Brooks River Brown Bears: Inheritance and Variation of Traits

Observing the Brown Bears

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Students begin by reviewing and discussing their categorizations of brown bears’ specific traits as being either inherited or acquired. After observing a photograph and video clip, students find out that bears learn (acquire) their fishing techniques. Students observe individual bears on the live bear cam and record their observations on a data sheet. When they are done, the class watches a video clip of bears using different fishing techniques. The lesson concludes with students using what they have learned about bears’ fishing techniques in order to come up with a question they might answer while watching a live cam.


Why are there differences between the ways individual brown bears look and act?


Teacher Materials

Student Materials

Lesson Preparation


Review Inherited and Acquired Traits

  1. Review the Katmai Brown Bear Identification handouts students completed in Lesson 1. For each trait, have students raise their hand to vote whether they marked it as “Inherited” or “Acquired.” Use the Key to Brown Bear Identification handout to check their answers.
    • Help students deepen their reasoning and explanations by asking how they reached their conclusions.
    • Remind students that acquired traits are those that a bear learned (like fishing techniques) or that happened after it was born (like getting scars or a torn ear).
  2. Display and discuss the Brown Bears Fishing at Brooks Falls photograph.
    • Zoom in on the two bears standing at the top of the falls. (NOTE: place the mouse over the picture to zoom in. Move the mouse out of the picture to zoom back out.) Ask students to identify physical differences between them and decide whether the traits are inherited or acquired. Students may notice:
      • One bear is lighter in color than the other—inherited.
      • One bear has a steeper brow ridge above its muzzle (nose)—inherited.
      • The bears have scars in different places—acquired.
    • Broaden the focus to the two bears sitting in white water below the falls. Ask students to identify acquired behavioral differences between the four bears. Students may observe and infer:
      • They fish in different places and by standing or sitting, so they might have learned different fishing techniques.
      • Some fishing spots might be better, so the bears there might be bigger and stronger than others (dominant).
  3. Show the Brooks Falls Highlight 2 video clip, which shows two bears standing and “wrestling” in the river.
  4. When the video is done, ask students to describe what they saw. Confirm that it is difficult to know whether the bears were playing or fighting, but that they were definitely testing each other’s strength. In general, the strongest, largest bears are the most dominant, “top” bears. That means they get the first choice of fishing spots or anything else that other bears might want.

Introduce the Activity

  1. Let the class know that today they will observe and collect data about the brown bears from live-streaming video at Brooks River. Explain:
    • Multiple cameras are installed along the river every summer and early fall. Two are mounted near the falls.
    • The cameras are being operated remotely. The operator will pan or zoom in when it looks like something interesting is happening.
    • The bears are wild animals, so people do not approach them.
  2. Give each student a Brooks River Brown Bear Data Sheet handout, and point out that there are spaces for them to collect data about the traits of three individual bears. They can write or draw their observations. These include:
    • Age (cub, subadult, or adult)
    • Body shape and size
    • Face shape and size
    • Ear shape and size
    • Fur color
    • Scars and wounds
    • Claw color
    • Fishing techniques
    • Other observations

Remind the class that they can refer to their Katmai Brown Bear Identification handout for more information about what to look for in each set of traits.


Watch Brown Bears

  1. Show the live streaming video you selected (the Falls, the Riffles, or the Lower River). Gauge how long to have students watch by the number of bears on camera and the students’ attention spans. (If no live cams are streaming, show the Brooks Falls Highlight 3 video, which shows a mother moving her cubs away from a male.)
  2. Call on student volunteers to describe different bears’ physical and behavioral traits that they observed and documented from the video. In particular, ask students to describe any fishing behavior they might have seen. Write their observations about fishing techniques on the board.

Observe Bears’ Fishing Techniques

  1. Show the Brooks Falls Highlight 4 video, which illustrates bears using different fishing techniques. Remind the class that fishing techniques are learned, acquired behaviors. A mother bear needs to teach her cubs how to fish, and so the cubs usually fish the way their mother does.
  2. As students watch, point out some of the bears' techniques:
    • Stand and wait (Standing on top of Brooks Falls, a bear waits for fish to jump close enough to catch in its mouth.)
    • Sit and wait (Sitting in the white water below Brooks Falls, a bear simply waits to feel a fish.)
    • Dash and grab (A bear runs into the shallows at the far side of river, chases fish, and attempts to pin them to the river bottom with its claws.)
    • Snorkeling (A bear puts its head underwater to look for fish.)
    • Diving (A bear goes completely underwater to look for fish.)
    • Stealing (A bear takes a fish from another bear.)
    • Scavenging (A bear eats fish left behind by another bear.)
  3. Explain that one way to tell apart individual bears is by watching where and how they fish.

Turn and Talk

  1. Tell students to turn and talk with a partner. They should:
    • Refer to the board and identify any fishing techniques they saw in the live-streaming video (if seen)
    • Explain to each other why bears’ fishing techniques are learned and not inherited traits
    • Use what they have learned about bears’ fishing techniques in order to come up with a question they might answer while watching a live cam, and write the question down.
  2. Let them know that in the next lesson, each student pair will share their question with the rest of the class.



Bear Behavior Bingo

  1. Print a copy of the Katmai Junior Ranger Bear Behavior Bingo handout for each student or student pair.
  2. Have students mark the bingo sheet whenever they see one of the bear behaviors and actions on the live cam.
  3. Tell them that if they get 4 in a row (up, down, or diagonal), they’ve gotten a bingo!