Aerial Surveys of Wildlife Transects "Abundance" (Lecture 6)

Question 1

What are some problems around aerial sampling?

Answer 1

1. Counting error (compensating)

2. Counting bias (most samplers tend to undercount)

Question 2

How can you increase precision with aerial sampling?

Answer 2

Optimal survey designs!

Stratification and high replication

Question 3

Describe Transect Sampling

Answer 3

Transects all perpendicular to the base line. One pass over every transect

Question 4

Describe Quadrat Sampling

Answer 4

Grid superimposed over sampling area

Quadrats are randomly selected

Question 5

Describe Stratified Sampling

Answer 5

Whole areas is stratified based on topographic features. Blocks are randomly selected.

Question 6

What is the basic idea behind the Probability Detection Function for line transect surveys?

Answer 6

the probability of detection of an animal decreases with distance from the transect line. The probability is equal to the area of the curve.

Question 7

What are some assumptions of the Haynes Estimator?

Answer 7

1. All organisms directly on the transect line are seen
2. Animals are fixed in the initial sitting position and do not move before detection, none are counted twice.
3. Distances and angles are measured exactly
4. Sighting of individuals are independent
5. The average sighting angle is 32.7 degrees

Question 8

What are some problems with aerial sampling?

Answer 8

1. Counting error
2. low precision
3. bias (tendency to undercount)

Question 9

What are the 3 types of aerial survey design?

Answer 9

1. Transect - Baseline with perpendicular transects
2. Quadrant - Grids randomly selected
3. Stratified - Whole area is stratified based on topographic features

Question 10

What is the basic idea behind the probability functions for line transect surveys?

Answer 10

The probability of detection of an animal falls off with distance from the transect line and the probability is equal to the total area under the curve.