Nature Blog

Ripples 10/29/20

Written by Kennedy Zittel, Woodland Dunes intern

Halloween is almost here! With that being said, I have another scary tale to share. This time it is about zombies! Picture this, it is mid-winter, the temperature is well below freezing, ponds have frozen over, and snow is piled all around. Below the soil and water there lies a creature who has frozen solid, whose heart has stopped beating, and who has long since stopped breathing. It certainly sounds like that creature has croaked. Fast forward to spring, the temperature is rising, the sun begins to shine more, and the ground and ponds begin to thaw. To your horror, the creature mentioned earlier unburies itself and rises to the surface. Ah! But, it is just a frog. No worries though, there really is no such thing as a zombie frog, but frogs and toads do possess a unique adaption that allows them to be able to survive the harsh winter. 

photo of frozen wood frogFrogs and toads are coldblooded, meaning that their body temperature will become the temperature of the environment around them. Imagine your body turning the same temperature as the weather outside, brrr! During the winter, frogs and toads will go into a state of hibernation. One common myth about how aquatic frogs hibernate is that they will burrow themselves completely under the mud, however, if the frogs were to go completely under the mud they would not have enough oxygen to survive. Aquatic frogs instead spend the majority of winter either lying on top of the mud or partially buried in mud so that they can reach the oxygen-rich water. Terrestrial frogs and American Toads (Wisconsin’s only toad species) will often hibernate on land by burrowing deep into the soil below the frost line. Terrestrial frogs that are not as well adapted to digging, like the Spring Peeper, will seek out cracks or crevices in rocks and logs to hibernate in instead. The Wood Frog hibernates closest to the surface which is why you will hear their calls the earliest in the spring as they are usually the first then to emerge.

How do the frogs come back to life then, if they aren’t actually zombies? Well, the frogs never technically die, even though their breathing and heart do stop. They actually end up completely frozen solid (like a frog-cicle!) as the weather gets well below freezing. As ice crystals begin to form underneath the frog’s skin parts of the frog’s body will begin to freeze completely solid. The only part of a frog or toad that does not freeze completely is their vital organs. A large concentration of glucose within a frog’s vital organs will act as a natural antifreeze thus preventing vital organs like the heart and lungs from fully freezing. When the weather warms up to above freezing, the frogs and toads will begin to thaw, their hearts will begin to beat once more, their lungs will begin to work again, and come spring they will unbury themselves and rise to the surface. The ability that frogs and toads have (along with other coldblooded animals of the area) to be able to survive after freezing allows them to live in the toughest of winter climates that would have us scrambling for our heaviest winter coats. Which in my opinion, is toad-ally awesome!

photo of a frozen wood frog from National Park Service

Ripples 10/23/20

We staff at Woodland Dunes see our place in the world as a haven for both wildlife and people. Each year we spend some time trying to measure the diversity of wild things that call our nature preserve home, and try as best we can to foster an appreciation for that wildlife among the people who visit the nature center and preserve. And also an appreciation for the good that being out and a part of nature does for them both physically and emotionally. Caring for nature is not a one-way street.  Just like the benefits we reap when we care for and are kind to each other, we are the better for caring for the wild things which share the world with us. Unless of course they are the invasive kind which bully their fellow animals and plants.

Rusty-patched bumble bee on culver’s-root at UW–Madison Arboretum. Photo: Susan Day/UW–Madison Arboretum

Each year it seems that there are more opportunities to survey wildlife. Citizen-science is a growing field in which people who aren’t professional scientists with an academic specialty can still contribute wildlife observations in a meaningful way, especially with a little training. Our staff falls into that category as we survey birds, bats, bumblebees, and other wildlife.  We are knowledgeable people, but not experts in any one field. Fortunately, because Woodland Dunes is a special place in terms of wildlife habitat, we are visited by people who truly are experts in their fields, and those visits often reinforce the importance of what we do.

Two such visits happened recently in late summer. The first involved a brief survey conducted by an entomologist from the Wisconsin DNR, who visited some of the meadows here to look for bumblebees. In all, he found eight species – including one federally endangered, the rusty-patched bumblebee.  The rusty-patched is a formerly common bee species, and we’re in the middle of it’s range. Unfortunately, due to a number of factors brought on by changes in habitat and others, this bumblebee has declined significantly, nearly to the point of non-existence. In the last several years, however, this species has been found in two different locations on the Woodland Dunes preserve in areas where native wildflowers and grasses have been planted.

A few weeks ago, we were informed by a botanist working for a consultant on one of our habitat restoration projects that he had noticed a small wildflower blooming near one of the wooded trails – a forked aster.  Most people wouldn’t think twice about this low-growing plant blooming in September in the woods, with it’s loose daisy-like lavender blooms, but to those who are familiar realize it is a threatened plant in Wisconsin.  It is found in forests dominated by hardwood trees, often on the shores of lake or streams. It is often found near oaks, boxelder, ash, and popple trees.photo of forked-aster

These two species are important to us in a number of ways. They are among the last of their kind – that in itself makes them special. They represent the wildness that Woodland Dunes hopes to preserve, and the fact that they have found this place underscores the value of high-quality natural areas as refuges for life that faces so many challenges in places that have been unthinkingly disturbed or damaged.  So, when you visit Woodland Dunes, it might give your visit added meaning to know that these little plants and animals which are so easily overlooked are here and hanging on to life along with hundreds of others which share this very special place.

photos- rusty-patched bumblebee from US Fish and Wildlife Service, forked aster at Woodland Dunes by Joshua Sulman

Ripples 10/16/20

Written by Jessica Johnsrud, Education Coordinator

Earlier this summer, I had the pleasure of leading a family twilight program. Two families participated in the program and it was the first time most of them had walked a trail in the dark, including the parents.
 
After a brief introduction, we started down the trail. The kids were buzzing with excitement and perhaps a little nervousness too. Any nearby animals were surely alerted to our presence. However, after a few minutes, everyone quieted down and started using their senses to take in the evening.
 
We stopped in the prairie and listened with our “deer ears,” by cupping our hands behind our ears. The kids were able to pick up faint cricket sounds as well as soft call notes of songbirds they weren’t able to hear before.
 
Being in an open space, our eyes naturally gravitated to the evening sky. One of the older boys found the Big Dipper and proudly pointed it out to the rest of the group. We stood for a few minutes, in awe of the great number of stars we could see. One child noted he doesn’t see as many stars at his house in town. One of the youngest boys and I both had the good fortune of seeing a shooting star. He was very excited because it was the first one he had seen.
 
We then turned down the trail and headed back in the woods. We noted how dark it was and how difficult it was to see anything, except for outlines of the trees. As we slowly walked along, feeling the ground through our shoes, one of the kids saw something glowing along the side of the trail. We all stopped to watch, and sure enough, there was something small, glowing in the plants.
 
Once everyone had a good look, I used a small flashlight to investigate. To my delight, it was a firefly larva! I gently picked it up and showed everyone the strange, armored-looking creature. I explained firefly eggs hatch into larva that live in the ground. They are carnivores, eating snails, worms and other small invertebrates. Adult fireflies are famous for their spectacular light shows, but the eggs and larva of some species also glow. This is possible through a chemical reaction called bioluminescence. I set the firefly larva back where it was found and as we continued on, we saw dozens of them scattered on the ground! What a treat!
 
Back at the Nature Center, I asked everyone to share something they learned or share their favorite part of the program. One child said, “I never knew firefly babies could glow!” Other highlights mentioned were the shooting star, the bright starry sky and the chance for each child to briefly lead the group in the dark. It was a night of many firsts and something I think we will all remember for quite some time. 


Ripples 10/8/20

As October wanes, animals are faced with several choices.  Well, not really choices, because they are determined by biology photo of common eastern bumblebeehoned over millions of years.  
 
There are two types of dormancy in living things- prescriptive, in which an organism enters dormancy before conditions become too difficult for survival, and consequential, in which an organism enters dormancy after conditions become too difficult to survive under normal means.
 
On the asters along our driveway, some of the last blooms of the season, a few worker bumblebees forage on sunny days, along with some gynes, next year’s queens.  The worker’s days are few now- they won’t survive the winter.  The gynes, however, go through diapause, during which their life cycles are suspended. They will spend winter in an old rodent burrow waiting for spring.
 
There are fewer and fewer frogs now, where once they had been so abundant.  In the parking lot, a snapping turtle crawls determinedly toward a pond.  Both are seeking a place to undergo brumation, during which reptiles and amphibians experience lower body temperatures either on land or in the water.  Some frogs, such as tree frogs, wood frogs, chorus frogs, and spring peepers, either freeze or nearly freeze, their cells protected from bursting by glycogen which they draw from their livers.
 
Some animals hibernate, lowering their normally warm body temperature to temperatures which allow them to burn less fat and sleep right through winter. Bears and ground squirrels are hibernators. Others partially hibernate – lowering body temperature but still eating occasionally, like chipmunks.  Even feisty little chickadees and other birds can lower their body temperatures at night and shiver throughout the day and night when it gets cold.  
 
Trees become dormant, although that is as much caused by the desiccation of dry winter air as it is from the cold.  
 
In addition to plants, other organisms such as bacteria and viruses have their own ways of going dormant- actually sometimes viruses cause bacteria to become dormant.
So creatures of all sizes have widely different methods for coping with the oncoming season.  That they are so different is remarkable and is a testament to their abilities to adapt to the many different scenarios which they must face.

 

photo- wikimedia

Ripples 10/1/20

October.  The world is suddenly cool and colorful.  And alive with birds from the north passing through,  insects galore, and bursts of new wildflower blooms.  

I stole away one morning last week to walk a short loop on Willow Trail, one of the best areas in our preserve for migrating photo of wooly aphids on alder songbirds, to see what the previous night brought us. It was a partly cloudy and breezy day, but not too cold. The trail was lined with white and purple asters, the dogwoods still held their now mottled leaves, and the willows and cottonwoods were as green as  summer.  The poor ash trees, however, were dropping their yellowed leaves like snow flurries- they always seem to be the first to give up in the fall.  

In the wetter areas there were alder stems of various diameters, some of which had clusters of white fuzz.  It looked like they were moldy, but in fact they were supporting colonies of wooly alder aphids- small insects which huddle together and feed on alder sap. They are present through much of summer, but when leaves begin to drop they become more obvious to the casual hiker. In fact, their contrasting color and appearance can be at first glance gross and alarming, perhaps more than they need to be.   

Wooly alder aphids are fascinating bugs.  Their “wool” is actually a waxy substance which makes them look fuzzy and actually helps them to float on the breeze when they want to move to another plant. They need two host plants- silver maples on which to lay eggs and feed, and later alders. When on alders the females pop out clones of themselves without needing any sexual means of reproduction. At a certain point, males are needed, produced, and eggs are laid in a more conventional way.  When they are stressed, such as when freezing temperatures occur, they produce winged males and females who fly to the safety of a maple tree to lay eggs.  

The aphids feed on sap, both to obtain sugars and nitrogen with which they build proteins, and alders have a special relationship with bacteria which allows them to draw nitrogen from the atmosphere. The aphids must consume a lot of sap to get enough nitrogen, so much that they excrete some of the excess sap in the form of honeydew, a mixture of sugary juice and aphid poop. Other insects like ants feed on the honeydew and actually shepherd the aphids in little wooly flocks on the alders.  

The adult aphids probably die during the winter, but their eggs survive to ensure that another generation of wooly aphids, or fairy flies or fluff bugs as they’re sometimes called, will intrigue us next year. It’s almost guaranteed, as one researcher estimated, that if there were no predation or disturbance, a female could produce 6 billion offspring during the course of a year! There is predation to keep the aphid numbers under control, and they don’t do permanent damage to the trees.

Sometimes the smallest creatures are some of the most interesting, even if they are very different from us.

Photo – wooly aphids on an alder by Jim Knickelbine