Megan's Nature Nook
Nature Notes, Phenology, Photography, Fun Facts, Trips, Maybe Even a Bad Joke or Two... and More!
Winter and cold temperatures have finally hit us in Minnesota. Many birds (and some insects) migrate to escape the cold, other animals grow thick winter coats and adapt their diets to what is available, while others decide to skip the cold weather and just sleep through it. These tactics are all great ways to survive harsh winters, but did you know that some animals actually survive cold weather by freezing themselves and thawing out in the Spring? Usually freezing is not a good thing for living organisms - think frostbite. When ice forms, cells can be pierced by the growth of sharp ice crystals or the cell can rupture because of the expansion of fluids in the cell resulting in the death of the cell. Luckily some animals have special cryoprotectant (cryo = ice, cold, frost in Greek) substances in their tissue that protects the tissue from freezing and being damaged. Wood Frog Wood frogs (Lithobates sylvaticus) live in wooded areas and when cold weather approaches they bury themselves under leaf litter just under the surface of the soil. They can freeze up to 70% of their body including the brain and lenses of the eyes. Their heart completely stops, their breathing stops, and there is no muscle movement. Then in Spring when their body warms up, water will return to the cells and the frog returns to normal functions. They will repeat this process each year. How can they freeze and essentially cease to live for such a long time? Wood frogs have special nucleating proteins that suck most of the water out of their cells. The liver produces glucose (sugar) to fill the cells and prevents them from freezing solid and rupturing. This natural antifreeze protects their cells in cold weather. Woolly Bear Caterpillar Woolly Bear Caterpillars (Pyrrharctia isabella) are the larval stage of the Isabella Tiger Moth. These fuzzy black and brown caterpillars are usually seen in the fall as they search for their overwintering spots inside cavities, under leaves, rocks, logs, or bark. Their long “fur,” called setae, helps them to freeze more controllably. They produce a natural antifreeze called glycerol which keeps cells from fully freezing and bursting. Woolly Bear Caterpillars will spend winter in this mostly frozen state and will thaw in the Spring and make a cocoon, later emerging as a moth. These small yet mighty insects can survive down to -90°F! Painted Turtle Hatchling
Painted Turtles (Chrysemys picta) lay their eggs in early summer (June) and they hatch in late summer (August). Although many turtle hatchlings will emerge from the nest to start their new lives, some will overwinter as hatchlings underground in the nest. Environmental cues dictate whether the turtles should emerge or stay in the nest for winter. Painted Turtle hatchlings can do something called supercooling. They’re able to lower their body temperature to as low as 10°F without having their body fluids freeze. They’re able to do this because they don’t have Ice Nucleating Agents (INAs) internally. INAs are particles that an ice crystal can form around. So without INAs they can cool below freezing without ice forming and causing damage to the cells. It’s pretty amazing what each of these small creatures can do to survive our harsh winters! Animals have a variety of ways to help them survive winter, but I think freezing themselves and being able to thaw out in the spring is one of the most unique ways! As you bundle up to enjoy the great outdoors this winter, think of all the animal popsicles that may be hiding just out of sight awaiting the warmth of Spring.
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Some of you may have notices that I’ve been on a bit of a hiatus from blogging lately, and I apologize, but I have a good excuse – I’ve been busy wedding planning, getting married, and on our honeymoon! Tony and I spent our honeymoon on the North Shore of Minnesota and when hiking at Jay Cooke State Park, were lucky enough to spot a Ringneck Snake! Neither of us had seen one before so it’s a new one to add to the critter list. We were hiking around in a rocky, wooded area near the river when something slithered across the path. I quickly stepped to the side away from it, but of course Tony had to know what it was so he went right for it and was able to catch it. He held it just long enough for a good look and a few pictures, then released it. We later found out that this was the first reported sighting of a Ringneck snake in Carlton county! We were able to report it to www.mnHerps.com which is a great resource for amphibian and reptiles of Minnesota. Ringneck snakes (Diadophis punctatus) Identification Ringneck snakes are a small black or dark grey snake with a yellow or orange ring around the neck and a yellow-orange belly that may have black spots (depending on the subspecies). They can grow to be 10-15 inches long.
Diet
Small animals like lizards, frogs, slugs, insects, earthworms, and smaller (usually baby) snakes. Predators Bullfrogs, Raptors, Striped Skunk, Virginia opossum, other larger snakes will prey on Ringnecks. When threatened they will coil up their tails into a corkscrew to show off the bright red or orangish underside of their tails. Venom Ringnecks do not have a true venom gland but their saliva contains a mild venom – which is used to subdue prey. They inject their venom through channeled teeth that are located near the rear of the mouth, because of this they need to chow on their prey in order to inject the venom. The venom is so mild that it won’t harm humans. Fun Facts There are 14 recognized subspecies of Ringnecks. Minnesota has two of those – the Northern Ringneck (Diadophis punctatus edwardsii) found in forests in the Northeastern part of the state and the Prairie Ringneck (Diadophis punctatus arnyi) found in the Southeastern part of the state. Keep your eyes open when you're out and about, you never know what you might stumble upon! It’s turtle time! You have probably been seeing turtles around, either basking on logs, swimming in the lake, or crossing the road. Minnesota’s 10,000 lakes are home to nine species of turtles. Towards the end of May and into June turtles are often seen crossing roads as they are heading to nesting spots. Unfortunately for the turtles, nesting time can be a dangerous part of their lives, but there are a few things we can do to help these interesting creatures. Check out this PDF from the MN Department of Natural Resources about our turtles. Nesting Sites Snapping and Painted Turtles are the ones we most often see, especially during nesting season. When looking for a nesting site, females will look for soft, sandy soil that has lots of sun exposure. She will use her back legs to dig a hole the shape of a cereal box where she will lay her eggs. Eggs are soft and have a leathery shell. The whole nesting process takes 3-4 hours, and often happens in the evening or mornings. Snapping turtles lay 20-40 eggs, and Painted turtles lay 4-15 eggs. Once the eggs are laid the female will cover them with the soil or sand that was dug out and then leaves the nest. Incubation (done by the sun) takes 2-3 months and the hatchlings will emerge in mid to late August, or even into September for some Snapping turtles. Turtles do not have sex chromosomes, so the sex of the hatchlings will be determined by the temperature during incubation. Warmer temps will yield females, while cooler temps result in males. Raccoons, mink, skunks, and foxes are common predators of turtle eggs, often digging up nests within 48 hours of the eggs being laid. Nests can be protected from predators by placing a wire fence or cage around the nest area. Be sure to remove the wire by August 1st so the hatchlings can get out once they hatch. Occasionally, the eggs will overwinter and hatch in the spring. Helping Turtles Cross the Road
Unfortunately for many turtles, finding that perfect nesting spot puts them in danger as they cross roads. Although they are crossing roads in areas which may not make much sense to us, the turtles are going to familiar nesting spots and know where they are going. If you see a turtle crossing the road there are a few things you can do to help.
Turtle Rehabilitation When I was an intern at the Northwoods Wildlife Center in Minocqua, WI the summer of 2015, we got quite a few turtles in that had been hit by cars. If it was just a shell injury where they had been hit and the shell cracked, we were usually able to fix them up and release the turtle. We would use zip ties and superglue to fix them back up. We glued the zip ties onto the shell then would gradually tighten the zip ties over a few days so the shell would no longer have gaps, then once the gaps were closed up, we could glue the shell and over time the turtle’s shell would heal completely. The shell is made of bone, so the glue would hold it in place until it had time to heal, much like a cast does when we break a bone. If you find a turtle in need a rehabilitation, look up your nearest wildlife rehabilitation center so it can get the proper care needed. As you’re driving around this turtle season, pledge to Brake for Turtles and help them cross the road when you can! Keep your eyes open in August and see if you can spot any hatchlings emerging. Why did the turtle cross the road? To get to the Shell station! |
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