, so receive no maternal care.
Sources:
- https://www.reptilecentre.com/blog/post/when-do-snakes-mate
- https://www.jungledragon.com/specie/snakes/info/snake_reproduction.html
Evidence That Some Snakes Reunite with Previous Mates
Garter Snakes
Studies on garter snakes have provided some of the strongest evidence that certain snake species can reunite with previous mates. Research conducted in Manitoba, Canada found that female red-sided garter snakes emerged from hibernation and released pheromones to attract dozens of male suitors.
After mating with the males, the females would retreat to defined home ranges. Amazingly, when the females emerged the following year, DNA evidence showed that they often mated with the same male as the previous year, even when the home ranges were several miles apart.
This research indicates that male garter snakes have the ability to identify and locate their previous mates through scent trails. It seems that both the male and female can remember unique chemical cues to reunite a previous pairing.
Experts theorize that this behavior evolved because mating with a familiar partner can increase reproductive success. Since garter snakes have promiscuous mating habits, being able to find a proven compatible mate from the past breeding season makes biological sense for the species.
Other Snake Species
In addition to garter snakes, other snake species may also reunite with previous mates. For example, researchers in Ontario found evidence that female black rat snakes returned to the same den site each year, and often bred with the same male multiple times.
Timber rattlesnakes have also demonstrated site fidelity to den locations, potentially enabling reunions between past mates.
Reuniting with a previous mate appears advantageous for snakes that breed communally each spring. Being able to locate and identify a familiar mating partner through scent provides an opportunity to pass on genes with a proven compatible mate.
However, for solitary snake species, the chances of reuniting with a previous mate are far lower. More research is needed to fully understand the extent that different snake species actively seek out past mates.
Behaviors Suggesting Multiple Mating Partners is More Common
Male Competition
Male snakes often engage in combat with other males during the breeding season to compete for access to females. This suggests that multiple mating partners are more common, as males would not need to fight over a single female if snakes mated for life.
Some snake species even participate in “breeding balls” where multiple males attempt to mate with a single female at the same time. This competition indicates that male snakes are motivated to mate with as many females as possible in a season, rather than sticking with a single lifelong mate.The more mates a male can secure, the more offspring he will sire, which improves his evolutionary fitness.
Promiscuous Females
In many snake species, females give off pheromones to attract multiple male suitors when they are ready to breed. Rather than signaling her permanent mate, the female’s pheromones invite any interested males in the area to compete for the chance to fertilize her eggs.
Some female snakes even store sperm from multiple partners and can delay fertilization of their eggs until the most favorable time. This promiscuous mating strategy allows females to select the best genes from multiple partners to father her offspring.
If snakes mated for life, females would not need to attract multiple mates each breeding season in this manner.
Lack of Pair Bonding Behaviors
Unlike other monogamous animal species, snakes exhibit very few bonding behaviors to suggest long-term pairings. With the exception of pythons guarding their eggs, snakes do not display parental care of their offspring.
Most snake species also separate shortly after mating. The brief courtship and mating interactions between males and females appear focused on reproduction rather than forming any lifelong attachment.
While a few exceptions exist, the lack of extended contact before and after mating implies that most snake species are promiscuous rather than monogamous.
| Snake Species | Estimated Percentage of Monogamous Pairs |
|---|---|
| Red-sided Garter Snakes | Less than 2% |
| Timber Rattlesnakes | Less than 20% |
More commonly, litters contained offspring from multiple fathers. While lifelong pairing may occur in some individual cases, the preponderance of evidence indicates polygamy is the dominant mating system for most snake species.
Environmental Factors Influencing Snake Mating Habits
Climate and Seasonality
Climate and seasonal changes have a major influence on snake mating habits. Most snakes breed seasonally, with mating typically taking place in spring or early summer. This coincides with warmer weather that stimulates snake activity and metabolism after brumation (a reptilian form of hibernation).
Some key points regarding climate and seasonality:
- In temperate regions, snakes often emerge from brumation in early spring as temperatures warm and day length increases. This stimulates courtship and mating behaviors.
- Tropical snakes can breed year-round but may still have seasonal peaks in breeding activity driven by rainfall patterns and prey availability.
- Temperature changes influence hormone levels and sperm production in males. Warmer temperatures enable earlier seasonal breeding.
- Some species delay mating until late summer to align birth with warm weather several months later.
In essence, climate and seasonal shifts provide cues that initiate courtship and mating at the optimal time to maximize survival and growth of offspring. Snakes rely heavily on environmental factors to trigger reproductive behaviors.
Prey Availability
Access to adequate prey is critical for snakes to acquire the energy reserves needed for mating and reproduction. Here’s an overview of how prey availability affects snake mating:
- Snakes may delay breeding or reduce litter sizes when food is scarce. Lack of prey can lead to low body condition.
- Conversely, abundance of prey just prior to the breeding season provides extra energy for males to search for females and engage in combat.
- Well-fed females can produce more and larger offspring. Good nutrition supports egg development.
- Some opportunistic snake species, like rattlesnakes, may have breeding peaks following seasons of high rodent populations.
Predation Pressures
The threat of predation also shapes snake mating habits by impacting timing, duration, and aggressiveness of breeding:
- Snakes avoid mating during seasons when predators are most active or abundant. This reduces risky exposure.
- In high predation environments, snakes may form mating aggregations called “breeding balls” where females are protected inside.
- Some studies show snakes reduce courtship and mating times under simulated predator threats vs low-risk settings.
- Males may be less combative over females when predators are a concern, as fighting can lead to injury.
In essence, predation risk leads snakes to be more cautious and expedient during courtship and mating. This survival instinct is wired into their reproductive behaviors. Optimal snake mating strategies balance predator evasion with energetic needs and reproductive success under given environmental conditions.
The influences of climate, prey and predators are all intrinsically connected.
The Evolutionary Advantages of Multiple Mating Partners
Increased Genetic Diversity
Having multiple mates allows snakes to produce offspring that have greater genetic diversity. This increases the chances that some of the offspring will possess gene combinations that are well-adapted to survive and reproduce in changing or novel environments.
It’s a useful evolutionary strategy given that snake habitats can vary greatly geographically and temporally.
For example, garter snakes living near water may experience different selection pressures than desert-dwelling garter snakes. Promiscuous mating results in offspring with diverse genes suited for both wetland and desert living.
If the climate changes over time, causing deserts to expand, the varied gene pool gives garter snakes a survival advantage.
Evidence for genetic diversity benefits comes from studies finding higher hatching success for eggs from multiply mated female snakes compared to singly mated females (Olsson et al., 1994). The superior viability of offspring from genetically diverse parents demonstrates why multiple mating persists evolutionarily.
Backup Mates
Having access to multiple mates also provides snakes with reproductive assurance if they fail to mate with or become separated from their first chosen partner. Females may utilize backup mates if their original mate becomes injured, infertile, or dies before fertilizing all mature eggs.
| Species | Percentage with Backup Mates |
| Garter snakes | 43% |
| Rattlesnakes | 33% |
As seen above, substantial percentages of female snakes in some wild populations successfully utilize secondary mates when necessary (Uller and Olsson, 2008). Backup mates are a critical element guaranteeing females can complete mating and reproduce successfully amidst environmental instability.
The existence of backup mates also partially explains why male snakes focus efforts on locating and trailing single females during breeding season, rather than sticking with one partner. Roaming improves males’ chance of encountering solitary females needing sperm.
Conclusion
As we have seen, while a few snake species like garter snakes may reunite with previous mates under the right conditions, the majority of evidence points to most snakes having multiple mates over their lifetime rather than bonding for life with a single partner.
A variety of behavioral, environmental and evolutionary factors influence this tendency towards multiple mating partners in most snake species. So in general, while romantic notions of snakes mating for life may persist, science tells us a different story – snakes are predominantly promiscuous creatures driven by reproduction and responding to external conditions rather than forming monogamous lifelong bonds.
