Chapter 4: Abundance

Question 1

population

Answer 1

a collection of individuals of a species in a defined area, for which it is meaningful to refer to abundances, birth and death rates, sex ratios, and age structure

Question 2

BIDE equation

Answer 2

Nt+1 = Nt + Bt + It - Dt - Et

Question 3

density

Answer 3

if abundance is scaled per unit area

Question 4

incomplete detection

Answer 4

since we cannot count them all, we have to deal with it

Question 5

estimate of abundance variable

Answer 5

N

Question 6

estimate of abundance formula

Answer 6

N = count / p

Question 7

census

Answer 7

complete count

Question 8

the value of p is often

Answer 8

< 1

Question 9

indices

Answer 9

• not sampling actual animals
• cannot estimate p

Question 10

indices: to rely on for abundance

Answer 10

known relationship between index and abundance

Question 11

indices: to rely on for trend

Answer 11

constant relationship between index and abundance

Question 12

transect methods

Answer 12

count animals along a line

Question 13

types of transect methods

Answer 13

• distance sampling
• replicated counts
• viewshed methods

Question 14

distance sampling

Answer 14

• p decreases with distance
• detection function can be estimated

Question 15

key assumptions of distance sampling

Answer 15

• all animals directly on the line are seen
• animals are counted only once and do not move before being sighted
• perpendicular distances are measured exactly

Question 16

example of sightings from a line, from a center of a circle

Answer 16

point counts of birds

Question 17

CMR

Answer 17

capture-mark-recapture

Question 18

two types of CMR models

Answer 18

• closed population models
• open population models

Question 19

closed population models

Answer 19

no change in the population during sampling period (no births, deaths, immigration or emigration)

Question 20

open population models

Answer 20

birth, death, immigration, and/or emigration may occur and be estimated

Question 21

mark-recapture concept

Answer 21

• sample animals from a population and mark them
• let the population mix
• resample the population
• count marked and unmarked animals

Question 22

Lincoln-Petersen: Foundational method

Answer 22

2 sessions
- 1 session to mark animals
- 1 session to estimate p

Question 23

n1

Answer 23

captured on 1st day

Question 24

n2

Answer 24

captured on 2nd day

Question 25

m2

Answer 25

captured on day 2 with marks

Question 26

p =

Answer 26

m2/n1

Question 27

N =

Answer 27

n1n2 / m2

Question 28

Lincoln Petersen - corrected for finite population sizes

Answer 28

N = [(n1 + 1)(n2 + 1) / (m2 + 1)] - 1

Question 29

assumptions of Lincoln Petersen

Answer 29

• population is closed
• marks are not lost
• all animals are equally likely to be captured

Question 30

all animals are equally likely to be captured

Answer 30

• time
• heterogeneity among individuals
• behavioral response

Question 31

violations of equal catchability

Answer 31

• temporal
• individual
• behavioral

Question 32

violations of equal catchability: temporal

Answer 32

conditions change over time

Question 33

violations of equal catchability: individual

Answer 33

each animal varies in capture probability

Question 34

violations of equal catchability: behavioral

Answer 34

trap happy vs trap shy

Question 35

additional points about L-P estimator

Answer 35

• animals do not have to be individually identified
• animals can be “captured” using different methods for the two sessions

Question 36

physically capturing and marking animals can be:

Answer 36

• stressful and/or dangerous for both study species ad researchers
• logistically difficult

Question 37

non-invasive “capture” and “mark” methods

Answer 37

• genetic methods
• photography/camera traps

Question 38

non-invasive “capture” and “mark” methods: genetic methods

Answer 38

• collect DNA from sloughed animal cells
• individual “marks” are highly variable genetic markers across several loci that can ID at individual levels

Question 39

non-invasive “capture” and “mark” methods: photography/camera traps

Answer 39

ID animals from natural markings