An online resource based on the award-winning nature guide

Cold-blooded Animals

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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Some Spiders Still Active

10-29-18 march fly and spider_U1A1162Spiders are ectotherms – warmed and cooled by their environment. In the fall, those outdoor species that remain alive through the winter begin preparing themselves by producing antifreeze proteins that allow their tissues to experience below-freezing temperatures. When a small particle of ice first starts to form, the antifreeze proteins bind to it and prevent the water around it from freezing, thus preventing the growth of an ice crystal. Some species survive in temperatures as low as -5 degrees Celsius.

The pictured hammock spider, still active in late October, is nourishing itself by drinking the dissolved innards of a fall-flying March fly, whose name comes from the predominantly springtime flight period of most March Flies (of the 32 species in the genus Bibio in North America, only three fly in fall).

A common belief is that once cold weather appears, outdoor spiders seek shelter inside houses.  In fact, only about 5% of the spiders you find in your house lived outside before coming into your house, according to Seattle’s Burk Museum.  The reason people tend to notice them more inside may be because sexually mature male spiders become more active in the fall, wandering far and wide in search of mates.

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Painted Turtles Basking

3-23-16 painted turtles 033Being an aquatic species, most painted turtles hibernate in the mud at the bottom of ponds. They dig down as far as ten feet where they spend the winter hovering around 43°.  In the spring, when the temperature of the water approaches 60°, painted turtles begin actively foraging, but the first priority upon awakening is to warm up their bodies.  Turtles are ectothermic, or cold-blooded, thus the temperature of their bodies is determined by the  environment that surrounds them.  To be active, painted turtles must maintain an internal temperature of 63°- 73°.  They reach and maintain this temperature by basking in the sun, particularly in the cold, first weeks of spring.  Once warmed up, the turtles will forage, and when they begin to cool off, basking resumes.

Competition for basking sites such as floating logs and rocks can be fierce.  It is not unusual to see many painted turtles lined up on a floating log, or turtles piled one upon the other on a rock in an effort to maximize the effect of the sun’s rays.  The heat they’re obtaining increases their metabolism, aids in digestion and allows males to start producing sperm.  The sun also strengthens their shells and reduces the amount of algae on them, thereby reducing the chances of bacterial or fungal infection.

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