Introduction to Central American forests

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WALLACE RESOURCE LIBRARY Lecture 04 Terrestrial
Survey Techniques in 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.
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WALLACE RESOURCE LIBRARY Lecture 04 Terrestrial
Survey Techniques in Guyana
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Lecture overview

• Sampling methods
• Replication
• Mark Recapture methods
• Distance Sampling (point counts and line
  transects)
• Patch occupancy
• Biodiversity monitoring methods
• Trapping, netting etc
• Research design

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General 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

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Sampling strategies

• 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
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Sampling 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
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Sampling 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

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Sampling strategies

• Line transects
• Transect routes may be used to create
  pseudo-random sampling locations, by following
  a straight line through a given strata.

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Sampling strategies

• 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.

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Mark-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
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Mark-recapture sampling

• Marking
• 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

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Mark-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

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Distance Sampling Line Transects

• 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

Diagram by Sutherland, 2006
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Line 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

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Distance 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)

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Distance 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

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Patch 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)

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Biodiversity 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

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Population 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

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Discussion 1 - Designing research
?

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

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Research question/research objectives

• 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.

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Research 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.

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Methods

• Is the researcher re-inventing the wheel, or
  using more widely recognised methods.
• In some cases, data may be comparable across
  surveys and locations.

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Sample 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.

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Sample 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?

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Spatial 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.

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Control 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.

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Data 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.

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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

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Which sampling method?
Blue and yellow macaw Ara ararauna
IUCN category LC This 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 gRAAAAH!   Habit
at/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
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Which sampling method?
Hoatzin Opisthocomus hoazin
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. 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.
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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 lt20,000 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 (gt30 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 (lt10,000 mature individuals with a
  continuing decline estimated to be gt10 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
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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 curassow Mitu tuberosum
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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 manakin Pipra erythrocephala
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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
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 hawk Busarellus nigricollis
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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 Eagle Harpia harpyja
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Which sampling method?
IUCN category EN A2cd 4cd This 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 Parakeet Brotogeris pyrrhoptera
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2. Ecological census techniques
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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?

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Part 2 Bird sampling challenge

• 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).

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Part 2 Bird sampling challenge

• Instructions
• In a few moments get into groups of 3 people.
• 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.
• Then explain your technique to the other members
  of your group.
• 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!
• Fill in the answer sheet with the rest of your
  group.
• There is also a summary table comparing the
  techniques which you will find useful.

At the end discuss your choices
Click big picture to run the clip