Common Gartersnakes Emerging From Hibernation
Snakes, being cold-blooded, or ectotherms, must find a spot to spend the winter where their bodies will not freeze. Not being able to dig their own dens, or hibernacula, snakes often rely on natural cavities and the burrows of other animals such as woodchucks and chipmunks that are below the frost line. During winter, typically between October and March, a hundred or more individuals of different species can gather in the same den, slowing down their metabolism and tightly coiling their bodies together to stay warm enough to survive.
Once the earth starts to warm up, snakes emerge. Common Gartersnakes remain near their winter dens for several days. Males appear first in the spring, sometimes in groups as large as several hundred snakes. Females tend to emerge singly and over a longer period of time. Gartersnake courtship soon follows and can take the form of a writhing mass of bodies, called a mating ball, where one female is surrounded by and has her pick of a hundred or more lustful males.
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Why Do Snakes Bask?
Snakes, like other reptiles, are cold-blooded – they are unable to internally regulate their body temperature. On cool days If their body temperature is low, they are sluggish. They don’t move quickly, don’t hunt effectively and if they have food in their stomachs, digestion comes to nearly a standstill.
They avoid this situation by basking when cool weather sets in. They lay in the sunshine and/or on rocks or substrate that is heated by the sun, and warm up. When they get to an optimal temperature, they can be active, hunt and digest the food they eat. During these shorter, cooler fall days, before snakes enter hibernation, a great deal of time is spent basking.
There is an advantage to using sunlight to control body temperature. Warm-blooded animals must eat a large amount of food fairly continuously because it is the digestion of the food that regulates their body temperature and produces heat, which they must maintain in order to survive. Cold-blooded animals don’t have this restriction since their body temperature is controlled externally. This is why a snake can go for a relatively long period of time (months, depending on species) without eating after it has consumed food. (Photo: Common Gartersnake peering out from under leaves after its basking was disturbed)
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Common Gartersnakes Mating
During these first days of April, Common Gartersnakes emerge from their hibernacula and often bask in the sun near the den where they spent the winter. (At this time they are more approachable than later in the season, should you desire a close look at one.) Males usually appear first; when the females appear, the males follow them in hot pursuit.
Common Gartersnakes are known for their impressive courtship ritual. Prior to copulation, as many as a hundred males will often writhe around a single female, forming a mass which is referred to as a “mating ball.” The male closest to the female rubs his chin on the head, back and sides of the female while aligning himself with her and eventually mating takes place. When it does, the other males that were in the mating ball leave and seek out other females. Female gartersnakes mate once; male may mate with several females. (Photo by Sally Fellows)
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Common Gartersnakes Brumating
Somewhere between two and four feet (depending on where you live in New England) beneath our feet there is a “frost line” below which the ground water in soil doesn’t freeze. Snakes, being reptiles, are ectotherms, and their bodies assume the temperature of the air around them. In order to avoid being frozen to death in the winter, they retreat below the frost line, where they enter a state called brumation – the cold-blooded term for a state of torpor and inactivity that is not true hibernation, but in which a dramatic slowing down of bodily functions occurs. Crevices in south-facing rocky ledges and abandoned woodchuck, fox and skunk dens (and human cellars) often serve as hibernacula, or winter shelters. Common Gartersnakes are known to gather in large numbers (one Canadian den served as a hibernaculum for 8,000 gartersnakes), in order to concentrate the small amount of heat their bodies produce in the winter.
As the air temperature lowers in the fall, a snake’s body temperature falls and its metabolism decreases dramatically. Gartersnakes actively prepare for this by not eating for several weeks prior to hibernating. This allows all of the food they previously consumed to be completely broken down and absorbed into their system. To enhance this process, gartersnakes bask in the sun both before and during their early days of sheltering in hibernacula, warming themselves so as to increase the rate of their metabolism just prior to hibernating.
Should a snake happen to eat a large grasshopper, earthworm or small frog just prior to entering brumation, the snake may become extremely lethargic due to the slowing down of its metabolism, and the contents of its stomach may not be digested as quickly. The longer it takes to process food in its stomach, the greater the chances that this dead material will start to decay, which could result in serious illness to the snake.
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Young Common Gartersnakes Appearing
Seventy percent of the world’s snakes lay eggs (oviparous). The rest give birth to live young (viviparous). Oviparous snakes tend to live in warmer climates, where the substrate they lay their eggs in is warm enough to incubate the eggs. (Most egg-laying snakes deposit their eggs and then depart, relying on the substrate to incubate the eggs.) Viviparous snakes tend to live in cooler regions, where the ground is too cold to provide incubation.
There is a distinction between egg-laying snakes. The majority of snakes that lay eggs do so outside their body, in a protected area such as a rotting log. These snakes are known as oviparous. There are also egg-laying snakes that retain their eggs inside their bodies until they’re ready to hatch. These snakes are called ovoviviparous. Ovoviviparous snakes, such as the Common Gartersnake, appear to give birth to live young, but they actually don’t. Unlike viviparous species, there is no placental connection, or transfer of fluids, between mothers and babies, because the developing young snakes feed on the substances contained in their individual eggs. The snakes emerge from the mother when they hatch from their eggs, giving them the appearance of “live” births. The gestation period for oviparous snakes is generally longer than those of ovoviviparous snakes and vary from a few weeks to a few months in length. (Photo: very young Common Gartersnake, Thamnophis sirtalis sirtalis, consuming an earthworm)
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Common Gartersnakes Mating
Common Gartersnakes begin mating in the spring as soon as they emerge from brumation (a reptilian state of dormancy similar to hibernation in mammals, but involving different metabolic processes). The males leave the den first and wait for the females to exit. Once the females leave the den the males surround them, forming what is called a mating ball (one female and many males). The males give off pheromones that attract the female. After the female has chosen her mate and mated, she leaves. while the males stay to re-mate with other available females. The females have the ability to store the male’s sperm until it is needed and thus a female may not mate if she does not find a proper partner.
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Common Gartersnakes Giving Birth
Common Gartersnakes mate soon after emerging from hibernation in the spring, in March or April, and four months later the females give birth to live young. The newborn snakes are 5 to 9 inches long at birth and from day one have to fend for themselves. Their diet at this early stage consists of earthworms, insects, slugs, tadpoles, small frogs and fish. If there is an abundant supply of food, the young snakes can grow as much as 1 ½ inches a month during their first year. Earthworms are their preferred diet and gartersnakes are known for their ability to find them, even underground. It turns out that earthworms produce a chemical substance in their skin that is easily detected by (and attractive to) Common Gartersnakes. (Thanks to Eli Holland, who located the worm-eating newborn Common Gartersnake in the photograph.)
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