Today: Grizzly Bears Tours this week Toxic Garbage Island movie W 4/21 at 5pm in JES A121A Ecological Interconnections We are only one of millions of species on earth. Grizzly Bears Grizzly bears are big. 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 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? mostly eat The Digestive System Different mouth and teeth structures can tell about an animals diet Fig 41.18 Grizzly bear teeth Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 54 cat dog grizzly panda Different teeth and diets Carnivores have a short digestive system Herbivores have a long digestive system Fig 41.19 HumansBears Both humans and grizzly bears are omnivores. Our digestive systems can tell us about our ancestors. Fig 41.19 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 (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. There is not much to eat in winter... Bears from temperate climates sleep over the winter in a den. (not hibernation) 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 59 Grizzly reproduction winter fall summer spring young born den w/ mother juveniles on own Female Grizzly Bear reproductive cycle Females are not fertile when caring for offspring fertiliz- ation SpringSummerFall Winter (in den) Birth year copulation delayed implantation gestationbirth 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 young born den w/ mother juveniles 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 Historical Grizzly Bear range Current Grizzly Bear range Habitat destruction and hunting have severely decreased grizzly populations in the U.S. 63 mi 54 mi 466 mi of roads 950 mi of backcountry trails 97 trailheads 287 backcountry campsites Yellowstone NP Yellowstone Grizzly Bear population increases Yellowstone NP is not big enough to support a viable grizzly bear population 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 Next: Ecology Introduction Tours this week Toxic Garbage Island movie W 4/21 at 5pm in JES A121A