Photos by Garry Brandenburg – Mother Nature has industrial engineers at work and on call. Where she assigns them to work on chewing trees and other wood vegetation is part of the mystery of natural history. These “engineers” are our largest rodent, the American beaver (Castor canadensis). And Green Castle became a new home for some of these animals last year. The beaver’s home means that any tree nearby is fair game that can be chewed, felled, and then cut off smaller branches to feed. The beavers have created underwater entrances to bank caves with spaces above the waterline to keep them dry. Beavers can be a nuisance is quick ordering. In the case of Green Castle, Marshall County Conservation staff had to temporarily close the park to humans in order to remove fallen trees from the beaver. Friend or foe, it all depends on the location and how their actions affect people, positively or negatively. There is no question that beavers can significantly change their environment.
THE BEER (Castdor canadensis) is an animal in our natural world that many people never see. Active at night, they can work overtime building small or medium-sized log, stick and mud dams over streams or small streams. Behind these impoundments of shallow water, an area stream can be turned into a series of small stepping stones “Mini Lakes.” And when the beaver family decides to go on a voyage of discovery, they do so for the most part invisibly and unheard of. A few days, weeks or months later, people discover that many trees have been felled or chewed through to make the tree a threat to the next wind storm. In some cases, damage to adjacent crops can become apparent.
Beavers have a stocky body with yellow-brown, thick fur. A flat and wide scaly tail is used to power others and to signal when a danger is perceived. Webbed hind legs also help when swimming. As a rodent, they have large incisors that grow continuously. Wearing is achieved daily through the action of what they eat. And when the lower and upper incisors meet, a bit of natural carving and shaping takes place to make the teeth work like perfect chisels.
The rear feet of the beavers have a unique rear toe, the second from the inside has a double toenail. They use these feet to meticulously care for their fur in order to keep oils on the fur and prevent their fur from becoming matt. While going on land isn’t their greatest or nicest act, it’s a whole different story in the water – excellent and agile swimmers who can self propel at 6 mph. They also have large lungs that allow them to stay underwater for 15 minutes.
A face full of whiskers will help the animal recognize underwater passages or find food. His eye has a nictation membrane that closes over the eye when working underwater. It has outer ears, but valves close during underwater activity. Beaver tails are used to move in the water, to balance out of the water or as a signal of danger when they hit the tail hard against the surface of the water. Fat is stored in the tail for the winter time when food is scarce. Anatomically, the vertebrae of a beaver continue almost to the tip of the tail in the tail. The weight of an adult beaver can be 35 to 65 pounds. The heaviest beaver recorded was 110 pounds. Geologically speaking, giant beavers were part of the landscape a long time ago. These extinct beavers were huge. Fossil records are impressive to the giant beaver. Our common beaver’s body is 3 to 4 feet long and about 1 to 1.5 feet in height.
Dome-like lodges are common in swamp or lake habitats. A large domed hut can rise more than 6 feet above the waterline with two or more underwater entrances. The dome looks like a small island living space surrounded by water. The living quarters are in the upper center of the lodge where they can be dry. Small ventilation holes bring fresh air into the cave. Wood chips serve as litter for these creatures. Wood chips can come from any of their favorite foods … willow, poplar, poplar, aspen, birch, and maple.
Family ties are strong for beavers. As social animals, each group consists of a breeding pair, the young animals and the surviving offspring from the previous year. It is believed that the dominant pair of beavers are lifelong partners. Mating takes place from January to February. Kits are born in spring and weigh about 1 pound, are covered in fur, and their eyes are open. The boys stay in the family unit for two years and learn how to find food, maintain the lodge and help raise younger siblings.
Skilled trappers trying to remove beavers from areas where they are causing problems will have to cut out their work for them. Just taking a beaver or two won’t solve the problem. Removing the whole family is the goal, but a goal that is very difficult to achieve. Catching beavers requires skills to set the correct rigging and requires long hours of work before, during, and after.
Fishermen and women in the region have been on the coast of Green Castle since mid-March. Evidence of beaver action was not difficult to find. Many trees were damaged. MCCB staff removed these trees. However, this spring, more trees fell victim to beaver energy. Trees that have been significantly felled or weakened are easy to spot. It is true that the Green Castle beavers modify the location so that it adapts itself without regard to our human endeavors. Learning to live with beavers will be an ongoing fact of life. These great rodent engineers are likely to win their game.
During the past week, once hard-to-find PHEASANTS seem to be more common. Crowing rooster pheasants have made their cackling clear. Even if I can’t see them, I heard them. And that’s good. Then in some of the strangest places a rooster and chicken pheasant broke out of a grassy ditch by the roadside and flew safely across the pavement to avoid the windshield and grill of my vehicle. A relatively dry spring is good news for chicken pheasant nesting. Soft rains are welcomed by all wildlife and farmers in the region. Gully washing machine doesn’t rain that much. We can only ask Mother Nature to be gentle with her rainwater from the sky in May.
MAY is our new month. The day length for us who live at 42 degrees north latitude is 14 hours and 5 minutes on Sunday. Until May 31st, the day will be 15 hours long. Those long days with long hours of sunshine will be magical for all things growing green. Photosynthesis, the process of sun exposure to leaf chlorophyll, creates sugar for all plants.
Even in May, get ready to fish for walleye in the Iowa Great Lakes. This fishing season started on Saturday. Bluebirds hatch their first of two broods on or around mid-May. Bobolinks who spent their winter in Argentina should also return in mid-May. Pheasant hatches can begin on or around May 19th, weather permitting. On May 26th there will be a total lunar eclipse with no cloud cover for us humans to observe. Finally, on May 28, 1947, the northwest two-thirds of Iowa received 10 inches of snow from the long-ago weather reports. Put that in your trivia memory bank.
Here is my parting thought for you to think about. In the face of the eternity of time that has gone before us and the eternity of time that will follow our death, notice these words of the Blackfoot Indians. “What is life? It is the lightning of a firefly in the night. It is the breath of a buffalo in winter. It is the little shadow that runs over the grass and is lost in the sunset.”
Garry Brandenburg is the retired director of the Marshall County Conservation Board. He is a graduate of Iowa State University with a BS in Fish and Wildlife Biology.
Contact him at:
P.O. Box 96
Albion, IA 50005
Photos by Garry Brandenburg – Mother Nature has industrial engineers at work and on call. Where she assigns them to work on chewing trees and other wood vegetation is part of the mystery of natural history. These “engineers” are our largest rodent, the American beaver (Castor canadensis). And Green Castle became a new home for some of these animals last year. The beaver’s home means that any tree nearby is fair game that can be chewed, felled, and then cut off smaller branches to feed. The beavers have created underwater entrances to bank caves with spaces above the waterline to keep them dry. Beavers can be a nuisance is quick ordering. In the case of Green Castle, Marshall County Conservation staff had to temporarily close the park to humans in order to remove fallen trees from the beaver. Friend or foe, it all depends on the location and how their actions affect people, positively or negatively. There is no question that beavers can significantly change their environment.
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