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Sunday crab lab! Wear: warm clothes, bring gloves and RUBBER BOOTS. If raining, bring umbrella.

Sunday crab lab! Wear: warm clothes, bring gloves and RUBBER BOOTS. If raining, bring umbrella. Transport on Sunday : Either arrive before 12 noon at Spanish Banks, or 11:50 latest in Zoology courtyard. Monday : meet in Zoology courtyard at 1pm. Snow Goose. La P érouse Bay.

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Sunday crab lab! Wear: warm clothes, bring gloves and RUBBER BOOTS. If raining, bring umbrella.

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  1. Sunday crab lab! Wear: warm clothes, bring gloves and RUBBER BOOTS. If raining, bring umbrella. Transport on Sunday: Either arrive before 12 noon at Spanish Banks, or 11:50 latest in Zoology courtyard. Monday: meet in Zoology courtyard at 1pm

  2. Snow Goose La Pérouse Bay

  3. Herding flightless geese into a “keyhole” net

  4. Recording which birds are marked, and marking new birds

  5. Goose biologist Goose leg bands

  6. LPB Colony size Year

  7. Mark recapture lectures • Petersen method • Schnabel method • Schumacher-Eschmeyer • Jolly Seber Closed population Open population Overview of methods to help your reading of Krebs Chp 2

  8. Closed populations No individuals enter or leave the population between surveys Survey 2 Survey 1

  9. Open populations Individuals enter or leave the population between surveys Survey 2 Survey 1

  10. What makes a population closed? • Dispersal barriers • Philopatry • Large surveyed area • Slow reproductive/death rate • Short time between surveys

  11. What type of population are the snow geese?

  12. Petersen method: Closed population Survey 1: Survey 2: Catch several animals Catch C animals Count recaptures (R) Mark all M animals Return animals to population Return animals to population

  13. Survey 2: Survey 1: M = 12 C = 15 R = 4

  14. M = R N C N = M C R What is the total population size (N)? Note that the proportion marked in the population equals the proportion marked in the 2nd sample M = 12 C = 15 R = 4

  15. N = 13 * 16 5 -1 What is the total population size (N)? Note that the proportion marked in the population equals the proportion marked in the 2nd sample N = (M+1) (C+1) (R+1) -1 M = 12 C = 15 R = 4

  16. When would Petersen give you a bad estimate? • Population not closed • Marked animals likely to be re-trapped • Marked animals likely to die • Marks fall off

  17. Survey 2 Survey 3 Survey 4 Survey 5 Schnabel method: closed population Survey 1 Essentially, Petersen estimates on multiple surveys

  18. Survey t: Catch Ct animals Record Rt recaptures Mark Ut unmarked animals Return animals to population Schnabel method: closed population

  19. Schnabel method: closed population Survey t: Catch Ct animals What’s the relationship between Ct, Rt, and Ut ? Record Rt recaptures Mark Ut unmarked animals Ct = Rt + Ut Return animals to population

  20. Schnabel method: example How many individuals marked by beginning of time 5?

  21. Schnabel method: example How many individuals marked by beginning of time 5?

  22. Schnabel method: example Σ = 58

  23. Schnabel method: example In general: Mt = U1 + U2..Ut-1 Σ = 58

  24. Schnabel formulas: Marked > 10% of population N = Σ (Ct Mt) Σ Rt N = Σ (Ct Mt) Σ Rt+1 Marked < 10% of population ( just weighted average of Petersen estimates!)

  25. Schnabel method: example 0 48

  26. Schnabel method: example 0 48 Σ = 2060 Σ = 22

  27. Schnabel method: example N = Σ (Ct Mt) = 2060 = 94 Σ Rt 22 0 48 Σ = 2060 Σ = 22

  28. Schnabel method: example What proportion of total population marked by end? 0 48 Σ = 2060 Σ = 22

  29. R = 1 * M C N Scumacher-Eschmeyer method (for Schnabel experiment) N = C M R y = mx + b

  30. R = 1 * M C N Scumacher-Eschmeyer method (for Schnabel experiment) N = C M R R C Slope = ? M

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