Lake and Wetland Ecosystems

What is Detritus?

Posted on January 30, 2015 by Andrew Sabai

Leaf Litter from previous growing seasons is the main source of detritus for this sedge meadow.

Detritus is debris or waste of any kind. When we think specifically of detritus in lakes and wetlands we think of the undecayed organic matter of plants and animals. It is this that is typically the main source of nutrients in a body of water. The source of detritus can be organisms the grew within the lake, or those that came outside it.

Outside sources of Detritus

Erosion can bring in all kinds of organic matter, usually from plants. Depending on the location of a body of water or wetland the main source can be quite variable. In a river with a large floodplain the main source may come from when the river overflows its banks and picks up organic matter from flooded wetlands, farm fields and woodlands.

A small lake, or rivers big and small in a forested setting may get most of their nutrient inputs as leaf fall. The leaves of overhanging trees land in the water, sink and aquatic organisms begin to break them down. First come the “shredder” invertebrates. These are able to shred tough leaves into smaller pieces that they eat, or the scraps are eaten by others. Then an assortment of other invertebrates continues to eat the smaller sized pieces, or the microorganisms that further break them down. Without this source of nutrients many streams would be sterile.

Detritus at the edge of Emmons Creek in February consists of fallen leaves, and emergent plants growing along the bank.

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Posted in Definitions | Tagged Detritus, nutrients, Streams, wetlands | Comments Off

West Bay Cane Bed Flight

Posted on January 23, 2015 by Andrew Sabai

The West Bay Cane Beds in Lake Poygan have been in decline for decades, but the last decade has been particularly unkind. The beds are rapidly eroding from wave and ice action. The beds are now so small that a hand full of muskrat families are eating much of what remains.

I flew a small drone over the vegetation to document its current sad condition and to compare with some past air photos.

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Posted in Conservation | Tagged Cane Beds, Lake Poygan, Video | Comments Off

What is a Forb?

Posted on January 14, 2015 by Andrew Sabai

A Forb is a herbaceous or non-woody plant that is not a grass, sedge, or rush (graminoids), so practically all wildflowers fall into that category. “Wildflower” is a loose term in itself and could be said to include roses, which are a woody plant. Sometimes we throw terms around without even thinking, and eventually, they come to mean multiple things, or the definition becomes fuzzy. Hopefully, this little post clears up the definition.

Forbs such as goldenrods, thistles are surrounded by Tussock sedge (Carex stricta), a non-forb.

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Mouse Tunnels in the Snow

Posted on January 7, 2015 by Andrew Sabai

Fresh tunnels in the snow, made by small mammals.

Winter finally showed up and dropped a little snow, but the temperatures fell much harder. For the last several days the temperature has dipped below freezing, so what little snow we got is going to stay with us for awhile. I had complained about the brown world last week, but now I must humbly deal with the cold. It’s not too bad without the wind, but lately its has dropped the temperature to twenty or more degrees below zero, with the wind chill. I ventured out yesterday, just outside of town, to feel the wind bite my face and look at the winter world. I always feel a little more alive in bitter cold, but as like having central heat to return home to.

In many places I found the tracks of small mammals, I couldn’t quite tell if they were shrews or mice. In addition to the tracks, the small furry guys make tunnels in the snow to find food and protect themselves from the cold and predators. Something that I have always found odd is that snow is an insulator. It keeps animals relatively warm compared to the outside world. It also blocks that heat robbing wind, so small animals which cool off faster due to their surface area to mass ratio, can take full advantage of the snow.

Tracks in the snow of small mammals

Snow must make it hard for mice and shrews to find food, but it also makes them less likely to become food, because the snow masks their movements. When the snow is shallow you can the surface of the snow move up, but when it is deep there is no telling by sight that a mouse is moving below the snow. The snow acts not only insulation from the cold, it dampens the sound of their movements and activities too. Still many predators have very good hearing and owls sit quietly waiting for the sound of scurrying and feeding beneath the snow. The snow makes pinpointing a target difficult for predators, but foxes, coyotes, and of course snowy owls seem to manage just fine.

The tunnels themselves are not safe havens either. Small weasels in their ermine white winter coats follow the tunnels looking for their makers. At the same time the weasels too enjoy keeping out of sight from the hawks and owls over head.

In spring, just after the snow melts you can see the remains of well used tunnels as the grass in leaves have been moved aside in seemingly random, winding patterns. The furry mammals are again exposed to the wind, rain and claws and teeth from above. I wonder if they enjoy their time under the snow, and miss it when the world thaws.

In the fresh snow I found the racks and tunnels of many small mammals. These belong either to a shrew or mouse.

Posted in Wildlife | Tagged mice, shrews, snow, tunnels | Comments Off

Rough Day on the Lake

Posted on October 20, 2014 by Andrew Sabai

It was a rough day on Lake Winnebago recently. Steady winds at 30 mph and gusts to 50 mph were driving large waves on the lake. Lake Winnebago is no pond, but it is not one of the Great Lakes or the ocean, so the waves are not monumental, but I would not want to be out in a boat on day like today. On huge bodies of water the wave heights can be immense, but on a shallow lake like Winnebago the wave lengths are short, meaning a boat, or the shore is repeatedly pounded by waves in short succession. There is no riding the waves up and down in this situations, just a constant battering. The waves are continually interacting with the bottom, disturbing the it in deeper water and churning it into a soup in the shallows.

This churning of shallow waters, and erosion of the shoreline, releases nutrients from the bottom where they can be taken up by algae. If warm, calm weather with bright sunshine were to follow a storm such as this an algae bloom would not be far behind. This time of year though an algae bloom will be less noticeable because it will be dominated by species of diatoms sometimes called the golden brown algae. When diatoms bloom they can be mistaken for sediment. In the summer Lake Winnebago would be dominated by blue-green algae.

High winds also drive water across a body of water stacking it up on one side. On October 14th when the video was taken NE winds caused a half a foot difference in lake levels according to the gauges monitored by the US Army Corps of Engineers. These changes in water levels brought on by wind events can give lake users a sense that the entire lake has rapidly changed water level, when the effect has only been local. When the wind abruptly ceases it will cause a sloshing effect, as if the lake were a huge bathtub. This sloshing is called a seiche.

Click the pdf. below and look at the bottom graph to see the differences in water levels on the four Lake Winnebago gauges

Lake Winnebago Water Levels

The above was generated by the USACE Lake Winnebago Information website.

Posted in Lake Winnebago System | Tagged Erosion, Lake Winnebago, Water Levels, Waves | Comments Off

Green Heron (Butorides virescens)

Posted on September 16, 2014 by Andrew Sabai

The Green Heron (Butorides virescens) is a small heron of about 18 inches in length with a wingspan of 26 inches. It is well camouflaged, and like all herons it often remains motionless, but when it does move it makes slow deliberate movements to avoid detection by its prey. The Green Heron eats fish, frogs, and larger invertebrates found in the shallows of lakes, rivers and marshes. Most often it catches its prey with a lunging stab of its long neck and bill. However it will also occasionally dive from a standing position.

Green Herons usually nest alone in a tree or shrub above water. However they are known to form small colonies or join the colonies of other bird species. Both parents raise the young. These birds breed primary in North American, including Mexico. Mexican birds often do not migrate. In winter most of the American birds migrate to Mexico, Central America, northern South America and the Caribbean.

A Green Heron (Butorides virescens) stalking fish on a log.

I found this young Green Heron skulking on log, on the Fox River in Green Lake County, Wisconsin. It noticed me and slowly tried to sneak away when I stopped my boat to take photographs. Peaking through the viewfinder it was hard to locate the bird at first thanks to its camouflage and slow movements. When Green Herons became alarmed, as this one eventually did, they flare a small crest and make a kuk, kuk, kuk, kuk noise, at least that is how it is described the Sibley Guide to Birds. I find Green Herons to be fascinating residents of my local lakes and marshes.

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Northern Shrike Storing Food

Posted on September 11, 2014 by Andrew Sabai

All too soon it will be the that time of year when a few hardy birds from the north come down to spend the winter in the less harsh climate of the Upper Midwest. One of those birds is the Northern Shrike (Lanius excubitor), a small bird of prey. Shrikes are well known for their method of storing food. Often the birds will catch small mammals, birds and in the summer large insects. If the shrike wants to save a meal for later it will store, or cache its prey for eating later. Many bird species like crows, ravens, and jays will do this. What makes the shrike different is it does not hide its food, rather it is stored out in the open for all to see.

Shrikes are famous for impaling their prey on the thorns of hawthorns, and other thorny trees and shrubs. There are a few of those in the marsh I was walking through, however there were plenty of cattails. This shrike, or shrikes tightly wedged their food between the stem and leaf of cattail plants. All the food I found stored in this manner were shrews, which are tiny predators themselves. Shrews mainly eat insects and other invertebrates, but can take down mice with the help of their poisonous saliva.

Shrikes are famous for storing their food by spearing it on the long thorns of some trees and shrubs. At least on Northern Shrike (Lanius excubitor) in this area has found that cattails (Typha sp.) make a good place to store food. While walking through this wetland one winter I notice three shrews, like this northern short-tailed shrew (Blarina brevicauda) stuffed between the cattail’s stem and leaves.

The day I took the above photo I found about half a dozen stored shrews, and no other animals stored on cattails. I was far from shrubs or other places that could be used for storage, and unfortunately the marsh was largely covered with invasive hybrid cattails (Typha x glauca), but the shrikes took advantage of what they had. I wonder if these shrews had been caught in the marsh, or the shrub carr habitat nearby. In the marsh I found no tracks or tunnels of any small mammals and I don’t know if they are inhabited by them at anytime of year. If the shrike did fly the shrews all the way over to this part of the marsh it must have been to avoid having another predator or scavenger find its food.

Posted in Birds | Tagged Cache, Northern Shrike, Shrew | Comments Off

Looking for Wild Rice on the Rat River.

Posted on September 9, 2014 by Andrew Sabai

Today I took a little trip on lakes Poygan and Winneconne looking for Wild Rice. I was curious to see how it was faring this year, and also looking for a bit to harvest. Formally these two lakes, especially Lake Poygan, were rice lakes; meaning a great potion of their surface area was covered with wild rice. In the 1800’s there would have been thousands of acres, today I can say there were a couple of acres, if I am generous. The most wild rice occurred in Boom Bay, which is located by the inlet of Wolf River. Much of the rice was short, but there were several tall, dense stands. Although there wasn’t a lot of rice there were red-winded black birds and wood and mallard ducks enjoying what was there.

Red-Winged Blackbirds on Wild Rice

As I approached the blackbirds on the rice bed, they refused to leave. I wonder if they were so full of rice they did not want to fly. In fact they barely moved at all, and made no calls. Now that I think about it, I wonder if they are ok. I’m sure they just had stuffed bellies from feasting. They looked as lethargic as I do after a Thanks’ Giving dinner.

Finding only a few scattered beds of wild rice on the lakes, I decided to head up the Wolf River to check out a few sloughs. None of the sloughs had much rice in them, so I ventured up the Rat River. I have spent a fair amount of time in the marshes and swamps of the Rat River State Wildlife Area, but I haven’t actually spent anytime on the river, so it was about time I explored the river.

I engaged my outboard motor and began my way up the river. The Rat is a slow river, and looks great to canoe of kayak on, and I plan on returning with my canoe someday. However, today I had my work/fishing boat, and I enjoyed the travel too. I found a few small beds of wild rice, but after traveling a couple of miles of river they didn’t even add up to be half an acre.

Although low on rice, the river was clear and full of other aquatic plants. Waving in the current were: Coontail, Eurasian Water-milfoil, and Water Stargrass to name a few. I eventually had to give up my travels when it got too shallow to proceed, which happened to be the first bridge to cross the river at South Road.

It is a shame that nearly all the wild rice is gone from the system. It once supported vast quantities of migrating waterfowl and even passenger pigeons now then. It would have also supported many small fish, invertebrates and other creatures. Today we have only a few beds to remind us of once was, but at least we have those.

End of the road at a bridge crossing the Rat River

Posted in Lake Winnebago System | Tagged Rat River, Wild Rice | Comments Off

Boardwalk Through Wetlands

Posted on September 5, 2014 by Andrew Sabai

Boardwalk through a tamarack swamp in northern Wisconsin

Wetlands can be difficult to travel in. Wet, soggy ground require proper footwear in order to stay dry. Rubber boots are great in a wetland, or on dewy ground, but on a long hike they quickly become hot, sweaty and uncomfortable. The soggy ground can also suck feet in making your movements tedious and arduous. Wetlands however are great places to explore. Many unique plants and animals reside in marshes and swamps and nowhere else. Even more common species often use wetlands for feeding or taking shelter, not to mention some require them, if only briefly, to complete their life-cycle.

Sometimes elaborate boardwalks with bridges and lookout towers and decks are put up to allow nature lovers better access, but sometimes all that is needed are a few simple boards. I was up in the Nicholet-Chewamegon National Forest recently and came to this short boardwalk that cuts across a tamarack bog. It is utilitarian, designed only to get the hiker over the wetland while staying dry. However short, it allows great access to a moss covered world under the feathery soft needles of tamarack trees. I paused to take photos of many kinds of plants, cranberries, Indian pipe, sphagnum mosses, and to just stand in the stillness for awhile.

Panoramic view of a northern bog lake and a boardwalk that allows for easier travel for fisherman and hikers to walk to the lake.

A boardwalk destroyed by soft soil and frost heaving.

Boardwalks can be very difficult and expensive to construct. There is always the issue of the walk sinking down into the muck whether the boards are simply placed on the ground or pilings driven into it. The constant contact with water encourages rot and either wooden materials have to be replaced frequently or treated to slow the process of decay. In some climates boardwalks have to deal with heaving caused by the formation and melting of frost.

Despite the difficulties of construction and expense I hope more nature centers, parks, etc. construct these gateways into wetlands. We need more appreciation of wetlands, so people will fight to protect and manage these wonderful places.

Posted in Uncategorized | Tagged Boardwalk, Hiking, Wetland | Comments Off

Foggy Lake Morning: Photo of the Week

Posted on August 9, 2014 by Andrew Sabai

A peaceful and quiet, except for bird song, morning on a small Wisconsin lake in Forest County. Getting up early often pays dividends in getting good photos and seeing wary wildlife. On this morning I was certainly not up early, but at a reasonable hour, early enough to catch the fog before the sun burned it off.

Misty summer morning on a Northern Wisconsin Lake.

Posted in Photo of the Week | Tagged Lakes, Photo of the Week, Photography, Wisconsin | 1 Comment