Last updated: December 31, 2020
Lesson Plan
It's Not Easy Being Grizz
- Grade Level:
- Middle School: Sixth Grade through Eighth Grade
- Subject:
- Science
- Lesson Duration:
- 90 Minutes
- Additional Standards:
- NGSS MS-LS2-1. Analyze & interpret data to provide evidence for the effects of resource availability on organisms & populations of organisms in an ecosystem. MS-LS2-3 Develop a model to describe the cycling of matter and flow of energy among an ecosystem
Essential Question
Why are key stone species important in food webs? What roles do grizzly bears, whitepark pines, and squirrels play in the Crown of the Continent food web?
Objective
Students will understand the complexities of a segment of the food web that involves grizzly bears, whitebark pines, and squirrels.
Background
This is a game illustrating opportunistic grizzly bear feeding. Bears follow a seasonal cycle of food-gathering, changing foods as different plants become ripe or as other foods become available in other ways. This game takes a fair amount of preparation, but it is worth it! Your students will play the game in a marked playing field, shown below. For more links to information about bears and identifying bears, visit Unit Four of the K-3 Guide.
Grizzly bears are 300 to 600 pound animals with 4-inch claws and powerful jaws. Contrary to some opinions, they are also shy – most of the time… Only about 5% of their food is larger animals, on the average, and they are masters at finding the plants that are ripe at different times of the year. Some of the bears’ “seasons” for different foods are only a few days long – then they move to the next “berry du jour”. In the game you will play, you will move through the seasonal cycle of the grizzly bear, foraging for different foods in different months of the year. The object for bears, and for you, is to gather enough calories to put on enough fat to last through the November-to-April hibernation.
The foods you will eat, in order from spring to late fall, are (1) carrion from winter-kill, (2) grasses, sedges, new leaves and newborn fawns or calves, (3) glacier lilies, ground squirrels and marmots, (4) cutworm moths under rocks in the high alpine zone, (5) ladybugs, (6) huckleberries, and (7) whitebark pine nuts.
Grizzlies use their long claws for a number of things including: to dig up roots and burrowing animals, and to remove pine nuts from cones. Grizzlies also have sensitive and flexible lips and tongues for eating bugs, and the “hump” on their backs is a huge shoulder muscle for digging and turning over rocks.
Whitebark pine is especially important to them for three reasons. The season when pine nuts are ripe is long (August to October), the nuts inside whitebark cones are high in calories, and pine nuts are the last natural food of the season – ready just before bears hibernate. Whitebark pines are also located high in the subalpine zone, just below treeline, near where the grizzlies dig their dens. Red squirrels are an important player in the grizzly’s whitebark pine diet. Squirrels bury the cones close together in “middens” of one to thirty square yards (meters). Sometimes a single squirrel will bury 800,000 cones in a single year! Obviously, this concentrated source of food is a “gold mine” for a bear.
When grizzlies aren’t around, black bears climb whitebark pine trees for cones, and eat the seeds in the tree. Black bears sometimes lose all the hair from their chests and inside front legs because the pitch on the tree trunk pulls it out.
Cutworm moths spend much of the year out on the great plains, but they migrate by the millions to alpine areas to escape the heat of the summer. They hide under rocks in talus slopes. Bears turn over hundreds of rocks to find them, because the moths are high in fat and protein. Ladybugs come to the alpine in September to hibernate, also by the millions. Grizzlies find them by the bucket–load on the north and east slopes above treeline. The ladybugs hibernate on those slopes because insulating snow is deepest there.
Preparation
- 10 tag-board signs (8 1/2 X 11 or larger) with months in large letters, “April” through “November”, plus “hibernate”
- 10 colors of tag-board paper, cut with paper cutter into 2-inch squares (need 12 of each color per student, 2 of them marked with a dot on the back side) Note: regular thin colored paper blows away in the wind – use heavier
- At least 10 orange playground cones (more is better) or plastic flagging to mark two concentric rings of 50 and 100 feet diameter
- Stick-on name tags, one for each student and markers
- Clock with timer setting or stopwatch
Procedure
1. Begin by reviewing what students already know about bears. Read together the narrative above and discuss how, in this activity, students will mimic how bears change their feeding behavior to suit the seasonal availability of different foods.
2. Each color of the paper squares represents a different seasonal food source for bears. There should be 12 squares of each color for each student “bear”. Here is an example of how the paper squares would be divided and marked, keeping in mind that you can change the colors to suit your preferences:
- White – carrion – April – 10 per student plain, 2 per student marked with 2 dots
- Blue – grass/leaves/fawns – May – 10 per student plain, 1 per student marked with a dot, 1 per student with 2 dots (fawns)
- Red – glacier lilies/marmots – June – 10 / student plain, 1 per student with one dot, 1 per student with 2 dots (marmots)
- Green – cutworm moths – July – 10 / student plain, 2 per student with a dot
- Orange – huckleberries – August – 10 / student plain, 2 per student with a dot Purple – ladybugs – September – 10 / student plain, 2 per student with a dot
- Yellow – whitebark pine – Sept. / Oct. – 10 per student plain, 2 per student with 2 dots (you may wish to throw in 2 or 3 extra squares with 4 dots on the back, to represent some giant squirrel middens)
- Pink – apples/garbage/dog food – outer edge of inner circle - !0 per student plain, 2 per student with a dot
- Chartreuse – sheep/cattle – middle of inner circle – 10 per student plain, 2 per student with 2 dots
Game 1:
Set up the playing field with cones according to the dimensions in the drawing (approximately). There should be a 50-foot circle and a 100-foot circle outside of it. The inner circle is where humans live (in the valleys). The bears will forage mostly outside the outer circle (high in the mountains). The paper squares should be spread evenly through each month according to the drawing. Be sure to place the squares with dots so the dots are down and not visible.
Have 3 or 4 students be “humans”, who stay in the center 50-foot circle. Their job is to protect the apples, garbage, dog food, cattle and sheep from being “stolen” by the bears.
The rest of the class will be grizzlies. Have them begin in “hibernation”. Tell them they will be given 30 seconds for each month. Their job is to forage through the squares and collect the squares with dots. They may go anywhere inside the inner circle, but outside they must stay in the proper month for the 30 seconds. If they are tagged by a human in the inner circle, they must give up one of their “dot” cards (the effects of capture and relocation). If they are tagged a second time, they are a “repeat offender” and will be considered dead.
Time them, 30 seconds per month, through the year into hibernation. There they will count their dots. If they have 15 dots or more, they made it into hibernation in fine shape. If they have 12 to 14, they made it, barely. Less than 12, they will never wake up…
Your objective is to set up the game so a few bears do not survive. This is the way it happens every year. In the unlikely event that all of your “bears” survived, simply say it was a great year for bears.
Do some grizzly bears die every year? How would you define a stable population? Can poor nutrition affect reproduction as well as mortality?
Game 2:
Explain to the students that the first game was played under ideal conditions for bears (even then, some probably died). It was in the 1800’s. In the early part of the 1900’s, a shipment of white pines from overseas brought pine blister rust to North America. It killed 80% of the whitebark pines, and few have come back because we humans also suppressed fires which make suitable openings for re-planting the whitebarks. Ask them to give you all but 4 of the whitebark pine squares with dots. Then have them replace the squares, dots-down, in the proper months, and gather in the hibernation area.
Will the whitebark pine demise change your survival strategy? How? Will knowing how many dots you need affect your risk-taking in the human-populated area?
Choose new “humans” to occupy the center circle. Play the game again. Compare results with game one.
What was the critical time of the year for most of you? Why were the cattle and sheep in the most difficult area to raid?
Game 3:
Have the students replace the squares again and announce that now we are moving into modern times. Humans are now building homes in the woods and foothills, and the humans can now move freely in the 100-foot circle. And, there are more humans. Choose 5 or 6 (assuming an average-sized class) replacement “humans” and send them to occupy and protect the larger circle. Play the game again and compare results.
Are people now living in huckleberry areas? With the absence of whitebark pines, is the huckleberry area especially critical now? How important is it to have a large bear sanctuary area like the Waterton-Glacier International Peace Park?
Game 4 and 5:
Remove most of the huckleberries (bad seasons are fairly common) and play Game 4. Compare results. For Game 5, you will need the stick-on nametags. Have about one-half of the girls put on a nametag. They are the females with cubs. They need at least 15 dots to keep their cubs alive. Play the game again and compare results. You may also wish to make some of the females “pregnant” with the nametags.
Variations and Extensions:
This game has a number of variations, mixing and matching the adjustments of food supply. You may also wish to invent a “peck-order” of dominant and submissive animals. Use the nametags and have some bears be dominant, some be cubs and yearlings, and give the dominant bears a 5 – 10 second head start into the next month (simulating getting the choice feeding areas).
Assessment Materials
Many options… Have students write a short story about the year of a bear. Have them represent the same thing without words, in artwork. Have them compare the seasonal changes in their own diets to grizzly diets.