In a Field of Goldenrod

Kids and naturalists wielding bug nets ventured into the tangled vegetation. Sweeping the nets from side to side among the grasses and flowers, these budding entomologists soon discovered the diversity of life hiding in an overgrown field.

Plumes of yellow goldenrod flowers danced in the breeze next to succulent stalks of common milkweed, and insects buzzed in the warm sunshine. While goldenrod flowers get a bad reputation for being the cause of summer allergies, their heavy pollen grains do not drift through the air and into our nostrils. The brilliant yellow heads composed of many tiny florets and the leafy green stalks provide food and shelter for a myriad of insects, and insects were what we were hoping to find.

My first catch, since I was one of the participating “kids” on this bug collecting expedition, was a beautiful grasshopper with red hind legs. Appropriately named the red-legged grasshopper, Melanoplus femurrubrum (from femur=thigh, rubrum=red), it is one of the most common grasshoppers in North America, with the center of its population directly over the Midwest.

Red-legged grasshoppers have good nutrition down pat, eating a variety of plant species in a single meal. Those fed on just one type of plant, even if it is the seemingly nutritious alfalfa, developed health issues and produced fewer eggs. The way they eat is interesting, too. The poet Mary Oliver observed a grasshopper “the one who is eating sugar out of my hand, who is moving her jaws back and forth instead of up and down,” and described it in her poem “The Summer Day.” It is from that poem that I learned that grasshoppers do indeed move their jaws back and forth to chew!

The chewing action of the goldenrod gall fly, Eurosta solidaginis, does more than just facilitate eating. After a female gall fly deposits an egg into the stem of a goldenrod plant, the egg hatches in about ten days, and the larva immediately starts eating the stem from the inside out. The chewing action and the larva’s saliva, which is thought to mimic plant hormones, cause the goldenrod’s stem to thicken into a dense, round gall.

Sliding my bug net over the top of a goldenrod flower, I caught a beautiful orange-belted bumblebee, Bombus ternarius. I was glad to have a closer look, because I’d seen several on prairie blazing star (pretty purple flowers) at the Forest Lodge Nature Trail recently, and wondered what they were. These smaller bees tend to forage at the tips of the goldenrod flower clusters, while letting bigger bees occupy the cluster’s center.

Looking closely at the center of a goldenrod flower cluster, I notice a deviation in the pattern of blossoms. As I peered closer, the smooth round body and eight legs of a goldenrod crap spider came into focus. This tiny hunting spider has a short, broad abdomen, and legs that are held outstretched to the side that enable it to move sideways, forward and back just like a crab.

Goldenrod flowers are a great spot for this spider to wait in ambush for bees, wasps, butterflies, moths and other nectar-seeking insects. To camouflage itself from the eyes of both predators and prey, crab spiders can change from the yellow to white, depending on the color of the flower they live on.

Some consider goldenrod a weed, while others plant it in their gardens. When sorting and identifying the diversity of insects trapped by our nets, it is evident that no matter what we think, many insects like goldenrod just fine.

And, just for the record, it is ragweed—not goldenrod—that makes you sneeze.

Bluegills!

Thunder rumbled in the distance as the setting sun illuminated cumulonimbus clouds towering above the lakeshore. My parents and I paddled our canoe slowly around the weed beds on the perimeter of the lake, “heading in” we called it, while still casting leisurely among the water lilies and rushes. We already had about eight hand-sized bluegills on a stringer. None were trophies, but all would be tasty fillets.

As the old concrete boat ramp appeared through the weeds, I made one last cast. Plunk! My bobber dropped just this side of a half-sunken log. With a click and whirr I began reeling in my line. Not two feet from the log, I had a hit! I set the hook and reeled quickly, surprised at the fight on the other end. “It must be a bass,” I exclaimed, until I saw the big roundish body and bright yellow belly come to the surface. This female bluegill was a very respectable nine-inches or so. She went on the stringer as we drifted into the landing. It was the perfect end to an evening on the water.

Panfish, including bluegills, crappies, and perch, are Wisconsinites’ favorite fish to catch. Kids, and kids-at-heart, get an easy thrill when the bobber dives under and the fight begins. Even catching the fingerlings is fun, and jokes about the “biggest fish of the day,” never seem to grow old.

The Museum recently hosted a lecture about bluegills by Dave Neuswanger, fisheries biologist for the DNR. He has been putting together a literature review of scientific papers written about bluegills. Of course, he is gathering the information for use it in fisheries management, but he uncovered some strange facts about these common fish, too.

Did you know that their scientific name, Lepomis macrochirus, means “large hand,” and refers to their relatively large pectoral fin? Male bluegills also have a large earflap and orange-to-coppery breast, while the females have a normal-size earflap and a bright yellow breast. Bluegills do hybridize with their cousins the pumpkinseeds, but it only works with a male bluegill and a female pumpkinseed, not the other way around.

Male bluegills build their nests by swishing and scooping fine sediments out from around bigger stones. Bluegills prefer gravel to sand or muck, but they will make do with many types of substrates. Larger spaces between the pieces of gravel allow fresh water and oxygen to flow among the eggs, and help protect the eggs from predators.

Dozens of males build their nests in a cluster. Nests on the inside of a colony tend to be more successful than nests on the perimeter. Males must defend the nest from snails, crayfish, black bullheads, and even other bluegills! Younger, smaller bluegills are a significant source of mortality for bluegill larvae after they leave the nest. That’s not the only weird nesting behavior they have, either!

Males build and defend a nest, and females come to them. The pair will swim side-by-side in a circle-dance, each emitting their own reproductive products. One female may visit 2-3 different nests to lay all her eggs. Sometimes a precocious male, who is younger but matured faster, will hover around the nest and change colors to closely match the female already engaged in mating. Then he will join the mating dance! The parental male who built the nest will think he’s got two girls, when really the younger male is fertilizing some of the eggs. Other times, precocious males called “sneakers” will just dart in and give a good squirt, fertilizing as many eggs as they can on short notice!

No matter how they do it, I am grateful that bluegills have plenty of babies. That means there are more for you and me to catch and eat!

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013. Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/

Blackberry Receptacles

Reaching through the thorny bramble, my fingers closed on the biggest, juiciest, blackberry I had ever seen. My pail was over half full, but this berry did not join the crowd, instead I popped it straight into my mouth. Sweet juice burst into every corner of my mouth. Yum!  I love berry season!

Berry season is a time for red fingers and purple tongues.  Not just blackberries, but raspberries, serviceberries, and blueberries all contain a pigment called anthocyanin, which can be red, purple, or blue depending on the acidity of the fruit.  In nature, pigments do not just provide color; they also carry out important functions.   Anthocyanin is useful to plants as a sunscreen, and to us as an antioxidant. 

In fact, blackberries’ antioxidant capacity ranks near the top of 1000 antioxidant foods consumed in the United States. They are also notable for their high nutritional contents of dietary fiber, vitamin C, vitamin K, folic acid (a B vitamin), and the essential mineral manganese. Blackberries even retain most of these health benefits through the process of making them into jam and storing them over the winter.

As my pail filled with blackberries (the goal of the day), my mouth often filled with red raspberries, too. These close cousins share the genus Rubus in the Rose Family. Have you ever noticed that when you pluck a raspberry off the plant, there is a little white dome left behind? The matching recess in the berry itself is the perfect size for capping little fingertips, or hiding sneaky bugs. Blackberries do not have that.  Their base is flat, and they pluck cleanly off the stem. There is a botanical reason for this.

Raspberries and blackberries begin with very similar flowers. They both have five white petals that surround an outer ring of many stamens (the pollen-producing part) and an inner cluster of pistils (the female part). All these parts are joined at the base in a structure that botanists call the hypanthium. The hypanthium, in turn, is attached to a flower stalk called the receptacle.

As a pollen grain lands on one of the many stigmas (the tip of the pistil), it travels down a pollen tube to fertilize the ovule (egg) in the ovary. The fertilized ovule becomes the seed, and the ovary develops into the juicy fruit. On raspberries, the top parts of the pistils remain as tiny hairs bristling out of each bump on the fruit.

Have you ever noticed how hard blackberry seeds are when they get stuck in your teeth? Each tiny seed is enclosed in a lignified (woody) case – just like the pit of a peach. The term for this type of a fruit is a “drupe.” Cherries are another good example of drupes.

As the many pistils in raspberry or blackberry flowers receive pollen, each ovary develops into a little drupe or “drupelet.”  The drupelets then fuse together into the many-dimpled raspberry we know and love. Thus, blackberries and raspberries are not berries at all, but “aggregates of drupelets.” True berries are simple (not aggregate) fruits that develop from a single ovary. Some examples of berries include avocados, bananas, blueberries, grapes, tomatoes, watermelons, and pumpkins.

The main difference between the two fruits I encountered in the thorny bramble is that in addition to fusing all the little drupes together, blackberries incorporate the receptacle (the base of the flower) into the fruit, while raspberries leave their little white cone of a receptacle still attached to the plant.

While botany fascinates me, at the end of the day, the only receptacles that I pay attention to are the full pail and my happy belly!

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013. Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/

 

Last Summer Song

The half-mile bike ride to my garden is a pleasure in both the early morning and early evening. Soft light illuminates fluffy clouds, cool breezes bring relief from the heat of the day, and the ethereal song of the Hermit Thrush drifts through the quiet forest. Most birds are done singing for the year, their chicks are fledged and males no longer need to defend a territory or attract a mate. The cacophony of early summer is replaced by a few vocal marathoners.

Hermit Thrushes are one of the earliest birds to return to the Northwoods, and their beautiful song is a welcome contrast to the gray days of late March. With almost equal vigor, they continue to serenade us throughout the summer. You may have listened as one began its song with a thin whistle, and followed with a flutey jumble of notes. The flutey quality, and often the impression of a duet, comes from the thrush’s elaborate sound system.

Amphibians, reptiles, and mammals (including humans) sing using a larynx. We generate sound by forcing air through the trachea, causing thin membranes to vibrate. Our larynxes only use about 2% of the air we exhale. Birds, in contrast, have a syrinx. This set of membranes restricts the airflow through the trachea, right where it splits into the two bronchial tubes.

The syrinx is much more efficient than our larynx, and can turn almost all of the passing air into sound. This is why tiny birds can make gigantic sounds! With the syrinx straddling two separate tubes, each with separate sound-producing membranes, control muscles, and neural connections, thrushes and other birds can produce two sounds at once. Songbirds (including thrushes), can even do their own version of circular breathing by singing out of one side of the syrinx while inhaling quick breaths through the other side.

Not all birds have the same sound system. Both the structure of the syrinx and the training to use it can differ. Thrushes and some other “oscine” (from the Latin word “to sing”) songbirds need to learn their songs. In the “suboscine” group that includes flycatchers and Eastern Phoebes, songs are innate. Other birds, like vultures, can hardly make sounds at all.

Many herons only make harsh squawks, but the American Bittern makes a loud, guttural, booming, "oog-ka-chuk.” Males fill their gullets with air and then release it through a specialized esophagus. The bittern’s unique call has led to many other common names, including water-belcher, mire drum, and thunder pumper.

The low sound travels well in the evening air of wetlands, and can be heard at a distance of several miles. This enables scientists to count several types of marsh birds using song surveys.

Visual surveys of the bittern would be difficult. Long brown and white vertical stripes on their bellies provide them with excellent camouflage in tall marsh grasses, and they even sway with the wind to make their disguise complete. The several I have seen have been spooked into flight by plant biologists slogging through wetlands that rarely have human visitors.

Unlike thrushes, bitterns only sing during mating season in the spring. That is why I felt very fortunate on a recent evening to see two bitterns in a friend’s bur oak tree, where they looked awkwardly out of place as they went mutely about their insect catching.

The silence of summer adds to birds’ camouflage as they raise their fledglings and molt feathers. The birds that do keep singing, like the Hermit Thrush, may be conducting singing lessons with their young. Remember, they are oscine songbirds who must learn the proper melody for their species.

Both Hermit Thrushes and American Bitterns will soon be preparing for migration, and the woods will be still quieter. I may have already heard the last thrush concert for this year. Luckily, we have several hardy birds that stay throughout the year, and the cheerful calls of chickadees and nuthatches will keep me and the garden company through the winter.

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013. Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/