WALLACE RESOURCE LIBRARY Lecture 04 – Terrestrial Survey Techniques in Guyana

WALLACE RESOURCE LIBRARYWALLACE RESOURCE LIBRARYLecture 04 – Terrestrial Survey Techniques Lecture 04 – Terrestrial Survey Techniques

in Guyanain Guyana


in Guyanain Guyana

This is an ‘example’ of a lecture that is given to A level students as part of their academic lecture series whilst on their expedition.It has been produced for the exclusive use of the lecturer conducting the series and is solely intended for educational purposes.Most of the material comes from Operation Wallacea sources and any other material that has been used has been credited (as far as is possible) to the appropriate author wherever possible.

This lecture is only to be used for EDUCATIONAL purposes.


in Guyanain Guyana


in Guyanain Guyana

Lecture overviewLecture overview

• Sampling methods– Replication– Mark Recapture methods– Distance Sampling (point counts and line

transects)– Patch occupancy

• Biodiversity monitoring methods– Trapping, netting etc

• Research design

General census techniquesGeneral census techniques

• True census involves counting all individuals in the population

• Rarely possible in a natural setting but part of the population can be studied using sampling

• Must ensure that samples are representative of the population

• Possible to extrapolate from representative samples to give a reliable estimate of the population as a whole

SamplingSampling strategiesstrategies

• Random sampling– Used when sampling the abundance or diversity of a given

species – all squares have equal chance of being sampled– Usually used for homogenous habitats

Random number tables used to decide which squares within the grid are sampled

Sampling strategiesSampling strategies

• Cluster sampling

– Used when the study area is very large and thus travel times to each randomly chosen sample point are large

Idea is to take multiple samples within each randomly chosen sample point

Sampling strategiesSampling strategies• Stratified sampling

– Individual habitats are rarely uniform, therefore random sampling may not cover all areas of a habitat equally

– Stratified sampling avoids missing out important areas of habitat by locating a proportional number of samples within each habitat type


Line transects– Transect routes may be used to create ‘pseudo-

random’ sampling locations, by following a straight line through a given strata.


• Replication

– Repeated counts at each sample site is a way of improving the precision of the estimate of the total population

– Estimated mean values less affected by outliers when sample size is large

– Repeated counts can also control for extraneous variables such as weather, time of day etc.

Mark-recapture samplingMark-recapture sampling

• Method

– Catch sample individuals from the population, mark them and release them

– Allow marked individuals to mix with general population

– Catch a second sample

% of marked individuals caught in second sample representative of % of those species present in the population

Mark-recapture samplingMark-recapture samplingMarking

– numbered rings most popular marking method for recognising individuals from a large population

– Combinations of coloured dots can be used for smaller populations

– Simple mark used if not necessary to recognize individuals

Mark-recapture samplingMark-recapture sampling

• Assumptions

– Marks on individuals are permanent or last for the duration of the study

– The population is closed so no new individuals join the population once the first individuals have been marked

Distance Sampling – Line Transects

Diagram by Sutherland, 2006

• Assumes that all animals on the transect line are detected and detectability of animals decreases when they are further away from the line

• As animals are encountered their perpendicular distance from the transect line is measured

• This model allows estimates of population density

Line transect distance samplingLine transect distance sampling

• Commonly used for monitoring large mammals

• Also for other species that range over large areas – game birds

• Also species that can be surveyed using transects - amphibians

• Suitable for species detected by vocalisation

• A simple and robust technique

Distance samplingDistance sampling

• Assumptions

– All animals 0 metres from the line are detected

– Animal locations are not affected by observers at the time distance is measured

– Density of animals is roughly constant in the area around the transect lines (on average)

Distance samplingDistance sampling

• Point counts

– Observers stays at a set point for a fixed period of time and records all individuals seen or heard during this time

– Often used to monitor birds– Most commonly done by

people who know the bird calls, usually done by experienced ornithologists

Patch occupancy samplingPatch occupancy sampling

• Identifies the total proportion of the survey area occupied by the target species

• Does not directly measure population density but produces values that positively correlate with density

• Used when studying rare or elusive animals and/or when visibility in the study area is poor (e.g. studying anoa in tropical forest)

Biodiversity monitoring methodsBiodiversity monitoring methods

• Trapping by conventional methods using traps:– Small mammals, large mammals, reptiles, amphibians,

invertebrates etc…

• Mist netting – bats and birds• Visual census – point counts, line transects• Camera ‘trapping’

Population monitoring – small mammalsPopulation monitoring – small mammals

• Usually surveyed using capture-mark-recapture (CMR)

• Range of methods for marking

• Baited traps placed along a transect line

– Tomahawk trap– Longworth trap– Sherman trap

Discussion 1 - DesigningDiscussion 1 - Designing research research

?Sutherland,W.J. 2006. Ecological census techniques.

• Is there a clear question?• Can it be answered within the time frame,

sample size, logistics etc?• Is the question even possible to answer?

– How does logging effect Jaguars?– What is the difference in relative abundance of

Jaguars in selectively logged and unlogged forests in central Guyana?

– Changes in Jaguar abundance before and after selective logging.

Research question/research objectivesResearch question/research objectives

• How do birds react to savannah fires?• The effect of savannah fires on bird diversity

and abundance.• How do savannah fires affect ground-nesting

birds?• The effect of savannah fires on ant diversity

and abundance.

Research question/research objectivesResearch question/research objectives

MethodsMethods

• Is the researcher ‘re-inventing the wheel’, or using more widely recognised methods.

• In some cases, data may be comparable across surveys and locations.

Sample sizeSample size

• Whether you are looking at presence/absense, or relative abundance, sample size MUST be suitable.

• Sample sizes for Jaguars will be much harder to obtain than sample sizes for ants.

Sample size & sample locationsSample size & sample locations

• What is a data point? – an item of factual information derived from

measurement or research

• So how do we know what the sample size actually is?

• Are the sample locations random?

Spatial artefacts in comparison studiesSpatial artefacts in comparison studies

• Comparisons of different treatments must be conducted across the same habitat.

• Sample sites should be placed in a suitable place (i.e. not too close to one-another), and a good distance from different treatments.– The distance depends on the home range of the

study species. Larger animals often have larger home ranges.

– Animals that fly have large home ranges to.

Control sitesControl sites

• Control sites are used to validate that changes can be attributed to the treatment.

• Control vs. pseudo-control.– Burned vs unburned = Unburned is Pseudo-

control, burned is treatment.

– Before burning = Treatment 1.– After burning = Treatment 2.– Need control – to ‘control’ for other factors.

Data analysisData analysis

• Has the researcher indicated what kind of data-analysis they will use?

• Statistics?• The best studies will have thought about the

analysis before the study design – reverse planning.

Discussion/Activity 2 -Quiz time!

• Using the bird identification pictures classify the birds into the most appropriate survey method for them:

– Line transect– Point count– Mist netting

Which sampling method?

IUCN category – LCThis species has an extremely large range, and hence does not approach the thresholds for Vulnerable. Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable. The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable.For these reasons the species is evaluated as Least Concern. Voice – Flight call a loud rasping screech, loudest and often with a stuttering effect at the end “g’RAA’A’AH!” Habitat/behaviour – Typically found in low lying forest, including varzea, swamp forest and palm swamps. Occasionally seen flying high over cleared areas and major rivers. Usually found in small flocks, but occasionally in large groups

Blue and yellow macaw Ara ararauna

Which sampling method?Hoatzin Opisthocomus hoazin

IUCN category – LCThis species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion. The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable. The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable. For these reasons the species is evaluated as Least Concern. Voice – Common calls include hoarse coughing and grunting sounds, also loud hisses. Habitat/behaviour – Always found over water, usually encountered perched low over still or slow moving water such as oxbow lakes or sluggish rivers.

Which sampling method?• IUCN category – LC• This species has an extremely large range, and hence does not

approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

• Voice – The great egret gives a variety of calls, including a low-pitched ‘kraak’ call that is given in flight, when disturbed, and as a threat call

• Habitat/behaviour – inland and coastal waterways

Great Egret Casmerodius

albus

Which sampling method?• IUCN category - LC• This species has an extremely large range, and

hence does not approach the thresholds for Vulnerable under the range size criterion. Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion.The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion. For these reasons the species is evaluated as Least Concern.

• Voice – At dawn deep booming notes, first 3 rising last 2 an even pitch – often followed by sharp ‘BMM’

• Habitat/behaviour – forest floor.

Razor-billed curassowMitu tuberosum

Which sampling method?• IUCN category – LC• This species has an extremely large range, and

hence does not approach the thresholds for Vulnerable under the range size criterion .The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion. The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion. For these reasons the species is evaluated as Least Concern.

• Voice – Song bouts include variable high metallic sounds and deep buzzes, but a characteristic sound is a series of quiet, descending notes followed by a loud, descending thin whistle that ends with a loud buzz “tsew tsew-tchew SEEEEEEEE’ BZZANG”

• Habitat/behaviour –

Golden-headed manakinPipra erythrocephala

Which sampling method?

IUCN category – LCThis species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion. Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion. The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion. For these reasons the species is evaluated as Least Concern.Voice – Habitat/behaviour –

Black-collared hawkBusarellus nigricollis

Which sampling method?• IUCN category – NT• This species is classified as Near Threatened

because it is suspected to be declining moderately rapidly owing to hunting and habitat loss.

• • Voice – Call a long, descending, mewing

whistle, lower pitched than other large raptors “HEEleww”

• • Habitat/behaviour – Rare in humid forest of

eastern lowlands. Rarely soars. Hunts within vegetation, waits from perch in canopy or subcanopy, then weaves through foliage to capture large mammal prey or to move to new perch. Large and bulky eagle.

Harpy EagleHarpia harpyja

Which sampling method?IUCN category – EN A2cd + 4cdThis species qualifies as Endangered because it has been affected by very rapid rates of population decline caused by trapping for the cagebird trade, plus habitat loss. Future population declines are projected to be slower, but still a serious cause for concern. Voice – Flight calls include a low rolling “jurt” as well as a series of scratchy calls; also conversational vocalizations including calls given between members of a pair. Habitat/behaviour – Usually seen in pairs and small flocks. Feeds on flowers and seeds of large trees. Orange under wing coverts are prominent in flight.

Grey Cheeked ParakeetBrotogeris pyrrhoptera

2. Ecological census techniques2. Ecological census techniques 2. Ecological census techniques2. Ecological census techniques

Part 2: Bird sampling challenge

Before conducting a bird survey you need to clarify why you are doing the study,

e.g.

• To investigate the total number of bird species in a given area and the relative abundance of each

• To monitor changes in bird abundance and diversity over time

• To use birds as indicators of ecosystem changes

FOR THIS EXERCISE – you are going to choose the best method to find out the abundancy and

distribution of a specific species.

Which SURVEY method would you use?


• Biodiversity management needs an accurate, precise and unbiased assessment of the numbers of birds of a particular species.

• To get these figures the correct and most suitable sampling method/technique needs to be chosen.

• In this challenge you are going to choose the most suitable sampling method for 6 different birds that you find locally.

• You are given the choice of using ONE of three possible methods for each bird (you should see some of these techniques in action during your week here).


Instructions:1.In a few moments get into groups of 3 people.2.Read the THREE sheets on the different techniques you might use to find out how many birds of each species there are – take ONE card each.3.Then explain your technique to the other members of your group.4.Now take TWO bird info. cards each – read them very carefully and decide on which technique would suit that bird the best – there may not be a correct answer and it could be open to discussion!5.Fill in the answer sheet with the rest of your group.6.There is also a summary table comparing the techniques which you will find useful.

At the end – discuss your choices

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WALLACE RESOURCE LIBRARY Lecture 04 – Terrestrial Survey Techniques in Guyana