Numbers From the Den: teacher key

Grizzly Bears, grade 10 edition, written for 10th grade. Heart scans, tracking collars and hair collected at bear rubs tell scientists how bears sleep, eat and how their numbers change.

Read the book. Print this page for the key.

Questions and answers

1. What is echocardiography, as used in the study?
   • Ultrasound of the heart (answer)
   • A tracking collar
   • A hair trap
2. How did the heart rate of the 13 young bears change from late hibernation to early summer?
   • It averaged 71 beats a minute, then 26
   • It averaged 26 beats a minute, then 71 (answer)
   • It stayed at 26
3. When did the bears enter the den in the three-winter study?
   • When the trout began to spawn
   • When the moths arrived
   • When snow arrived and the air temperature reached 0 degrees Celsius (answer)
4. Activity, heart rate and body temperature began to fall weeks before the den. What does this show?
   • The bears' bodies started changing before they entered the den (answer)
   • The bears were sick
   • The bears had already left the den
5. How do USGS scientists estimate how fast a grizzly population is growing?
   • By counting dens from the air
   • By collecting hair at natural bear rubs (answer)
   • By weighing salmon
6. What was first seen in 1986?
   • A bear eating trout
   • A bear in a den
   • A radio-collared grizzly feeding on moths (answer)

Words

• echocardiography: heart ultrasound
• metabolism: body energy use
• spawn: lay eggs