Tool-sharpening dam builders


A beaver swims near a tree that has been felled and flooded on Little Bordeaux Creek near Chadron.

Anyone who has watched a North American beaver (Castor canadensis) gnaw through a tree trunk has surely been in awe of its proficiency. Using teeth to whittle on wood, after all, is a task neither appealing to humans nor something the American Dental Association advises us to do.

Those four orange incisors that protrude as much as one inch from the top and bottom of a beaver’s mouth comprise just one remarkable feature of North America’s largest rodent, and perhaps its most important tool. They allow the beavers to not only cut timber for building lodges and dams, but also allow them to eat some of their favorite foods – tree bark and the thin layer of growing tissue beneath it, known as cambium.

Remarkably, the beaver’s incisors continue to grow throughout their life span, which is typically 10-15 years. In fact, the beaver’s front teeth can grow as much as four feet per year – a figure greater than its body length.

If a beaver would not chew, his teeth would surely become too long to be useful. The incisors are designed to abrade and are self-sharpening. With strong enamel in front and softer dentin in the back, they are honed to a sharp edge with each bite. A set of 16 molars distributed evenly toward the rear of their mouths complete the chewing process.

One would think the incisors might be pearly white, considering that they are constantly being replaced by new material. However, the orange coloration of the front teeth is not directly from food stains, but rather is indicative of enamel rich with iron – the same mineral that makes blood red. That iron, as opposed to the magnesium found in the enamel of most animal teeth, makes beaver teeth especially strong, hinders decay by resisting acid and bolsters strength.

The beaver is certainly worthy of awe, not only for its increasingly appreciated value to wetlands but also for its four orange tools.

In other news

Why do normally stable people go out in extremely cold weather to venture onto a frozen snow and windswept body of water to freeze their tails off and stare down through a hole in the ice to catch a fish?

LINCOLN, Neb. – The following is a listing of Nebraska Game and Parks Commission events and important dates in November. Get more event details at Visit for a list of hunter education classes and boating safety classes.

The Niobrara National Scenic River Visitor Center is welcoming children of all ages to stop by on Tuesday afternoons for Nature Creations. From 1 to 4 p.m., kids can stop by, create a craft critter and learn about how that critter spends its time along the Niobrara River.

January calendar of events

LINCOLN, Neb. – The following is a listing of Nebraska Game and Parks Commission events and important dates in November. Get more event details at Visit for a list of hunter education classes and boating safety classes.

Jan. 2, Application period begins for Super Tag and Combo multispecies lottery permits

Jan. 5, Duck and coot hunting seasons close in Zone 3, Low Plains and High Plains units

Jan. 6-27, Duck and coot hunting seasons in zones 2 and 3, High Plains Unit

Jan. 13, First day of spring turkey hunting permit sales

Jan. 13, Crow hunting season opens statewide

Jan. 15, Antlerless elk season closes

Jan. 15, Youth, Landowner, Season Choice and River Antlerless, and Gifford WMA deer hunting seasons close

Jan. 15, Prescribed burn training workshop, Red Cloud Community Center, Red Cloud

Jan. 15, Big game informational meeting Wildcat Hills Nature Center, Scottsbluff/Gering

Jan. 16, Prescribed burn training workshop, Lancaster County UNL Extension, Lincoln

Jan. 16, Big game informational meeting, Lake McConaughy Visitors Center, Ogallala; St. Paul Civic Center, St. Paul

Jan. 17, Dark goose hunting season closes in North Central Unit

Jan. 17, Prescribed burn training workshop, Upper Loup Natural Resources District, Thedford

Jan. 18, Nebraska Fish and Game Association Discover Ice-Fishing classroom event, Yanney Heritage Park ERC, Kearney

Jan. 18-Feb. 9, Statewide light goose and white-fronted goose hunting seasons

Jan. 19, Schramm Sunday Speaker Series, Schramm Education Center, Gretna

Jan. 19, Discover Ice-Fishing on-ice event, Fort Kearny Lake No. 6, Kearney

Jan. 21, Prescribed burn training workshop, North Platte NRD, Scottsbluff

Jan. 21, Insect Investigations Educator Workshop, ESU No. 7, Columbus

Jan. 22, Nebraska Game and Parks Commission meeting, Lincoln

Jan. 23, Prescribed burn training workshop, Northeast Community College Lifelong Learning Center, Norfolk

Jan. 28, Growing Up WILD Educator Workshop, North Creek Child Development Center, Lincoln; ESU No. 7, Columbus

Jan. 31, Hunting seasons close for November late doe/fawn antelope, fall turkey, pheasant, quail, partridge, grouse and squirrel

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