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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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Presentation Transcript
slide1

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

slide2

Snow Goose

La Pérouse Bay

slide5

Goose biologist

Goose leg bands

mark recapture lectures
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

closed populations
Closed populations

No individuals enter or leave the population between surveys

Survey 2

Survey 1

open populations
Open populations

Individuals enter or leave the population between surveys

Survey 2

Survey 1

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

slide13

Survey 2:

Survey 1:

M = 12

C = 15

R = 4

slide14

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

slide15

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

when would petersen give you a bad estimate
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
schnabel method closed population

Survey 2

Survey 3

Survey 4

Survey 5

Schnabel method: closed population

Survey 1

Essentially, Petersen estimates on multiple surveys

schnabel method closed population1

Survey t:

Catch Ct animals

Record Rt recaptures

Mark Ut unmarked animals

Return animals to population

Schnabel method: closed population
schnabel method closed population2
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

schnabel method example
Schnabel method: example

How many individuals marked by beginning of time 5?

schnabel method example1
Schnabel method: example

How many individuals marked by beginning of time 5?

schnabel method example3
Schnabel method: example

In general: Mt = U1 + U2..Ut-1

Σ = 58

schnabel formulas
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!)

schnabel method example5
Schnabel method: example

0

48

Σ = 2060

Σ = 22

schnabel method example6
Schnabel method: example

N = Σ (Ct Mt) = 2060 = 94

Σ Rt 22

0

48

Σ = 2060

Σ = 22

schnabel method example7
Schnabel method: example

What proportion of total population marked by end?

0

48

Σ = 2060

Σ = 22

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