Counting Animals

The AfESG is proud to bring you Mike Norton-Griffiths's Counting Animals (2nd edition, 1978), the classic handbook on population survey methods for African mammals.

The online edition of Counting Animals is in PDF format, and you must have the free Adobe Acrobat Reader in order to view it. This site uses byte-serving technology, which means that by following the links below you will jump to the desired part of the handbook without having to download the entire pdf file. The document was scanned and then run through an optical character recognition engine that retains the exact look of the original while making the document searchable.

Counting animals has been digitized and made available on the web with permission from the African Wildlife Foundation. The AfESG would like to express its gratitude to the Conservation Development Centre for initial scanning, Howard Frederick for availing the scanned document to the AfESG, Philip Muruthi at AWF for his keenness on seeing Counting Animals on the web, and to Mike Norton-Griffiths - who is currently working on an updated version of this handbook - for supporting this effort.

Foreword by J.J.S. Grimsdell, Series Editor

TABLE OF CONTENTS

SECTION 1 INTRODUCTION TO COUNTING ANIMALS 1

SECTION 2 THE PRINCIPLES OF A SAMPLE COUNT 9

2.1 Introduction 9

2.2 Calculating the Sample Mean and the Sample Estimate Ŷ 12

2.3 Calculating the 95% Confidence Limits of Ŷ 14

SECTION 3 RANDOM NUMBERS, RANDOM SAMPLES AND MAPS 17

3.1 Random Number Tables 17

3.2 Simple Random Samples 18

3.3 Choosing Random Points Along a Line 18

3.4 Choosing Random Points in Space 19

3.5 Maps 19

SECTION 4 METHODS OF AERIAL SAMPLE COUNTING 22

4.1 Introduction 22

4.2 Aerial Transect Sampling 22

4.3 Aerial Quadrat Sampling 23

4.4 Aerial Block Sampling 24

4.5 Comparisons Between the Three Methods 24

SECTION 5 DESIGNING AN AERIAL SAMPLE COUNT 29

5.1 Introduction 29

5.2 Defining the Census Zone 29

5.3 Choosing a Sampling Method 30

5.4 Reducing Sample Error 31

5.5 Avoiding Bias and Errors 38

5.6 Accuracy or Precision? 41

5.7 Costs 42

SECTION 6 PRACTICAL ASPECTS OF AERIAL SAMPLE COUNTING 45

6.1 Introduction 45

6.2 Choice of Aircraft 45

6.3 Transect Sampling - General Flight Planning 47

6.4 Transect Sampling - Piloting 50

6.5 Transect Sampling - Observing 53

6.6 Block/Quadrat Sampling 61

6.7 An 'Ideal' Aircraft/Crew 64

SECTION 7 WORKING UP THE RESULTS FROM AN AERIAL SAMPLE COUNT65

7.1 Introduction 65

7.2 The Stages in the Analysis 66

7.3 Multi-Species Aerial Block Counts 75

7.4 The Method for Equal Sized Sampling Units 75

7.5 Stratified Sample Counts 75

7.6 Some Complications 75

7.7 Correcting for Total Bias 79

7.8 Methods for Comparing and Merging Estimates 80

SECTION 8 VARIOUS SAMPLING PROBLEMS 83

8.1 Introduction 83

8.2 Lack of Good Maps 83

8.3 Stratifying out Large Herds 84

8.4 Stratifying After the Event 85

8.5 Completely Photographic Methods 85

8.6 Cattle Counts 86

SECTION 9 AERIAL TOTAL COUNTS 87

9.1 Introduction 87

9.2 The Method Used for Total Counting the Serengeti Buffalo 88

9.3 The Magnitude and Consistency of Biases 89

9.4 The Design of a Total Count 91

9.5 Applications for Total Counts 92

SECTION 10 GROUND COUNTING FROM VEHICLES 94

10.1 Introduction 94

10.2 Block Counts and Total Counts from Vehicles 94

10.3 Vehicle Transect Counts 95

10.4 Problems Concerning Strip Width in Vehicle Transect Counts 96

10.5 Road Counts 100

10.6 Discussion 103

SECTION 11 INDIRECT METHODS OF COUNTING ANIMALS 106

11.1 Introduction 106

11.2 Mark-Release-Recapture (or Capture-Recapture) Methods 106

11.3 Change in Ratio Methods 106

11.4 Pellet Counts 107

11.5 Broadcasting Tape Recorded Calls 107

REFERENCES 108

APPENDICES

1 THE STUDY OF MOVEMENTS AND DISTRIBUTION 112

2 TRAINING OBSERVERS 126

3 MORE ABOUT COUNTING BIAS 131

4 OPERATIONAL PROCEDURES AND CHECK SHEETS FOR CENSUSES 135