Marshes, mink and muskrats

MARSHES have a long love/hate relationship with people in America. Thankfully we’ve almost made a full circle of attitudes concerning these special land forms. Once despised as impediments to a young and growing nation, wetlands were drained, ditched, and developed. It took a long long time for the consequences of the former attitude to find recognition for a large array of benefits to society from healthy wetlands and marshes. And we still live with both the positive and negative effects of short-sighted federal and state policy concerning wetlands. But what is past is history. Can we learn from those lessons of what to do now and what not to do? Time will tell.

Across the landscape of Iowa’s total of 56,272.81 square miles, land made up 99.26 percent of this or 55,857.13 square miles. Subtract the two and what is left are water equal to 414.68 square miles or 0.74 percent. Water areas were and still are the border rivers of the Missouri and Mississippi, plus all our internal river systems, natural glacier carved lakes, and a sprinkling of man-made lakes, ponds anywhere the landform could allow for their construction.

At the time of Iowa’s settlement from the mid-1800s, it is estimated that the lands of the Hawkeye State were 85 percent tall grass prairie, 13 percent forest and 2 percent water. A large portion of those water areas at that time were upland depressions of all sizes and shapes, the footprints of past glaciers and especially the last glacial system, the Wisconsinan. As retreating ice margins laid bare the land, water filled any shallow, moderate or deep depression. Uplands surrounding these water sites grew the grasses native to the entire Midwest region. National estimates looking back to the early 1600s for the conterminous United States places wetland acreage at 221 million acres. By the mid-1980s, 103 million remained. Six states had lost 85 percent or more of their original wetlands, Iowa being one of those.

A historical perspective is in order to see how attitudes and opinions have changed and how we now know a lot more about the ecological value to fish, wildlife and the environment as a whole. Our present day conversation about improving water quality comes from observing issues that are not easy to fix. I’ll have more on this later.

During the 1700s, wetlands were regarded as swampy lands that bred diseases, restricted overland travel, impeded the production of food and fiber and were generally not thought of as useful for frontier survival. Pioneer hunters however had a sense of wetland values even if their benefits could not be articulated. Waterfowl lived there. Ducks and geese were killed and eaten, and used without limit.

When it came time to farm the land, wetlands were seen as roadblocks. Technical advances in machinery in the late 1800s provided methods to use steam-powered dredges to drain large wet areas, clear bottomland timber and make new areas available for farming. Federal policy encouraged wetland drainage with the 1849 Swamp Lands Act, later amended in 1850 to cover 12 states. Reclamation projects blossomed. Railroads were moving west. It took fuel (wood) to burn in the locomotives and so began a long march across America to build railroads. In 1860, more than 30,000 miles of rail track existed in the United States. Just in Ohio railroads consumed 1 million cords of wood annually just for fuel. Railroad ties under those steel tracks was another huge user for wood, the amount unknown.

Ohio once had a huge wetland/swamp in its northwest corner that was a barrier to travel and settlement. It was 120 miles long and 40 miles wide. The Black Swamp was an elm-ash forested wetland that held commercially valuable trees. By the end of the nineteenth century, it was all gone. Likewise in Minnesota, Iowa, the Dakotas, and the bottomlands of Arkansas and Missouri, and the delta lands of Mississippi and Louisiana to the gulf plains of Texas, one factor in westward expansion had to deal with wetlands. The smallest wetlands were easiest to deal with. They went dry first. Dredges and steam shovels took the bigger problems and “solved” them with technology.

Now back to the present time. What do we know works with regard to establishing wetlands, buffer strips and allowing existing wetlands to perform their important functions. Since most wetlands are privately owned, it is also known that their protection is of public concern. That concern is and revolves around water quality issues and habitat for wildlife. And you must know this: Not all wetlands are equal nor do they contribute equally to improving water quality at the outlet.

Wetlands fall into two basic categories, riparian or interstream divide wetlands. Riparian wetlands are normally low, narrow and exist along the margin edges of streams. They tend to be wet most of the time due to surface and subsurface water flows. Soil types are alluvial meaning water deposited. Other wetlands on upland divides are not alluvial but do originate from poor drainage in flat areas where rainfall exceeds evaporation or transpiration from plant leaves. Each wetland type makes different contributions to water quality. Natural vegetation in any wetland also is a factor whether forested, shrubby or cattail marsh.

Wetlands work this way. First runoff water at the surface enters a basin and slows down or ponds. Subsurface water slowly but steadily soaks through soil layers and also enters the basin or ponded site. Next, the basin and its vegetation filter contaminants out. Eventually cleaner water exits the pond at the surface. Underground seepage continues toward stream sides, again with filtered cleaner water.

How much filtering takes place? A lot. For example, runoff from agricultural fields may contain large amounts of nitrate-nitrogen and phosphorus, essential to crop growth but in high doses not so good for people. Excess nutrients entering some waters can cause algae growth increases beyond normal ranges, Researchers have studied the process on real world settings across America to see what works best for everyone. One site found the nitrate-nitrogen reduction from 15 milligrams per liter down to 2 milligrams per liter after passing through riparian wetlands. And this reduction happened after just the first 30 to 50 feet of that wetland. Wider riparian strips can be assumed to be beneficial, just like adding more filter systems to the operation. A process called denitrifcation is when soil bacteria convert nitrate-nitrogen to nitrogen gas which eventually returns to the atmosphere.

Containing or trapping soil sediments near the soil loss points of beginning is a key strategy. Keep the soil in place as best one can is the goal. Researchers found that 85 to 90 percent of sediment is deposited close to field edges. And one of the methods to trap and slow down runoff is with border strips. A well vegetated grassy or grass/brushy combo of just 13 feet made a huge difference. Wider in this case is also better. Waterway buffers and riparian buffers trap sediments, remove harmful nitrate-nitrogen, phosphorus and pesticides before they can enter streams. For all these reasons there should be a strong effort to restore wet vegetated buffers adjacent to streams.

Marshes and wetlands have a roll to play in all future water quality issues and debates. It will take everyone in the watershed, rural or urban, to contribute to solutions. In the meantime, the next time you look at a natural wetland, marsh or any buffer strips of grass along every field waterway, stream side or timbered floodplain forest lands, think of what you see as a filter. Filters take out the bad stuff and let the good stuff go through.

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MINK are one of the wildlife critter that love marshes. Why? Because that is where food can be found. These two pound predators are fearless, inquisitive, widespread and common. They are members of the weasel family that includes otters, martens, skunks, fishers, wolverines and badgers. Mink are never far from water. Mink are accurate indicators of the health of wetlands and other aquatic ecosystems. One term used is to call mink “biosentinels.” They have a low tolerance for toxins or other environmental contamination. Thus to see mink and know they are thriving is a good thing.

Mink move frequently between their watery world and terrestrial haunts. They are excellent swimmers having webbed feet. Overtaking muskrats on land or under water is easy for them. Mink also eat fish, rabbits, chipmunks, voles, salamanders and birds. They will climb trees to hunt if the need arises. Most activity is between dusk and dawn. Females raise one litter per year, perhaps three or four young.

MUSKRATS fear mink. But they make up for population losses by high birth rates. This rodent is common and is a valuable furbearer. They are dependent on water and wetland habitats of marshes, stream sides, lakes, creeks and ponds. They can tolerate a certain amount of pollution in water if not too concentrated. At 22-25 inches long including its laterally flattened tail, they tip the scales at three to four pounds. Females average bringing off 2.5 litters per year of five to six kits each time. Muskrat populations also cycle from low to high every few years. One female was recorded at producing 46 young in one year. Each gestation period is 29 days for this furry wetland dweller. Each domed lodge has underwater entrances to hollowed out places where kits are born and raised, food is stored and predators evaded. Judging from the number of lodges in Mann Marsh, 2017 is going to be a high count for muskrats.

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PHOTO CONTEST entries for the Marshall County Conservation contest are due on or before Jan. 31. Take your best images of native wildlife, scenic, native plants, or trail camera images and enter them. Deliver your entries to the MCCB office at the Conservation Center at the Grimes Farm. Awards will be publically noted at a chili supper on Feb. 7. Even if you do not enter a photo or two, you can buy tickets to eat. Then watch the show and see all the entries on display.

For details call 752-5490 during office hours.

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TAX TIME reminder to not forget making a donation to the Fish and Wildlife Check-off. Look for it usually between lines 55-59 on the 1040 form. The sum you donate will be deducted from any refund due or added to any taxes owed. What you donate is deductible next year. If every Iowan donated just one dollar to the so-called Chickadee Checkoff, it would raise an additional $1.5 million for supporting wildlife conservation in Iowa.


Garry Brandenburg is a graduate of Iowa State University with BS degree in Fish & Wildlife Biology. He is the retired director of the Marshall County Conservation Board. Contact him at P.O. Box 96, Albion, IA 50005.