Ecological census techniques : a handbook / edited by William J. Sutherland.

table of contents

List of contributors page xii
Preface xiv
1 Planning a research programme 1
William J. Sutherland
Introduction: reverse planning 1
What is the specific question? 2
What results are necessary to answer the questions? 2
What data are needed to complete these analyses? 4
What protocol is required to obtain these data? 4
Can the data be collected in the time available? 5
Modifying the planning in response to time available 7
Creating data sheets 8
Start and encounter reality 10
2 Principles of sampling 11
Jeremy J. D. Greenwood and Robert A. Robinson
Before one starts 13
Objectives 13
Know your organism 13
Censuses and samples 13
Know the reliability of your estimates 14
Performing the calculations 16
Sampling – the basics 18
Defining sample units and the sampling frame 18
The need for replication 18
Ensuring that samples are representative 19
Deviations from random 21
The shape and size of sampling units 23
Estimation of means and total population sizes 25
The layout of samples 33
Cluster sampling 33
v
vi Contents
Multi-level sampling 38
Stratified sampling 43
Adaptive sampling 51
Repeated counts at the same site 58
Comparing two or more study areas 62
Modelling spatial variation in numbers 65
Surveillance and monitoring 67
The difference between surveillance and monitoring 67
Monitoring and adaptive management 67
Sampling design for surveillance 71
Describing long-term changes 72
Alerts and indicators 77
Planning and managing a monitoring programme 83
References 85
3 General census methods 87
Jeremy J. D. Greenwood and Robert A. Robinson
Introduction 89
Complete counts (1): general 90
Not as easy as it seems 90
Sampling the habitat 90
Attempted complete enumeration 91
Complete counts (2): plotless sampling 91
Sample counts (1): mark–recapture methods 94
Fundamentals of mark–recapture 94
The two-sample method 100
Multiple recaptures in closed populations 102
Multiple recaptures in open populations 119
The robust model 128
What area does a trapping grid cover? 128
Sample counts (2): some other methods based on trapping 129
The removal method 129
The change-in-ratio method 130
Simultaneous marking and recapture: the method of Wileyto et al. 132
Continuous captures and recaptures: the Craig and du Feu method 132
Passive distance sampling 136
Sampling from the whole area 136
Sample counts (3): ‘mark–recapture’ without capture 136
Marking without capture 136
Individual recognition without capture 136
Contents vii
The double-observer method 137
The double-survey method 140
Subdivided point counts 140
Sample counts (4): N-mixture models 140
Sample counts (5): distance sampling 141
General 141
Line transects 145
Point transects 148
Passive distance sampling 148
Sample counts (6): interception methods 152
Point quadrats 152
Line intercepts (cover) 153
Line intercepts (counts) 153
Sample counts (7): migrating animals 154
Continuous migration 154
Stop-over sites 155
Population indices 155
The idea of an index 155
Overcoming variation in the index ratio 158
Double sampling 168
Frequency of occurrence 168
Basics 168
Managing the methodology 174
Sampling strategy and statistical analysis for frequency of occurrence 176
Subdivision of samples 177
Appendix: software packages for population estimation 181
Capture–recapture: closed populations 181
Capture–recapture: open populations 182
Ring-recovery models 182
Multi-state models 183
Observation-based methods 183
References 183
4 Plants 186
James M. Bullock
Introduction 186
Counts 188
Dafor 189
Quadrats 189
Point quadrats 194
viii Contents
Transects 196
Mapping terrestrial vegetation 197
Mapping aquatic vegetation 200
Seed traps 201
Sampling of seedbanks 204
Phytoplankton 207
Benthic algae 209
Marking and mapping individuals 210
References 212
5 Invertebrates 214
Malcolm Ausden and Martin Drake
Introduction 214
Direct searching and collecting 216
Trapping 216
Extraction from the substrate 216
Storing, killing and preserving invertebrates 219
Searching and direct observation (terrestrial and aerial) 220
Pitfall traps 222
Sweep netting 225
Vacuum sampling 226
Beating 228
Fogging 228
Malaise traps 229
Window or interception traps 231
Water traps 232
Light traps 234
Other aerial attractants and traps 236
Terrestrial emergence traps 237
Digging and taking soil cores 238
Litter samples and desiccation funnels 239
Searching and direct observation (aquatic) 240
Pond netting 241
Cylinder samplers 242
Aquatic bait traps 243
Aquatic emergence traps 243
Digging, taking benthic cores and using grabs 244
Kick sampling 245
References 247
Contents ix
6 Fish 250
Isabelle M. Cotˆ e´ and Martin R. Perrow
Introduction 250
Bankside counts 251
Underwater observations 253
Electric fishing 254
Seine netting 257
Trawling 260
Lift, throw and push netting 263
Hook and lining 265
Gill netting 266
Trapping 269
Hydroacoustics 271
Visual estimates of eggs 273
Volumetric estimates of eggs 273
Plankton nets for catching eggs 274
Emergence traps for eggs 275
References 275
7 Amphibians 278
Tim R. Halliday
Introduction 278
Recognising individuals 280
Detection probability 280
Drift netting 285
Scan searching 286
Netting 287
Trapping 288
Transect and patch sampling 289
Removal studies 290
Call surveys 290
Using multiple methods 291
Recording other data 293
References 293
8 Reptiles 297
Simon Blomberg and Richard Shine
Introduction 297
Hand capturing 297
Noosing 301
x Contents
Trapping 302
Marking individuals 305
References 306
9 Birds 308
David W. Gibbons and Richard D. Gregory
Introduction 308
Listing methods 311
Timed species counts 313
Territory mapping 314
Transects 319
Line transects 320
Point counts or point transects 324
Correcting for differences in detection probabilities 326
Capture techniques 328
Catch per unit effort 328
Capture–mark–recapture 330
Counting nests in colonies 331
Counting roosts 335
Counting flocks 336
Counting migrants 337
Indirect methods of censusing 339
Dropping counts 339
Footprints and tracking strips 340
Response to playback 341
Vocal individuality 342
References 344
10 Mammals 351
Charles Krebs
Introduction 351
Nesting or resting structures 354
Bat roosts and nurseries 354
Line transects 356
Aerial surveys 358
Individual recognition 359
Counting calls 360
Trapping 360
Counting dung 363
Feeding signs for herbivores 364
Contents xi
Counting footprints and runways 364
Hair tubes and hair catchers 365
Counting seal colonies 366
References 367
11 Environmental variables 370
Jacquelyn C. Jones, John D. Reynolds and
Dave Raffaelli
Introduction 370
Wind and water flow 371
Wind 372
Water flow 372
Other kinds of water movement 374
Rainfall 374
Temperature 374
Humidity 375
pH 376
Duration of sunshine 377
Slope angles and height above shore 377
Light 378
Aquatic light 380
Water turbidity 380
Conductivity 381
Salinity 382
Preamble to water chemistry 383
Dissolved oxygen 385
Nitrogenous compounds 389
Phosphorus compounds 396
Water-testing kits 399
Soil and sediment characteristics 399
Redox potential 405
Oxygen in soils and sediments 405
References 406
12 The twenty commonest censusing sins 408
William J. Sutherland
Index 411