Grade by Grade
D. Structures and Mechanisms · Strong and Stable Structures

Animal Builders and Human Builders: Effects on the Environment

D1.2 D2.1 A1.1 A3.1About 40 minutes
Learning goals
  • I can describe structures built by animals, like dams, lodges, nests, webs and honeycombs.
  • I can compare structures built by animals with structures built by humans.
  • I can describe good and harmful effects that animal and human structures have on the environment.
  • I can suggest ways people can build that are kinder to the environment.

Words to know

environment
Everything around a living thing: land, water, air, plants and animals.
habitat
The place where a plant or animal lives and finds food, water and shelter.
impact
An effect. An impact can be helpful or harmful.
wetland
Land that is soaked with water most of the time, like a marsh, a swamp or a beaver pond.
dam
A structure that holds back water. Beavers build dams, and so do people.

Nature's engineers

Long before people built bridges and houses, animals were building amazing structures. A beaver cuts down trees with its teeth and builds a dam across a stream. A bird weaves a nest. A spider spins a web. Bees build a honeycomb.

Every structure, whether an animal or a person builds it, changes the environment around it. Today you will assess (judge) those changes: which are helpful and which are harmful?

Some animal builders in Canada

  • Beavers build dams of sticks, mud and stones across streams. The dam holds back water and makes a pond. In the pond, they build a lodge, a dome-shaped home with underwater entrances that keep predators out.
  • Birds build nests from twigs, grass, mud, feathers and moss. Robins use mud to hold their nests together.
  • Spiders spin webs from silk made in their own bodies. A web is a frame structure that catches insects.
  • Honeybees build honeycomb from wax made in their own bodies. Each cell has six sides, and the cells fit together with no gaps.
  • Wasps chew wood into a kind of paper to build their nests.
  • Muskrats build lodges in marshes from cattails and other water plants.
A beaver lodge made of sticks and mud sits in a pond, with a long beaver dam behind it and autumn forest around.
The beaver's dam holds back the stream to make a pond, and the dome-shaped lodge is its home. Both change the environment around them. AI-generated image
pondlodgedamstream
A beaver dam holds back a stream and makes a pond. The beaver's lodge sits in the pond.

Effects of a beaver dam

A beaver dam has big effects on the environment, some helpful and some harmful.

Helpful effects:

  • The pond and the wetland around it become a habitat for fish, frogs, ducks, turtles, insects and moose.
  • The wetland stores water, which helps during dry summers.
  • Water slows down in the pond, and mud settles to the bottom, which helps clean the water downstream.

Harmful effects (for some living things and for people):

  • The rising water can flood trees, which then die.
  • Beavers cut down many trees near the water.
  • Ponds can flood roads, trails and farm fields.
Structures built by animalsStructures built by humans
Materialsnatural and found nearby: sticks, mud, grass, wax, silkmany kinds, often brought from far away: steel, concrete, glass, plastic, wood
Sizeusually small (a beaver dam can be large)can be huge: towers, highways, dams, cities
After they are not usedbreak down and return to naturesome materials last a very long time and can become waste
Helpful impactsmake habitats for other living thingsshelter, travel, clean water, electricity, safety
Harmful impactsflooding, cutting trees (beavers)take away habitats, pollution, waste, cutting forests, blocking animal paths
Comparing animal and human structures
Worked example

Let's compare two dams

Compare a beaver dam with a big concrete dam built by people to make electricity.

  1. Same function: both hold back water and make a pond or lake behind them.
  2. Materials: the beaver uses sticks, mud and stones from nearby. People use concrete and steel.
  3. Size: the human dam is usually much, much bigger, so it floods a much bigger area.
  4. Helpful: the beaver pond makes wetland habitat. The human dam makes electricity for homes and can control floods.
  5. Harmful: both flood land. A big dam can block fish from swimming upstream. Some dams have fish ladders, a set of small steps of water that help fish get past.

Both dams hold back water. The human dam is bigger, uses different materials, and has bigger effects, both helpful (electricity) and harmful (flooding large areas, blocking fish).

Building kinder to the environment

People are learning ways to build with fewer harmful effects:

  • Wildlife crossings: bridges or tunnels that let animals cross highways safely. Banff National Park has wildlife bridges, and Ontario has small tunnels under roads for turtles.
  • Fish ladders at dams.
  • Green roofs: roofs covered with plants, which give homes to insects and birds and soak up rain.
  • Bird-friendly windows: glass with patterns, so birds see it and do not fly into it.
  • Reusing and recycling building materials, and using materials from nearby.
WILDLIFE CROSSINGanimals cross abovethe highway safelyhighway
A wildlife crossing is a bridge covered with plants, so animals can cross over a busy highway safely.
Worked example

Let's assess an impact

A town wants to build a new parking lot on a field next to a creek. Assess the impact on the environment.

  1. Who lives there now? Grasses, wildflowers, insects, birds, maybe rabbits and frogs near the creek.
  2. Harmful: the field's habitat is lost. Pavement stops rain from soaking into the ground, so rainwater runs quickly into the creek, carrying dirt and oil.
  3. Helpful (for people): people have a place to park near the store or arena.
  4. Ideas to reduce harm: keep a strip of plants along the creek, use paving that lets water through, plant trees, or make the lot smaller.

The parking lot helps people but harms habitats and the creek. Planning can reduce the harm.

Just for fun

A beaver's front teeth never stop growing. All that chewing on trees keeps them from getting too long. Building a dam is also a tooth-care plan!

Hands-on activity

Animal architect research

You need: books from the library or a website a grown-up helps you choose, paper and pencils.

  1. Choose one animal builder from Canada: beaver, robin, barn swallow, paper wasp, honeybee, spider, muskrat, or another.
  2. Research: What does it build? What materials does it use? What is the structure's function?
  3. Draw the structure and label its parts.
  4. Write one helpful and one harmful (or no-harm) effect it has on the environment.
  5. Then choose a human structure with a similar job (a house, a dam, a net, a shelf). Write one way they are alike and one way they are different.
  6. Present your poster to your family.

What to look for: correct facts from a trusted source, a labelled drawing, at least one effect, and a clear comparison. Safety: look at nests, webs and wasp nests only from a distance; never touch or disturb them.

Your turn

1

Name three animals that build structures and what they build.

2

What does a beaver dam make behind it?

3

Name one helpful effect of a beaver pond.

4

Name one harmful effect of a beaver dam.

5

What is a wildlife crossing?

6

What materials do most animal builders use?

7

Name one way human structures can harm the environment.

More practice: warm-up

1

What do spiders use to build webs?

2

What do honeybees build their honeycomb from?

3

Is a beaver lodge a home or a bridge?

4

What is a habitat?

5

What do fish ladders help fish do?

More practice: on your own

1

Why do animal structures usually have smaller effects on the environment than human structures?

2

How can a green roof help the environment?

3

Why do some buildings put patterns on their windows?

4

A beaver pond floods a hiking trail. Is that helpful or harmful? To whom?

5

Name one thing a beaver dam and a human dam have in common, and one difference.

Challenge

1

Some people say beavers are "nature's engineers". Do you agree? Give two reasons.

2

A new highway will cut through a forest where deer and turtles live. Suggest two ways to build it with less harm.

3

Is every effect of a structure either good or bad for everyone? Explain with an example.

Check your understanding

Quiz

1.

Which animal builds a dam and a lodge?

2.

A spider's web is made of...

3.

Which is a helpful effect of a beaver pond?

4.

Most animal builders use materials that are...

5.

A bridge or tunnel that helps animals cross a highway is a...

6.

Which is a harmful effect of many human structures?

For parents and teachers

Big idea: Students assess the environmental impact of structures built by animals and by humans (D1.2). Animal structures (dams, lodges, nests, webs, honeycombs) use natural, nearby materials and are usually small, but a beaver dam can change a whole area, creating wetland habitat while flooding trees and roads. Human structures are often much larger and longer-lasting, with bigger effects, and people are finding ways to reduce harm (wildlife crossings, fish ladders, green roofs, bird-friendly glass) (A3.1). The animal architect poster is a small research project (A1.1).

How to help: Help your child pick trustworthy sources (library books, Canadian Wildlife Federation, Hinterland Who's Who, provincial park websites). On walks, look for nests, webs and, if you live near water, beaver signs such as chewed stumps.

Common difficulties:

  • Seeing effects as all good or all bad. Encourage "good for ___, bad for ___" thinking.
  • Thinking animals never change the environment. Beavers change it a lot!

Safety: observe nests, webs and especially wasp nests from a distance; never disturb wildlife.