Beaver business — conserve water and cut down trees
PHOTOS BY GARRY BRANDENBURG — Our modern day beaver is the largest rodent of North America. An adult may grow to a total length of 4.5 feet long, including tail and weigh up to 50 pounds. Most younger beaver and sub adults tip scales from 10 to 25 pounds. Beavers are well known for building dams across small creeks and tributaries. Thus, water is impounded behind the dam, and depending upon location, may be inconsequential or have adverse effects upon surrounding lands. In any case, this little furry engineer that Mother Nature created has claimed just about every creek and tributary. If one was to conduct an intensive survey of all the small streams of Marshall County to document beaver activity, there would be few streams left off the list. As a natural history note, fossilized skeletal remains of the Giant Beaver, which lived during the Pleistocene (roughly 2.6 million years ago up to 11,000 years ago), had a body length of about 6 to 7 feet and an estimated weight of 200 to 270 pounds. Today's image of a modern day beaver was made at a past Iowa Taxidermist Show. The cottonwood tree however was discovered recently in Marshall County. This tree did not fall to the beaver — yet — but it is severely compromised by chewing marks completely around the trunk.
Beavers are industrious, hard working nocturnal rodents that exploit just about every available aquatic habitat in their tasks of survival. Judging by the fair number of small tributary impoundments they have created via their work of stacking cut branches in a stream channel, and then packing lots of mud, stones and organic matter into a makeshift dam, we have a lot of beaver activity in Marshall County.
This largest rodent in North America is a survivor and a successful ‘engineer’ to conserve water wherever they can. Due to our drought-like low water table conditions from a long dry summer and fall, some could say the Beaver knew how to forecast the need to hold water, so they did what they could to block stream flows.
Beavers have a dense underfur and long outer guard hairs. The pelt is kept waterproof by the addition of a specialized oil produced by the animal. It will use its hind feet and claws to comb its fur and therefore always work the oil all over its soft brown coat.
Large webbed toed hind feet are tremendously useful in swimming or when walking over soft muddy ground. The head of a beaver is blunt, and its eyes are small. Its ears are also small. The neck is short and the body is stout. Short legs make the animal look somewhat awkward if observed on dry land. However, in the water, this mammal is a superb and dexterous swimmer.
Large incisor teeth are perfectly shaped to cut into the bark and internal wood of a tree. Typical tree cuts are made on those with diameters of two to five inches.
Much larger trees are also cut down just to gain access to the smaller top branches. Once on the ground, or having fallen into the water, the job of cutting off smaller branches becomes the reward for all its hard work.
Today’s image of the standing cottonwood attests to the fact that not all trees cooperate for a beaver. Most of the time a tree may lean somewhat and therefore can easily fall once enough wood is removed from the trunk, but this tree was different. It stands tall and is well balanced. The beaver tried to topple this specimen by continuing to work all around the trunk. The heartwood of the cottonwood tree remained strong. A frustrated beaver had to give up, at least for a brief time.
The tree is doomed. It has been girdled so that no nutrients can move up the tree to sustain it. It is only a matter of time, and perhaps when future strong winds hit the tree just right, or maybe a few more chewings by an industrious beaver to weaken the base a bit more have been made, the tree will fall to the ground.
When the tree is down, beaver will work diligently to eat its softer smaller branches, taking many into the water and storing them for winter food for the beaver family.
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You may not have known about another beaver from another era — the Giant Beaver from Pleistocene times. Explorers and scientists long ago marveled at the fossilized bones of extinct species that were discovered.
In a peat bog in Ohio in 1837, the articulated skeletal bones of a large animal were found. When cleaned, and reset into the living animal’s form, it was obvious by the skull, its large incisor teeth and large rear feet and toes, that this ancient animal was a beaver, a very large beaver. Scientists named it Castorides ohioensis.
This animal lived at a different time alongside other now extinct species such as the flat-headed peccary, the giant short-faced bear and the stag moose, and others. Those old bones were found in a cave in Wyandot County, Ohio. The cave name is now known as Sheriden Cave.
Fossilized bones of the giant beaver have been found in other Midwest states near the Great Lakes, in particular in Illinois and Indiana.
Other findings have been documented from Alaska to Canada and as far as South Carolina and Florida. Even New Brunswick has a specimen discovered there.
The environments across the earth were totally different during many phases of the Pleistocene. Of particular note from geologic rock records are evidence markers of at least 33 advances of northern hemispheric glacial systems during the last 2.6 million years, and in between each advance of ice, were interglacial warmer times.
This back and forth system of natural climate changes provided ample time for animals to adapt or perish. Many persisted for a long time. However, in the end, about 11,000 years ago, during the last interglacial warm period, a naturally drier and hotter environment began to dominate.
The stage was therefore set for the giant beaver and other Pleistocene animals to be gone forever. About 11,000 years ago, Paleo-Indians may have seen and interacted with giant beavers.
Speculations have been made that these peoples hunted the giant beaver and helped lead to its extinction. However, no evidence for that claim can be offered. What can be offered is that the environment was naturally changing over thousands of years from wetter and colder to warmer and drier.
Not all animal species could adapt to these imposing huge natural climatic forces. Extinction happened.
The giant beaver’s incisor teeth were huge, about six inches long. The teeth had striations on their outer enamel surfaces. It is thought that those striations added strength to the tooth.
Yes, this giant rodent could chew on trees, but this species may have dined on a higher content of aquatic vegetation. It did spend more time underwater due to its ability to hold a lot of oxygen in its huge lungs.
Paleo-chemistry tests tell of stable isotopes from plants incorporated into its teeth. To view giant beaver skeletons one can visit natural history museums in Minnesota, Wisconsin, Ohio and many others, including the Museum of Natural History in Chicago. Those bones tell fantastic stories of life long ago.
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Several hunting safety related news stories have made the news lately from across the country. Even in Iowa, incidents and accidents with firearms have injured some or been fatal to others. Looking back at the investigations made by DNR law enforcement officers, they try to find those items of inattention or reasons why the accident took place.
A review of all hunting incident/accident reports gets summarized and published for any of us who are hunter safety instructors. That way we can try to emphasize to students how firearm safety is a full time job, even when enjoying time outdoors with family and friends at a wetland waiting for ducks, or in a prairie setting after pheasants, or in a forest after deer.
Accidents happen. Unfortunately, after an incident takes place, the time to have known what went wrong is history. We can only make stronger statements about the critical nature of being totally aware of how to successfully go about any hunting experience to keep everyone safe.
In short, we have to learn from the mistakes of others, and strive to never be the person who is involved in a mishap.
During 2022, there were eight personal injuries, one property damage and five tree stand type accidents. There were no fatalities.
Target fixation is just one reason given in the incident reports. The hunter was so concentrating on taking the shot that they did not take into account things to their right and left sides, or things beyond the shot pattern in the background.
Swinging on a game bird too far and thus spreading a shot pattern into another person’s vicinity gets noted. Reckless handling of a firearm gets cited too often.
Even with nine hunting incidents during 2022, to help keep in perspective how few these are compared to the safe and correct hunting experiences of thousands of hunters across Iowa is a fact worth noting. Thousands of totally safe miles are driven by motorists each day and each year.
What makes the news? Accidents. Thousands of people fly commercially from point A to point B safely, but if there is an incident or accident, the news will jump on it.
Are we going to stop driving? No. Are we going to stop flying to visit family or friends? No. Are hunters going to stop enjoying field excursions and contribute to the conservation efforts of long term wildlife management? No. We just have to put safety on a higher level.
Firearms are mechanical devices. There is a remote possibility it could fail. A larger factor is the operator of the sporting firearms who may not know or is not constantly aware of all the safety issues with respect to its proper use.
Always treat any sporting firearm as if it is loaded, even when it is not. Be sure of your target and what is behind and beyond your target. Know where every person in the hunting group is at all times. Do wear blaze orange hunting clothing. Plan each hunt and hunt the plan, with no deviations. Prior to any hunt, do go to a range and become proficient with the limits and capabilities of both yourself and the firearm, and know when to not take a shot.
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Garry Brandenburg is the retired director of the Marshall County Conservation Board. He is a graduate of Iowa State University with a BS degree in Fish & Wildlife Biology.
Contact him at:
P.O. Box 96
Albion, IA 50005
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- PHOTOS BY GARRY BRANDENBURG — Our modern day beaver is the largest rodent of North America. An adult may grow to a total length of 4.5 feet long, including tail and weigh up to 50 pounds. Most younger beaver and sub adults tip scales from 10 to 25 pounds. Beavers are well known for building dams across small creeks and tributaries. Thus, water is impounded behind the dam, and depending upon location, may be inconsequential or have adverse effects upon surrounding lands. In any case, this little furry engineer that Mother Nature created has claimed just about every creek and tributary. If one was to conduct an intensive survey of all the small streams of Marshall County to document beaver activity, there would be few streams left off the list. As a natural history note, fossilized skeletal remains of the Giant Beaver, which lived during the Pleistocene (roughly 2.6 million years ago up to 11,000 years ago), had a body length of about 6 to 7 feet and an estimated weight of 200 to 270 pounds. Today’s image of a modern day beaver was made at a past Iowa Taxidermist Show. The cottonwood tree however was discovered recently in Marshall County. This tree did not fall to the beaver — yet — but it is severely compromised by chewing marks completely around the trunk.
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