Lesson A12: How Humans Harm Other Species

Key Ideas   Unit Checklist

  Video Lesson

Humans have enormous influence over most other species -- and many of our influences are harmful. Can we change our activities to ensure survival of other species? Should we make such changes? How would such changes affect humans? … and the questions continue!

  Lesson A12: How Humans Harm Other Species

Alberta’s Disappearing Grizzly Bear

You don’t want to face a grizzly bear. They may not be cuddly animals, but they are very important to Alberta’s ecosystem. If a grizzly bear sees you, it will almost always run away. Bears attack people when they are frightened by the human’s sudden presence or when they are protecting cubs. Dogs, noises, and unpredictable movements can irritate a bear and drive it to attack as well.
Reading and Materials for This Lesson

Science in Action 7
Reading: Pages 66–69

Materials:
No other materials are needed for this lesson.

Figure A.4.12.1 – A mother grizzly bear walks with her cubs.
Figure A.4.12.2 – An adult grizzly bear enjoys a good view from a rocky ledge.
Humans and Bears do not Mix

Bears are part of Alberta’s famous wildlife. People often are excited to spot one on the side of the road. Sometimes, they want photographs, and they lure the bear closer with food offerings. The bears learn very quickly to associate food with humans.

Bears have a keen sense of smell. When a bear smells food in a garbage bin, it will risk entering a human development. Bear-proof garbage bins are available, but they are not always used. If a bear finds food, it will return again. This behaviour is a nuisance to humans. People who leave food for their dogs on their deck might wake one morning to find a grizzly bear gobbling it up.

Grizzly Bears Need Lots of Space

Each grizzly bear needs a large uninterrupted range to find and hunt sufficient food. As grizzly habitats continue to shrink and fragment due to human development, hungry bears have no choice but to seek food where they can. They often are forced to go near humans to get their food. Because of this, people see them more often, and they assume that grizzly bear numbers are increasing. These encounters are misleading. Instead, they indicate increasing desperation among the grizzlies.
Figure A.4.12.3 – When grizzly bears and humans mix, the bears usually lose.

The grizzly bear population in Alberta is in trouble. Grizzly bears were listed as a threatened species under Alberta’s Wildlife Act in 2008. Although grizzlies are no longer hunted, 19 human-caused bear deaths were recorded in 2014. This might not seem l a large number of deaths, but this is a big part of the total population of grizzlies in Alberta. Fewer than 700 grizzly bears  are estimated currently to live in Alberta.

Scientists estimate that in the 1800s more than 6000 grizzlies in Alberta. The bears prefered to roam the open prairie. Most of this area is now developed into agriculture, industry, and housing. The grizzly has little natural ecosystem left to call home. Grizzly habitat that remains is of poor quality.

When Do We Protect a Species?

To determine a species’ protection status is complicated. Is it of special concern, threatened, endangered, extirpated, or extinct?
Figure A.4.12.4 – An adult grizzly bear enjoys a good view from a rocky ledge.

Several factors are used to calculate whether a species is at risk or not. If nothing is done to protect the grizzly bear, its numbers will continue to decline. If the grizzly population becomes too small, restoring the species will be very difficult in Alberta. When populations decrease in size, their diversity also decreases. As in ecosystems, diversity is key to a healthy population of individuals.

Some Species are Extremely Important

Ecologists call the grizzly bear an umbrella species. The health of an umbrella species is the first indicator of trouble ahead for the ecosystem. Because grizzly bears cover large ranges and consume a wide variety of organisms, a healthy bear population indicates an abundant diversity of organisms present. A healthy bear population indicates a well-branched food web. Ultimately, it indicates a healthy ecosystem. The opposite is also true. Grizzlies are suffering because the ecosystem is unhealthy, out of balance, and fragmented.
Figure A.4.12.5 – Grizzlies can be particularly dangerous when defending cubs.


Figure A.4.12.6 – Grizzlies like eating berries very much! Photo by NPS Photo/Jacob W. Frank.

Figure A.4.12.7 – Grizzlies have excellent salmon-catching skills.

 Watch More

Wolves vs Grizzly Bears

The majestic grizzly bear once reigned over most of North America. This species is now reduced to isolated populations. In one place, however, grizzly life is still relatively easy. In Yellowstone National Park in the United States, grizzlies have a large protected range in which to live, hunt prey, and raise cubs. Still, change seems ever-present. Grizzly life became more complex when wolves were introduced to the park recently. American wolves needed protection, too. Before human development, bears and wolves existed together. Now, these two top predators must battle again for prey. Watch this video to see how the battle progresses.

Figure A.4.12.8 – The boreal chorus frog is common throughout central North America.
Figure A.4.12.9 – The wood frog is another frog common to many parts of North America.


Frogs and Wetlands

Frogs are important species in Alberta wetland ecosystems. Most of Alberta’s frog species are not currently at risk. However, wetlands are drained, paved over, and farmed. As Alberta continues to lose wetland ecosystems to industrial development and human settlement, frogs may be in trouble in the future.

Wetlands are an essential part of the larger Alberta ecosystem. Humans depend on them for several reasons. They supply food and fresh water for people. They filter and clean contaminated water and they help control flooding.

Frog populations and wetland ecosystems are closely linked – if one is suffering, the other probably is suffering, too. Keeping watch on Alberta frog populations is important.
Figure A.4.12.10 – Chorus frogs have a loud mating call.

  Lesson Activity


FrogWatch: You Can’t Fix it if You Don’t Know What’s Broken

Alberta’s wetlands are disappearing. These are important frog habitats. Some Alberta frog populations are in sharp decline. In this activity, you will learn more about Alberta frogs and how to monitor them.

Instructions

This activity uses a website that collects data from people such as you. The data goes to scientists and leaders who develop guidelines, recovery programs, and legislation to protect frog species at risk in Alberta
The website will ask you to join the program, but that is your choice. It is a government program that is safe to join, but joining is not necessary to complete this activity.
ALWAYS ask your parents or guardians before entering personal information online at any website.
Instructions:

    1. Go to Frogwatch.ca. Read the Welcome story on the front page.

    2. Click on the how-to guide. Read “About Frogs” carefully. Here, you will learn about Alberta’s key frog and toad species. You will learn how a frog population in an area is estimated. Frogs are difficult to see. They are even more difficult to lure and catch. A catch and release method would not work here. However, male frog behaviour offers a convenient and accurate way to estimate their numbers. After sunset in the spring, romance is on the minds of male frogs. Each frog species calls to attract mates and to establish its territory. Although most birds and other vocal species are inactive at night, frogs are at their vocal best.

    3. Frog calls can be used to make population estimates. But you need to learn which frog is which! Click the “Identifying Frogs” link under the mouse-over “how-to guide” at the top of the page. Read about indicator species.

    4. After you have finished reading, choose “Alberta” under “Choose province or territory.” You will see profiles for eight Alberta toads and frogs. Read each introduction.

    5. Then, click “Learn more” for each frog. Here, you will learn a lot about each frog. Each frog page has a sound file. Listen to the frog’s call – play these several times. Try to remember them! For fun, you might close your eyes and have someone else play the calls; then, see if you can identify the frog. If you were actually to count frogs for the FrogWatch program, identify frogs properly would be very important because bad data can mean bad decisions by scientists and leaders.

    6. Now, you are ready for field training. Click “Field Training” under the how-to guide. Here, you will find a link to “What are Amphibians?” Read this page carefully.

    7. It is not necessary to go out and actually count frogs. But if you do decide to count frogs in your area, go back to the how-to guide and read “Monitoring Tips” and “Record Observations”. If you can, choose a pond area that is nearby. Frogs tend to be most numerous around and in wetland ecosystems. You must also read the “Safety First” section on the page before going outdoors to do any frog counting.
ALWAYS ask your parents or guardians for permission before you go to any nature area.

Questions:

Now that you are a frog monitoring expert, think about the following questions very carefully. Then, type or write your answers. If you have to review the information at the FrogWatch website to answer the questions, please do so. Review is a good thing! After you have your answers, click the questions for feedback.

Frogs are amphibians. Although amphibians have lungs, they also breathe through their moist skin and the lining of their mouths. Instead of drinking water, they absorb water through their skin. This means that frogs absorb pollution through their skins as well. Frogs live on land and in water, so they are vulnerable to changes in both ecosystems. This sensitivity to changes in air, water, and land make the frog a great indicator species. By keeping track of changes in frog populations, ecologists obtain a picture of how the ecosystem is changing. Lots of frogs means a healthy wetland ecosystem. Frog calls on the decline may be the first sign of an ecosystem in trouble.
Frog calls are distinct, so they are easy to distinguish from other sounds in an ecosystem. Frog calling is also predictable. If males are present, they will call, especially under moist conditions after dark in the spring. By counting the number of calls you hear in a specific area over a specific period of time, you can have a population estimate. Your data will be compared to data from years past. Ecologists will use the data to calculate changes in the frog population from one year to the next. They will not know how many frogs are present.  However, they can determine if the population is stable, increasing, or decreasing, and at what rate.
To record only frog calls and all frog calls is important. You must be able to identify each call to do this. If calls from birds and other animals are included accidentally, the frog estimate will be inaccurate. It will indicate either more frogs than there really is, or that there are frogs where none exist.
Knowing where frogs are and where they aren’t is important, too. If frogs were recorded in your area in the past but not now, something may have disturbed their habitat. Ecologists will want to study the habitat to see how it changed.
Frogs are the “conveyer belts” of the ecosystem. They move nutrients from ponds and lakes onto land. Frogs are small organisms, but each frog lays thousands of eggs. These eggs are an important food source for many other species. Adult frogs are also predators of many species, including insects that we consider as pests. They are a highly interconnected central part of the wetland food web.
Ecologists will use the FrogWatch data to make recommendations to the government. If frogs are disappearing from an area, they can recommend that it be monitored more closely. If the ecosystem is suffering, the government can act to protect the area from further damage.
By monitoring the populations closely, ecologists can detect changes sooner, so they can alert the government and take action sooner. It is much easier to deal with an ecosystem problem while it is still small. It is much easier to protect a species when its population is still fairly healthy and it still has some habitat.  By monitoring, we can also make better connections between frog population health and wetland ecosystem health.



  Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to guide your learning.

Unit A Lesson 12 Self-Check

Instructions


Complete the following 6 steps. Don't skip steps – if you do them in order, you will confirm your understanding of this lesson and create a study bank for the future.

  1. DOWNLOAD the self-check quiz by clicking here.

  2. ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.

  3. COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.

  4. REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.

  5. SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.

  6. CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher. To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!


Self-Check Time!
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Self-Check Quiz Answers

Click each of the suggested answers below, and carefully compare your answers to the suggested answers.

If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.

An endangered species is likely to become extinct. Scientists can recommend that a species be listed as endangered. When a species is listed as endangered, the federal government must develop a recovery strategy for the species. It must identify habitat that is crucial for its survival and then act to maintain, protect, and restore that habitat.
Extinctions are natural and they have occurred throughout Earth’s history. In fact, Earth has experienced five major mass extinction events. In each case, a rapid, widespread, and significant loss of species occurred naturally. Many experts believe we are now in a sixth major extinction event. This one is caused by human activity. Since 1900, the rate of extinctions has increased approximately 100 times. Global climate change and loss of habitat are the two main reasons for current extinctions. Why should we care? We are part of our ecosystems. We need diverse healthy ecosystems filled with complex food webs to meet our needs for survival. Every species works to make our ecosystems healthy. Rapid widespread species loss puts the survival of the human species at risk as well. Humans cannot live without our ecosystems.
That organisms must continuously adapt to natural changes in their ecosystems is correct. Ecosystems change seasonally, and they change over time as the climate and other abiotic changes occur. In fact, ecosystems go through periodic destruction. Those ecosystems not only recover but natural cycles of destruction rejuvenate them. The critical difference between natural and man-made change is that organisms cannot adapt quickly to man-made changes. Man-made changes often are so abrupt that species cannot respond fast enough to survive. Often, a species faces multiple man-made threats at the same time. The species that cannot adapt to all these man-made changes faces extinction.
Scientists can recommend that the Alberta government secure protected status for the grebe’s habitat. This ensures the ponds and lakes it nests in remain as they are. The government can ensure that the land around those ponds and lakes is protected from chemicals and fertilizers that might enter the water. Housing could be restricted around the pond or lake. The grebe’s prey species must be protected, too. Fishing and motorized boating on the water can be restricted so the birds and their nesting sites are not disturbed.
A species of special concern, such as the western grebe, may become threatened or endangered in the future. The requirement of a very specific habitat and the loss of much of that habitat place the western grebe in this category. The “at risk” category under which a species is listed is very important. It determines what level of protection the species receives under Alberta’s Species at Risk Act. For a species of special concern, a conservation plan is developed. This plan guides the management of its habitat. For example, these guidelines recommend that no boating and no fishing signs are placed where grebes nest.