Putting Animal Physiology and Ecology together Grizzly Bears

Putting Animal Physiology and Ecology together… Grizzly Bears

Ecological Interconnections

We are only one of millions of species on earth.

Why are species going extinct? Fig 55. 6

For some species it is already too late. . . FEWER THAN 100 REMAIN EXTINCT FEWER THAN 100 REMAIN

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

Grizzly Bears

Grizzly bears are big.

How are bears related to each other? Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 28

12, 000 years ago: the grizzly ancestor shortfaced bear Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 15

Short-faced vs grizzly bears Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 17 and 23

How closely related are these bear species? Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 28

Grizzly-Polar bear hybrid (from a zoo) Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 200

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

Fig 43. 5 The Digestive System

Different mouth and teeth structures can tell about an animal’s diet

Different mouth and teeth structures can tell about an animal’s diet

Grizzly bear teeth

Carnivores have a short digestive system Herbivores have a long digestive system

Bears Both humans and grizzly bears are omnivores. Our digestive systems can tell us about our ancestors. Humans

Different teeth and diets grizzly cat dog panda Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 54

About 75% of their diet is plants

They also eat carrion.

Some grizzlies are excellent predators, but most eat carrion. Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 85

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

There is not much to eat in winter. . .

Bears from temperate climates sleep over the winter in a den. (not hibernation)

Grizzlies have an amazing ability to gain and lose weight. Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 62 and 63

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

Female Grizzly Bear reproductive cycle juveniles on own den w/ mother fall winter young born summer fertilization spring Females are not fertile when caring for offspring

Grizzly Bear Reproduction Fall Winter (in den) Spring Summer Birth year copulation delayed implantation gestation Juvenile year 1 Offspring with Offspring mom with. Offspring mom den wi (lactation) Juvenile year 2 Offspring with Offspring mom with. Offspring mom den wi (lactation) Adolescent Offspring with mom Offspring on own year (lactation) birth

Grizzly cubs are born in the den and are very small (~1 lb) Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 58

Female Grizzly Bear reproductive cycle juveniles on own den w/ mother fall winter young born summer fertilization spring Females are not fertile when caring for offspring

Female bears are very protective of their young Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 76

Infanticide: males will try to kill young so that mother will become fertile Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 77

Human-Bear Interactions

Current Grizzly Bear range Historical Grizzly Bear range

Hunting Grizzlies

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

Studying Grizzlies CB 55. 11

Yellowstone NP 63 mi 54 mi • 466 mi of roads • 950 mi of backcountry trails • 97 trailheads • 287 backcountry campsites

Yellowstone Grizzly Bear population increases

Where do grizzly bears fit? Are they important? How much of our resources should we share with grizzly bears?

Animal behavior is unpredictable and inexplicable Bears (1993) Ian Stirling et al. , Weldon Owen Pty Ltd pg 231

Next: Ecology. . .