1. Population Reproduction, births, natality (B) Mortality, death (D) Emigration (E) Immigration (I) Population growth

2. Adult survival, juvenile survival, and fecundity are what we need to estimate λ, the intrinsic population growth rate. Sink / declining Stable population Source/ growing populations

3. From Oleyar et al. (in prep)

4. No obvious response in growth rate by landscape.

5. Declining λ outside of reserves?

6. Possible sink during development for some species followed by recovery as subdivision ages?

7. How do these projections match up with what we see out there? Winter Wren numbers high and ‘stable’ in reserves, low and/or declining elsewhere Robin numbers ‘stable’ but low in reserves, highest in developed residential areas Are developed landscapes ecological traps for Robins?

8. Populations fluctuate due to Density dependent factors –Ex: Predation, competition, habitat availability –change population growth in predictable ways –N is driven by population density Density independent factors –Random or Stochastic events –Ex. Weather, accidents –Breeding 14 aug 2007

9. time # of Animals (N) Definitions Population regulation: the tendency of population sizes to stay within a certain range

10. time # of Animals (N) k Carrying capacity (k): the number of organisms that can be supported by a given area; the actual number of organisms fluctuates near this Carrying capacity

11. Population fluctuations Carrying capacity (k) Classic growth curve, unlimited resources Classic growth curve, limited resources (k) time NN k

12. Example of unlimited growth: Australian rabbit (European hare) 1859: 24 hares introduced (for human food?) 1865: over 20,000 hares were harvested, actual population much greater. Mid-1800’s to mid-1900’s: major problem with too many hares; caused habitat destruction and reduction in native mammals 2000: still present, local problems Population fluctuations

13. No rabbits Rabbits exceeded k Rabbit-proof fence Carrying capacity

14. High food addition Low food addition No food added Shaded area is winter Townsend’s vole Population regulation: food

15. Population cycles: Ex. peaks in lynx populations show time lag behind peaks in snowshoe hare populations Population size Snowshoe hare Lynx Time (years) Population regulation: food

16. Population regulation: climate

17. Competition – demand by 2 or more individuals of the same or different species for a common resource Between 2 individuals of same species: Intraspecific Between 2 individuals of different species: Interspecific Limited supply of resource: Exploitation Not limited but interaction detrimental: Interference Population regulation: competition

18. Inter- or Intraspecific competition? Exploitation or Interference competition?

19. Population regulation: competition

20. Niche: an n-dimensional hypervolume which includes the range of biological and physical conditions under which an organism can exist, including the resources that an animal must exploit for growth and reproduction A portion of the feeding niche of the Blue-gray Gnatcatcher (Smith & Smith 1998) Prey length (mm) Foraging height (m) Niche

21. Food sources (both what and where) Nest or Den sites Interspecific competition can lead to resource partitioning, and expression of a ‘realized niche’ versus a species ecological niche. Interspecific Competition

22. Predator-Prey Relationships

23. What are predators? Animals that kill and eat other animals (prey) At or near the top of the trophic pyramid

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

26. Predation in Natural Communities Almost all animals have significant predators- exceptions are: Herbivores:Top predators: BisonGrizzly bear ElephantLions Rhinoceros Polar bear Hippopotamus Killer Whale

27. Human Attitudes and Predators Human perspectives –Little Red Riding Hood –The Three Little Pigs Human persecution

28. Why? Domestication of animals Protection Entertainment

29. Overcoming History Old attitudes die hard Urban residents and predators

30. Predator-Prey Relationships Response to Prey Functional Response Tendency of the predator to eat more of a prey species as the prey become more abundant

31. Predator-Prey Relationships Functional Response

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

33. Predator-Prey Relationships Numerical Response (Buckner and Turnock 1965) High Density (N/km 2 ) Low Density (N/km 2 ) Sawfly Juveniles5,280,00098,800 Sawfly adults507,50011,600 Birds58.131.1

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

35. Population Cycles

36. Adaptations to cyclical prey cycle? DispersalPrey switchReproduction

37. Isle Royale

38. 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

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

40. Isle Royale Settlers arrived in late 19 th century Responsible for fire and forest cutting Moose cross ice from Minnesota and establish early 20 th century Fires change old-growth coniferous forests to younger deciduous forests Moose outcompete woodland caribou Caribou became extinct on the island Wolves arrive 1950 by crossing ice

42. Wolf Response to Moose Functional Response: lots of moose Possible because wolves are cooperative hunters Numerical Response: lots of moose wolves reproduce well Immigration is unlikely since it depends on Lake Superior freezing (uncommon)

43. 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

44. 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)