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Reptiles

Snapping Turtles Laying Eggs – Sex Of Turtles Determined By Temperature

6-21-19 snapping turtle 1B0A1038It’s that time of year again, when female Snapping Turtles are leaving ponds, digging holes in sandy soil and depositing up to 80 eggs (20-30 is typical) before covering them up and returning to their ponds. While the sex of most snakes and lizards is determined by sex chromosomes at the time of fertilization, the sex of most turtles is determined by the environment after fertilization. In these reptiles, the temperature of the eggs during a certain period of development is the deciding factor in determining sex, and small changes in temperature can cause dramatic changes in the sex ratio.

Often, eggs incubated at low temperatures (72°F – 80°F) produce one sex, whereas eggs incubated at higher temperatures (86°F and above) produce the other. There is only a small range of temperatures that permits both males and females to hatch from the same brood of eggs. The eggs of the Snapping Turtle become female at either cool (72°F or lower) or hot (82°F or above) temperatures. Between these extremes, males predominate. (Developmental Biology by S. Gilbert)

If the cool temperatures we’ve experienced thus far this spring continue, there could be a lot of female Snapping Turtles climbing up out of the earth come September. (Thanks to Clyde Jenne and Jeffrey Hamelman for photo opportunity)

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Northern Water Snakes Courting & Mating

9-19-19 mating water snakes by Jeff Mazur IMG_9688 (002)Northern Water Snakes (Nerodia sipedon) are non-poisonous snakes which, as their name implies, tend to be found in the Northeast, in and around water. Females (bottom snake in photo) are heavier and longer than males (as long as five feet) and grow much faster. Since the end of May, Northern Water Snakes have been engaging in courtship rituals and mating. The male snake (top snake in photo) begins by crawling alongside a female while he rubs his body along hers. It is not unusual for more than one male to court her at the same time, with one eventually achieving copulation by twisting and coiling his tail around her body and tail as he attempts to get their cloacae aligned.

Northern Water Snakes are ovoviviparous – the female’s eggs incubate inside her body. The larger the female, the greater the number of live young she’s likely to produce in late August or September. Northern Water Snakes have between 12 and 60 young — judging from the size of the pictured female she’ll have a large litter. (Photo by Jeff Mazur)

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Painted Turtles Basking

5-1-19 painted turtle_U1A7417Water temperature of fifty-nine degrees Fahrenheit is the magic number for Painted Turtles in the fall. Below it, their metabolism slows to a near standstill – their heartbeat slows to only one beat every few minutes and they do not breathe through their lungs (if conditions allow, they may absorb oxygen dissolved in the water through specialized skin cells near the tail). Their body temperature averages 43°F. when hibernating in the mud at the bottom of ponds. Occasionally a Painted Turtle is seen swimming under the ice, but for the most part, hibernation rules from October to April in northern New England.

When the water reaches 59°F.- 64°F. in the spring, Painted Turtles become active again. In addition to foraging, they immediately start basking in the sun. Being cold-blooded, or ectothermic, they need this external source of heat to warm their body, but the UV light also regulates their metabolism and breeding as well as helps produce Vitamin D3, which is essential for the health of their bones as well as their internal organs.

Basking can also help relieve aquatic turtles of ectoparasites. Leeches are a blood-sucking ectoparasite that can cause anemia in reptiles. Drying out in the sun causes the leeches to shrivel up and die. Algae on basking aquatic turtles can also dry out and fall off, allowing the shells to retain their aerodynamic nature.

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Snapping Turtles Emerging From Hibernation

4-19-19 snapping turtle1 _U1A6737Congratulations to Elizabeth Hall, the first reader to correctly identify the trail blazer in the previous NC post!

As you can see from the dirt piled on this Snapping Turtle’s head, it has just emerged from hibernation. After extracting themselves from their muddy hibernacula, Snapping Turtles have two missions: to raise their body temperature and to secure food. According to Jim Andrews, Director of the Vermont Reptile and Amphibian Atlas (https://www.vtherpatlas.org/ ), the first movement of the year for these turtles is often to seek shallow water where they can bask in the sun and heat their internal organs. They also are on the move in order to get from their overwintering site (shallows of ponds, marshes, and lakeshores, in a spring or a stream) back to a feeding area. It won’t be long before they will be searching for mates.

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Common Gartersnakes Brumating

1-28-19 gartersnake img_4888Somewhere 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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Snapping Turtles Entering Hibernation

10-22-18 snapper IMG_5801Most Snapping Turtles have entered hibernation by late October. To hibernate, they burrow into the debris or mud bottom of ponds or lakes, settle beneath logs, or retreat into muskrat burrows or lodges.  Once a pond is frozen over, how do they breathe with ice preventing them from coming up for air?

Because turtles are ectotherms, or cold-blooded, their body temperature is the same as their surroundings.  The water at the bottom of a pond is usually only a few degrees above freezing.  Fortunately, a cold turtle in cold water/mud has a slow metabolism.  The colder it gets, the slower its metabolism, which means there is less and less of a demand for energy and oxygen as temperatures fall – but there is still some.

When hibernating, Snapping Turtles rely on stored energy.  They acquire oxygen from pond water moving across the surface of their body, which is highly vascularized.  Blood vessels are particularly concentrated near the turtle’s tail, allowing the Snapper to obtain the necessary amount of oxygen to stay alive without using its lungs.

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Young Milk Snakes Soon To Hibernate

10-17-18 milk snake young _U1A0781The eggs that Milk Snakes laid last June or July hatched recently and the six-inch young snakes as well as the adults that produced them will only be evident (and then, mostly at night) for the next few weeks.  Hibernation is around the corner, and these snakes often seek out the cellars of old houses with stone foundations in which to spend the winter.  Should you come upon a Milk Snake, please spare its life. They are not poisonous, and you couldn’t ask for a more efficient mouse catcher (Mice accounted for 74 percent of a study of Milk Snakes’ stomach contents.).

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