Putting Animal Physiology and Ecology together… Grizzly Bears

Ecological Interconnections

CB 54.2Interconnections

We are only one of millionsofspeciesonearth.

SpeciesintroductionsHunting

HabitatDestructionOther

39%

23%

36%

2%Why are species going extinct?

Nearly Extinct Species:maybe only 100 individuals exist

CB 55.3

Habitat loss and fragmentation has been extensive in the US due to human modification of the environment

What responsibility do we have for the well-being of non-humans?

Under what circumstance should we put the needs of non-humans above the needs of humans?

Grizzly Bears

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 28

How are bears related to each other?

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 15

12,000 years ago: the grizzly ancestor short-faced bear

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 17 and 23

Short-faced vs grizzly bears

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 28

How closely related are these bear species?

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 200

Grizzly-Polar bear hybrid (from a zoo)

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 78

Grizzly bears live most of their lives alone

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 78

Grizzly bears live most of their lives alone.

What do they do?

About 75% of their diet is plants

They also eat carrion.

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 85

Some grizzlies are excellent predators, but most eat carrion.

Bears from temperate climates sleep over the winter in a den.

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 62 and 63

Grizzlies have an amazing ability to gain and lose weight.

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 186

Grizzlies constant search for food can lead to conflicts with humans.

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 215

Grizzlies constant search for food can lead to conflicts with humans.

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 54

cat

dog

grizzly

panda

Different teeth and diets

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 59

Grizzly reproduction

Spring Summer Fall Winter

(in den)

Birth

year

copulation delayed implantation

gestation birth

Juvenile

year 1

Offspring with mom

(lactation)

Offspring with mom

(lactation)

Offspring with mom

(lactation)

Offspring den with mom

(lactation)

Juvenile

year 2

Offspring with mom

(lactation)

Offspring with mom

(lactation)

Offspring with mom

(lactation)

Offspring den with mom

(lactation)

Adolescent

year

Offspring with mom

(lactation)

Offspring on own

Grizzly Bear Reproduction

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 58

Grizzly cubs are born in the den and are very small (~1 lb)

winter

fall

summer

spring

youngborn

den w/motherjuveniles

on own

Female Grizzly Bear reproductive cycle

Females are not fertile when caring for offspring

fertiliz-ation

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 76

Female bears are very protective of their young

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 77

Infanticide: males will try to kill young so that mother will become fertile

Human-Bear Interactions

Historical Grizzly Bear range

Current Grizzly Bear range

Hunting Grizzlies

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 216

Hunters

Studying Grizzlies

CB55.11

63 mi

54 mi

•466 mi of roads •950 mi of backcountry trails•97 trailheads•287 backcountry campsites

Yellowstone NP

CB 55.12

Yellowstone Grizzly Bear population increases

CB 55.16

Artificial corridors allow animals to cross fragmented areas

CB 55.16

CB 55.18

Where do grizzly bears fit?

Are they important?

How much of our resources should we share with grizzly bears?

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 231

Animal behavior is unpredictable and inexplicable