Wildlife sampling methods Lecture 7 part 2 Flashcards
What can Survey results do?
Identify priority areas for species protection
Develop conservation management strategies
Help mitigate threats
What is Non-invasive monitoring ideal for?
Ideal for estimating abundance
Trends
What does invasive monitoring involve?
Trapping
Collaring
Disease transmission from humans
List the Non-invasive survey methods
Interviews
Index counts
Direct and indirect distance sampling methods
Capture-recapture methods (Inv or uninv)
Line/point and Strip/quadrat transects
List the aspects of Capture - recapture with camera traps
Effective tool for monitoring terrestrial mammals - precise density estimates
Enable population estimates- Social, demographic structures, movement patterns
Presence/absence of arboreal spp.- Monitoring tool
Effective at small spatial scales - 200km
Larger areas - transects or genetic censuses
What are the different scales of monitoring or assessing populations?
Site level
Protected area
Regional
National
Continental
Different methods are appropriate at different scales
What will you need to gather information on?
Survey species
Area to be covered - Behavioural, ecological characteristics of the target species. Ranging patterns, habitat requirement
Map of the survey area- vegetation, topographical hydrological
Previous data
Answer: Why, what, how, where, when, how often?
Why is it important to survey?
Reason is defined by survey objectives:
To estimate -
Distribution
Abundance
Population trend
Population structure
What questions can the information of spatial distribution of a species answer?
Can help answer questions on whether
A species. Is restricted to a particular area or habitat type
What is species occurrence influenced by?
Species Occurence is influenced by environmental, anthropogenic or temporal factors. For example: Seasonal variation in food abundances.
In relation to abundance, what different measures can be estimated?
Relative abundance
Index, encounters rate of signs, per unit distance - caution needed when interpreting these results between sites or habitats
Absolute abundance: Total number of individuals in the survey area
Density- Absolute abundance divided by the size of the survey area (Number of individuals per km2).
What is population trend for?
For informing and assessing effectiveness of conservation management decisions
Aimt to estimate trend over several years
Need to be repeated over a no. of years.
Explain population structure
Requires obtaining info on the age and sex classes of the individuals sampled
Maybe easy when surveying directly
More challenging when surveying for indirect signs - difficult to assign age and sex classes
Provides useful insights into reproductive health of a popln, immigration and emigration patterns, population trends and population viability
What does Ecological censuses investigate?
Site importance
Population size of a species
Habitat requirements of a sp.
Reason for species’ decline
Habitat management
Population dynamics
Give examples of Census
Ecological status of 6 parks in sandwell
BSc project - GCN poplns in pools in Fibbersley LNR
EIA for a development
BTO thrush survey
RSPB garden bird survey
Describe the importance of a site for a range of species
Provide a spp. List with a rough estimate of abundance
Use a wide range of different techniques
Sample in as many habitats as possible
Over a wide period of time
Over different weather conditions
Document the area searched
How do you monitor population changes?
Monitor the fate of a species of conservation interest
Not necessary to have an absolute population estimate
Relative measure of abundance may be sufficient
Ensure exactly the same techniques are used each time
Must ensure that comparisons are valid
May also be necessary to measure env variables at the same time.
How do you determine population dynamics?
Measure life history parameters
Estimate the population size
Consider a range of questions:
Why does the population fluctuate from year to year
What determines the level of abundance?
How strong is density dependence and at what stage does it operate
What are the consequences of competitors, herbivores or predators on the population?
How do you determine habitat requirements?
Not necessary to have absolute population estimates
Can’t just visit all the best sites
Need to be able to compare sites where species. Are absent
Could use a random collection of points
May need to asses prey abundances, predator abundance, nesting sites, habitat structure, env. Variables
Could be presence/ absence or relative density
How do you determine why species have declined?
Could use the previously mentioned methodology and try to determine whether factors have changed or…
Compare the sites in which the species still occurs with sites where it has disappeared
Estimate life history parameters
Asses the limiting factors - determine if they have changed
What is involved with monitoring habitat management?
Need to learn from the results of the management that has carried out
Need to be sure that the right conclusions are drawn
Management experiments need to be controlled, randomised and replicated
Replication is required
Why must you sample?
Not possible to count all individuals within a given population (Population = total number of a particular species in definite area)
Aim to select a small representation of the total population
Must divide the area into sampling units of equal size
Sampling units must be distinct, must not overlap, must be of the same size and each unit must be chosen at random from the whole population
A group of units is selected and will be representative of the whole population
What is sampling and how does it work?
Collecting data from a representative sample of the population (A collection of all the items about which we want to know some characteristics).
Often may require a sample from a TARGET population
The sample must be representative of the WHOLE population and not be biased in any way
The sample must be as representative as possible
Must collect as many samples as is feasible in the time available
What does sampling cont involve?
Samples must be independent of one another
May be constrained by TIME and COST
The point of sampling is to deduce information about the entire population
Need to make inferences
The sample must be free from bias
The optimum sample is one which maximises precision per unit cost
How do you decide on a sampling strategy?
Selecting a sample involves the formulation of rules and procedures, by which members of the population are included in the sample
The chosen sample is then measured using defined procedures to obtain the relevant data
Good sampling design should provide valid estimates of the population of data you are investigating
2 primary types: Random and purpose (information- rich)
How does Random sampling work?
Overcomes biases
Divide the area into blocks
Stratified random sampling
List the types of distribution of individuals
Homogeneous (Uniform) - evenly distributed
Patchy- showing a clustered distribution
Gradient - a distribution that varies smoothly over the sampling area
Stratified - showing a distribution which discret levels or strata
List the different distribution types
Random distribution
Aggregations Regular distribution
Patch distribution
Distribution in the form of a gradient, with
Showing a steeper gradient than ^
What is the sampling protocol?
Should decide on this before an investigation proceeds
The main aspects to be determined are:
The position of the sample
The size and shape of the sample area
The number of sampling units in each sample
Need to know the likely distribution of the units under investigation
Truly representative samples should normally?
Taken at random, or in a way that ensures that every member of the population has an equal chance of being selected
Large enough to provide sufficient precision in estimating population parameters
Unbiased by the sampling procedure or equipment
Should use the resources efficiently
Explain Bias
Intentional bias
Conduct during optimal conditions of the sampling method and for the species studied
Time of day, year, weather conditions should be considered
Consistent bias - objective of relative abundance surveys
Unbiased/ precise estimates - objective of absolute abundance surveys
Give examples of Bias
- Effort bias
- Habitat bias
- Species/sex/age/class bias
- Density bias
- Activity bias
- Seasonal bias
- Time of day bias
- Tidal rhythm bias
- Weather bias
How does identifying individuals work?
May be essential in some studies
BUT may be impossible within a group
Need to be distinguish reliably between one another
Resulting data is then more informative- can distinguish differences in known individuals
All individuals in a species. Do not behave in the same “species-typical” way.
Marking methods identify by?
- Tagging
- Banding
- Transponders
- Micro chipping
- Notching
- Tattooing
- Dye marking
- Clipping
- Branding
What can marking alter?
marking it may alter its behaviour or that of the others with which it interacts
What is the problem with identification in the field?
Marking presents problems
May need traps, nets, drugs
Some forms of marking don’t last long
Traps need to be monitored
What do you need to do to identify in the field?
Need to minimise stress - Reasons are scientific and ethical
Some species. Individuals have distinct markings - stripes, noses, ears, whisker spots, fins, tails, bills, scale patterns
Some acquire distinctive marks
Can be difficult
Requires verifiable demonstration of you ability to distinguish between the individuals
Whats involved with tracking in the field?
Various techniques enable individuals to be tracked over long distances
Radio transmitters
Low level radiation
Collars can be fitted with GPS and data loggers
Explain individual distinctiveness
Animals have distinct personalities
These can be rated reliably - capture overall patterns
For example bold or timid, aggressive or submissive
List observations what than be differences in individuals behaviours
Statistical techniques are used primarily for drawing inferences about populations
Aim to remove the troublesome effects of differences in behaviour
Emphasise what members of the population have in common
Some differences in individuals are of biological significance
Can’t generalise to all members of a gp even on age or sex
2 or more reproductive tactics may be present within populations
Animals possess developmental plasticity to respond to environmental conditions in early life
Studies involving measurements of behaviour should take variations into account. For example categorise or ID them
List the rules and methods of defining a group
Rules are usually implicit but should be made as explicit as possible
Assess how animals are distributed in spaces
Observe relative distances between individuals
Distance used depends on species. Sensory capabilities and their environment
Distinguish between groups and parties
The criterion distance could be the distance to the nearest neighbour
May be distributed bimodally
Definition of together will depend on the study:
Problems of definition vary between species
Collective pattern may be the most appropriate unit of measurement
