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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 summer fertilization winter young born spring Females are not fertile when caring for offspring Grizzly Bear Reproduction Spring Summer Birth year copulation delayed gestation implantation 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) Offspring Adolescent with mom year (lactation) Offspring on own Fall Winter (in den) 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 summer fertilization winter young born 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...