Beaver Archives - Eva Varga


January 24, 20171

To finish up his Second Class rank requirements for Boy Scouts recently, I was helping my little man find photographs of wildlife that he has observed. As we dug through our photo archives, I was reminded of a fun little Oregon Nature Quiz: Early Summer Edition that I posted several months ago. I had posted it with the intention of making it a quarterly series but sadly, life distracted me and I let it slip my mind.

Oregon Nature Quiz #2: Wildlife Edition

How Well Do You Know Oregon?

Here are five of the photos my son selected to submit to his Scoutmaster. Can you identify the wildlife represented here? Whose Been Here? Oregon Nature Quiz: Boy Scout Rank Wildlife Edition @EvaVarga.net

Who Am I? Oregon Nature Quiz: Boy Scout Rank Wildlife Edition @EvaVarga.net

What Happened Here? Oregon Nature Quiz: Boy Scout Rank Wildlife Edition @EvaVarga.net

I'm Friendly. Or Am I? Oregon Nature Quiz: Boy Scout Rank Wildlife Edition @EvaVarga.net

My, What Big Teeth You Have. Oregon Nature Quiz: Boy Scout Rank Wildlife Edition @EvaVarga.net

Answers:

1. North American Raccoon tracks along the banks of a river

In the wild, raccoons often dabble for underwater food near the shore-line. They then often pick up the food item with their front paws to examine it and rub the item, sometimes to remove unwanted parts. This gives the appearance of the raccoon “washing” the food.

Originally, raccoon habitats were solely deciduous and mixed forests, but due to their adaptability they have extended their range to mountainous areas, coastal marshes, and even urban areas. Though previously thought to be solitary, there is now evidence that raccoons engage in gender-specific social behavior. Related females often share a common area, while unrelated males live together in groups of up to four animals to maintain their positions against foreign males during the mating season, and other potential invaders.

Intrigued by animal tracks and wildlife signs? Check out these ideas for Exploring Animal Tracks with students.

2. Pacific Tree Frog

Pacific tree frogs are common on the Pacific coast of Oregon and Washington. They occur in shades of greens or browns and can change colors over periods of hours and weeks. They occur in shades of greens or browns and can change colors over periods of hours and weeks. Eggs of the Pacific tree frog may be consumed by the rough-skinned newt and other amphibians.

They are found upland in ponds, streams, lakes and sometimes even further away from water. The Pacific tree frog makes its home in riparian habitat, as well as woodlands, grassland, chaparral, pasture land, and even urban areas including back yard ponds.

3. Black Bear claw marks and Acorn Woodpecker holes on the trunk of an apple tree

In the early fall, when the apples are ripe, it is not uncommon to see claw marks on apple trees, particularly in old pioneer orchards that have been abandoned. Brown and American black bears are generally diurnal, meaning that they are active for the most part during the day, though they may also forage at night.

Most bears have diets of more plant than animal matter and are completely opportunistic omnivores. Knowing when plants are ripe for eating is a learned behavior. Bears may mark territory by rubbing against trees and other objects which may serve to spread their scent. This is usually accompanied by clawing and biting the object.

Interested in learning more about animals and the study of wildlife? Check out these great animal webcams.

4. Golden Mantle Ground Squirrel

Scientists classify the golden-mantled ground squirrel as a true ground squirrel, though it will climb trees to reach seeds. Its genus name Spermophilus is Greek for “seed loving.” Like other ground squirrels, the golden-mantle packs seeds and fruit in its cheek pouches and stores the food in burrows, puts on a thick layer of fat, and hibernates in winter. Golden-mantled ground squirrels eat their stored food in early spring, when seeds and fruit are scarce. In addition to seeds and fruit, the omnivorous ground squirrel eats fungi, insects, bird eggs, small vertebrates, and carrion.

Though the golden-mantled ground squirrel can vocalize, it remains silent most of the time. When alarmed, it chirps and squeals. Though not especially aggressive, it growls when fighting with other ground squirrels. Though tempting, it’s not a good idea to feed these or any other wild animals; it distracts them from searching for natural foods, which they must eat in large quantities to survive. Unlike most other ground squirrels, the golden mantle is a loner. It only spends time with others of its kind as a youngster with its mother and siblings.

5. North American Beaver teeth marks on the trunk of an oak tree

Beaver (Castor Canadensis) are known for building dams, canals, and lodges (homes). Their colonies create one or more dams to provide still, deep water to protect against predators, and to float food and building material. While they don’t generally use trees of the size pictured here in their dams, it is fascinating to watch the process of a beaver dam under construction which play a critical role in the ecology of our streams. Learn more in my post, The Industrious Beaver: Nature’s Engineers.



July 10, 2016

North American Beaver (Castor Canadensis) play a critical role in the ecology of our streams. Their dams create pooling of water upstream, which creates wildlife habitat for many dozens of wetland and slow-moving water species that wouldn’t otherwise be in such riparian habitats.

These industrious mammals provide a fascinating topic for middle school science investigations. Here you will find a variety of resources and materials to engage middle schoolers in real science related to nature’s engineers, Castor canadensis.

A Look at the Industrious Beaver: Nature's Engineers (A Middle School Unit Study) @EvaVarga.net

Beaver Anatomy & Physiology

Beavers are the largest rodents in North America, and they spend most of their time in the water. To protect themselves from the cold and wetness they have waterproof reddish brown or blackish brown hair. They have small, round, brown ears, and powerful back legs for swimming. A beaver’s front legs are not as large or as strong as its back legs.

Beaver skulls and teeth are very big. The two front teeth are orange colored, and they can be up to 5 mm wide and between 20 and 25 mm long. These teeth grow throughout the animal’s life, and they are used for cutting wood. Without these teeth beavers could not cut down or eat trees and wood. Beavers also have see-through eye lids, and closable nostrils and ears for swimming underwater.

Beavers also have anal and castor glands, which they use to mark their territory. These glands are located beneath the tail. The beaver utilizes the oily secretion (castoreum) from these scent glands to also waterproof its thick fur.

The beaver has a thick layer of fat under its skin that helps keep it warm underwater. Beavers have long sharp upper and lower incisor teeth that they use to cut into trees and woody vegetation. These teeth grow throughout the beaver’s life. A beaver’s tail is broad, flat, and covered with large black scales.

A Look at the Industrious Beaver: Nature's Engineers (A Middle School Unit Study) @EvaVarga.net

Beaver Ecology & Natural History

Important natural processes, such as energy flows and chemical cycles, result from the interaction of species within a community. Food webs of trophic (trophic – pertaining to nutrition) interactions among species are one example of how multiple soil-plant, plant-plant, plant-animal, and animal-plant relationships link together within a functioning community. Some species can be highly influential in their communities, even if they occur at relatively low population densities. When the presence and actions of this species tend to form the foundation of how other species relate to each other in the community, we often call the influential plant or animal a keystone species.

“Keystone” is a metaphor equated to the stone in the middle of an arch in a building. Removal of the keystone leads to destabilization if not outright collapse of the other elements that “lean on” or depend upon that keystone.

A Look at the Industrious Beaver: Nature's Engineers (A Middle School Unit Study) @EvaVarga.netThe beaver is often cited as an example of a keystone species because through its dam-building behaviors it has major influences on both the vegetation of an area and the water table. In turn, these factors have strong influences on the abundance and quality of habitat for many other plant and animal species within the community. They engineer, or create, habitat that supports greater biodiversity that would otherwise not exist.

No other animal with the exception of man can significantly alter its habitat to suit its own needs and desires. Native Americans revered the beaver and referred to them as “Little People” for this reason.

In one of the first images of its kind, night-vision cameras recently captured photos of native beavers and invasive nutria working together to build a dam across a channel at Smith and Bybee Wetlands Natural Area in Portland, Oregon.

Beaver Unit Study Resources

Act out a short skit to teach others about the natural history of the beaver – its adaptations for its environment as well as the impact humans have had on it throughout history.

Dress up a volunteer as you learn about the structural and behavioral adaptations of beavers.

Explore the website Beavers: Wetlands & Wildlife to learn more about beavers and their impact on the ecology.

Learn about the history of the Fur Trade and Beaver Ecology including numerous Historical Source Documents.

Learn about Beavers and Climate Change Adaptation Strategies – A Report from Wild Earth Guardians.

Download the Beaver Monitoring App and help scientists study how beavers could be used as a tool for stream restoration and mitigating impacts of climate change.

Reach out to your local watershed associations to learn about watershed monitoring and restoration projects that impact beavers. How can you get involved?

Visit and observe an ecosystem created by beavers in your local area (contact Fish & Wildlife for assistance in locating a dam if you are unfamiliar). Keep a journal of your observations.

zoology

You might also be interested in my 10-week inquiry based science unit introducing middle level students to the study of animals: Zoology: Amazing Animals. Lessons include scientific classification, identifying animal tracks, ecology, and animal behavior.