RiparianRiparian Zone Retreat Zone Retreatand population studyand population study

Cole BridgeCole BridgeHonors Biology IIHonors Biology II

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Muskrat Ondatra zibethicus

The muskrat is a very large rodent that lives near water. It has a brown, fury coat with a scaly tail. Muskrats can grow up to two feet long, including the tail and their rear feet are webbed and designed for swimming. They have very small eyes and ears. Muskrats live in ponds, marshes, rivers, streams and lakes and can often be spotted on grassy banks.

Factors which Affect Birth Rate of Assigned Animal

• Muskrats have a long breeding period that lasts from late winter into September. A muskrat can have up to five litters per year and have as many as 10 muskrats in each litter. The female muskrat constructs a round nest made of types of grasses to protect her litter from predators and other dangers. Baby muskrats are born without fur, but after they are around two weeks old they start developing hair and learn to swim. Usually muskrats live in large family groups, but if an older member of the group feels that the territory is becoming overpopulated they will push the younger muskrats away. Some female muskrats have been known to consume their young.

Females have such large litters because the baby muskrats are very susceptible to predators like hawks, foxes and coyotes.

Muskrats are active throughout the day and are very active in the dark. They are very good swimmers and can stay under the water in fifteen minute intervals. Their tails are fairly long and are used to help them steer while they swim. They can also eat and chew underwater.

Muskrats eat a variety of vegetable and other foods, including cattails, sedges, rushes, water lilies, pondweeds, wild rice, pickerelweed, clover, willow, acorns, maple samaras, arrowhead, sweet flag, switch grass, mussels, crayfish, frogs, snails, and fish.

Muskrats take their food to their feeding platforms. The feeding platform is often a pile of dead logs. They sometimes leave a pile of shells called a midden.When a Muskrat builds a lodge, it helps other organisms as well. Lodges can also be the home of snakes, turtles, frogs, toads, and Geese. Other animals like raccoons and opossums sometimes use abandoned muskrat holes. Muskrats eat large numbers of cattails. This opens up areas of shallow water, providing good hiding places and nest sites for water birds, and allows other water plants to grow. Muskrats have predators such as Raccoons, Red Foxes, owls, hawks, American Bald Eagles, Common Snapping Turtles, Bullfrogs, snakes, and Largemouth Bass. Other predators are cats, dogs, and people.

Producer

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Primary Consumer

herbivore

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omnivore

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carnivore

carnivore

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Producer

• Ecologists have many different ways to find out population sizes of different organisms. Depending on the organism, the ecologists use different methods. If a scientist was trying to find out how many healthy trout were in a part of a river or stream they would electroshock the water. The electricity doesn’t kill the fish, it disables one side of their vertebrae, causing them to float to the surface. The ecologists then net the fish and examine their growth and health. The fish are then released and are unharmed. For other organisms like muskrats or mammals ecologists use different methods. They consist of trapping the animals and possibly placing a monitor on them so they can keep track of them or they may just use cameras that take automatic images upon movement.

Stream Quality Data & AnalysisStream Quality Data & Analysis

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• This graph shows that Powder mill Run is a high quality stream. You can tell this because there are more class 1 organisms than class 2 or class 3 organisms. Class one organisms can only survive in healthy water with a pH around 7 and water with a high oxygen content. These organisms mainly consist of mayflies, caddis flies and stoneflies. All of these organisms indirectly affect the muskrat. Muskrats depend on trout, crayfish and larger coldwater organisms like hellgrammites. Although, all of these organisms mainly consume stoneflies, caddis flies and mayflies. Without a healthy stream like this one, the life in and around the stream would be severely restricted.

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This water testing is very typical of a healthy stream and an average marsh and mine site. For a healthy stream it should contain little to no nitrates, an oxygen level from 10 to 15, a pH from 6.5 to 7.5 and little to no phosphates. A stream like Powder mill will hold more macro invertebrates than a slightly acidic stream. A healthy stream will also maximize the life in the riparian zone around the stream that rely on the smaller organisms in the stream. It is typical of a marsh to have a higher nitrate level, less oxygen, a more basic pH and may have slightly more phosphates. A mine area will also often contain some nitrates, a low oxygen content, a more acidic pH and may contain some to very little phosphates. Out of these three locations the stream will support the widest variety of life and the strongest food web. Healthy streams create not only a variety of stream life, but a wide array of animals in the riparian zone that rely on the stream and its organisms.

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• The pH of the soil is very important for the soil to grow healthy long-lasting plants. Plants need certain amounts of Phosphorus, Nitrogen and Potassium to grow, flourish and fight off diseases. Different plants grow best in different soil Ph levels so the best Ph levels are between 4 and the neutral 7. This will allow the plants to absorb the right amounts of key nutrients. If the soil gets to be too acidic then plants can’t properly absorb the key nutrients. There should be a high potash level in the soil, which will help the plants grow well and healthy. The Nitrogen and phosphorus levels should be fairly low, usually between 2 to 4.

Positive and Negative Factors•Powder mill Run is a healthy cold-water stream that would have a positive impact on the muskrat. The muskrat would have a variety of prey due to the stable environment and large numbers of smaller organisms that the stream holds. This stream would hold enough food and healthy habitat to support the muskrat and would allow it to reproduce. The marsh and mine site on the other hand probably wouldn’t be healthy enough to support muskrats. There aren’t enough smaller organisms down the food chain that can survive in these conditions to support muskrats. A muskrat in this area would choose the stream over the marsh and mine site.

•The soil conditions at Powder mill would also positively effect the muskrat. In these soil conditions a lot of vegetation growth can occur, which will harbor more small organisms that will help link the food chain up to the muskrat. The Riparian zone also has many larger trees that prevent the sun from warming the creek above 65 degrees. If the creek would rise above this temperature, many of the organisms would start to die once it got around 70 degrees. This would inevitably make gaps in the food chain, making it hard for the muskrat to survive.

•I found it very interesting that smaller macro-invertebrates play such a large role in supporting all kinds of larger organisms that may not even live in the stream. I also thought that it was very interesting that there can be farms next to the stream, but the stream can still be healthy. I also thought it was interesting how the soil around the stream in the riparian zone can effect the plants and also the stream life, both negatively and positively depending on the nutrients and pH of the soil.

•In the future I would be interested in working in and around streams to reconstruct and help stabilize them. I really enjoyed going to Powder mill and thought the entire trip was very interesting. I would like to also learn more about factors that play a role in creating and stabilizing a healthy stream and riparian zone.

Online book

Title- Chapter 5: Life in Woodlands

Wild Animals

Date 2003

Website address- http://web.ebscohost.com

Encyclopedia

Title- Muskrat

Name of encyclopedia-Grolier

Website address- http://go.grolier.com

Date of update- 5/5/09

Website

Title- Muskrat

Name- http://www.fcps.edu

Website address:

http://animaldiversity.ummz.umich.edu/site/search?SearchableText=muskrat&category=Information&Search.x=38&Search.y=2