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Predator-Prey Relationships

Predator-Prey Relationships. What are Predators?. What are predators?. Carnivory Herbivory (plants vs. seeds) Cannibalism Parasitism. Human Attitudes and Predators. Humans perspectives Human persecution. OVERCOMING HISTORY. Fairy Tales: “Little Red Riding Hood”

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Predator-Prey Relationships

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  1. Predator-Prey Relationships What are Predators?

  2. What are predators? • Carnivory • Herbivory (plants vs. seeds) • Cannibalism • Parasitism

  3. Human Attitudes and Predators • Humans perspectives • Human persecution

  4. OVERCOMING HISTORY • Fairy Tales: “Little Red Riding Hood” • “ The Three Little Pigs” • Wolf attacks on humans

  5. OVERCOMING HISTORY • Old attitudes die hard • Urban residents and predators

  6. Predation in Natural Communities • Almost all animals have significant predators- exceptions are: • Herbivores:Top predators: • Bison Grizzly • Elephant Lions • Rhinos Polar bear • Hippos Killer Whale

  7. Predation in Natural Communities • Do predators regulate prey populations? • Ecosystems and predator communities

  8. Major predators of the Arctic NWR Wolf Polar Bear Grizzly Ermine Arctic fox Snowy Owl

  9. Predator-Prey RelationshipsResponse to Prey 1. Functional Response Tendency of the predator to eat more of a prey species as the prey become more abundant

  10. Predator-Prey RelationshipsFunctional Response

  11. Predator-Prey RelationshipsResponse to Prey Numerical Response Number of predators increases with an increase in the density of prey animals

  12. Predator-Prey RelationshipsNumerical Response(Buckner and Turnock 1965)

  13. Annual cycle of a prey population 100 Energy shortages Energy shortages Accidents Disease Accidents Predation Percentage of Population Disease Predation J F M A M J J A S O N D

  14. Population Cycles Snowshoe hare Lynx No. in thousands Years

  15. Muskrat and Mink Paul Errington’s Classic study of muskrat populations

  16. Muskrat info Habitat: wetlands, especially marshes Food: marsh vegetation Predators: mink, coyotes, great horned owls eagles

  17. Muskrat and predation • Observations: • Predation and population size • Predation and individual vulnerability

  18. Muskrat Behavior • Population size and social intolerance • Population size and social outcasts

  19. Muskrat and Mink interactions:Conclusions • Social interactions may be more important than predation in limiting numbers of prey. • The total effect of predation cannot be assessed simply by counting the number of animals killed by predators (selectivity)

  20. Isle Royale • Size: 45 miles long x 9 miles wide • Protection: National Park established in 1940 Wilderness designation in 1976 National Biosphere Reserve 1980 • A location of a long term study of the relationships between the moose and gray wolf

  21. Historically, two large ungulates occupied Isle Royale: Woodland Caribou Moose

  22. Caribou Population • Settlers arrived in late 19th century • Hunted caribou • Responsible for fire, and forest cutting Fires resulted in changing old-growth coniferous forests to younger deciduous forests Caribou became extinct on the island

  23. Moose History • Fires resulted in changing old-growth forests to younger forests • Around 1910, moose came across the ice from Minnesota and became established • Moose outcompeted woodland caribou; island was better habitat for the moose after fires (early succession, deciduous trees)

  24. Wolfe Population • Winter 1949, gray wolf arrives by crossing ice from mainland

  25. Current Populations on Isle Royale Winter 2000-2001 Moose 850 Wolf 29

  26. Present Wolf Population on Isle Royale The wolf population is now divided into 2 territories, rather than the 3 that have been present for some time: West Pack: gone Middle Pack: 12 East Pack: 10 Roaming animals: 5-7

  27. Food Chain Wolf Moose Small rodents Beaver Grouse berries Vegetation

  28. Wolf Response to Moose • Functional Response: lots of moose, • Possible because wolfs are cooperative hunters

  29. Wolf Response to Moose • Numerical Response: lots of moose, • wolves reproduce well • Immigration is unlikely since it depends on Lake Superior freezing.

  30. Moose Response to the Wolf • Wary; formidable prey • Moose in good condition can withstand an attack by a wolf pack. • Can’t turn and run: wolf can sever back leg tendon which renders the moose helpless.

  31. Moose Response to the Wolf • most vulnerable moose are the very young and the old (infirm) • most killed moose show signs of malnutrition and disease (i.e. they are more vulnerable) • Males most vulnerable: go into winter in relatively poor shape because of rut

  32. Wolf Population Three major factors that control the wolf population: 1. Moose numbers 2. Linear dominance hierarchy in wolf population 3. Genetic diversity (inbreeding effects)

  33. For more Information www.admin.intu.edu/urel/PressRelease/feature/wolves/wolf. Html www.timberwolfinformation.org/programs/awp/awpi/Isle.htm http://midwest.fws.gov/wolf/proposal/nr_71100.htm Or simply type in key words: “wolf”, “timber wolf”, or “Isle Royale”

  34. How Does The Prey Fight Back

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