Wildlife - Survey Methods

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What are surveys?

  • A method of gathering information from a sample of people/animals, traditionally with the intention of generalising the results to a larger population
  • It is important for scientists to record the changing numbers of animals as well as where they seem to be living
  • Find out data
    • Change to a population because of global warming
  • Advantages
    • Can track a population trend
  • Disadvantages
    • Can be over simplified
    • Can be opinion based
    • Some people may not be truthful
    • Limited options for
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Why do we carry out surveys on animal populations?

  • Species management
  • Monitoring management activities
  • To be able to understand long term trends
  • Is the effort working?
  • Will help you determine if your management is working
  • May help you identify population declines/habitat problems
  • Provides a picture of the health and diversity of the area
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When carrying out a survey you need to think…

  • What is my aim? What do I want to achieve? What is my target species?
    • Could be varied or generalised
  • Mammals? Insects? Plants? Birds? Amphibians? Reptiles?
  • Carnivores? Prey species? Resident birds?
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Keep In Mind

  • No survey method is 100% accurate 100% of the time
  • It is a good idea to repeat surveys several times and compare the results
  • Surveys must be repeatable for future surveyors to carry out
    • Detailed methodology
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Methods of Sampling

  • Some animals can be large – such as various mammals and therefore easy to see and count
  • Many species are small or highly secretive and the surveyor depends on evidence such as tracks and signs such as:
    • Direct Count
    • Line Transects
    • Live Trapping
    • Tracks
    • Droppings
    • Feeding Remains
    • Camera Traps
    • Light Traps
    • Baited Traps
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Survey Types: Direct Count

  • Actually counting the animals one by one
  • Species it can be used for: elephants, deer
  • Advantages: easy and simple
  • Disadvantages: not always accurate (human error)
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Survey Types: Line Transects

  • A tape or string laid along the ground in a straight line as a guide to a sampling method used to measure the distribution of organisms. Sampling is rigorously confined to organisms that are touching the line.
  • Used for: plant species, corals, species that don’t move that much
  • Advantages: good for species that don’t move, simple
  • Disadvantages: can miss a lot of species
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Survey Types: Live Trapping

  • Traps where the animal is kept alive
  • Used for: Can be used for small mammals
  • Advantages:
    • Can leave it overnight
    • Helps find species that are hard to find
    • Animal is uninjured and alive
  • Disadvantages
    • Stress for animal
    • Can catch other species that you’re not looking for
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Survey Types: Tracks

  • Signs left behind the animal that shows it has been to that location e.g., footprints
  • Used for: hoofstock, big cats, otters
  • Advantages: can help you find an animal or somewhere animals gather, can help you find an injured animal
  • Disadvantages: hard to identify exact species between similar animals
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Survey Types: Droppings

  • Used for: deer, otters, elephants
  • Advantages: shows the biology of the animal (stomach type)
  • Disadvantages: sometimes hard to identify
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Survey Types: Feeding Remains

  • The remains left over from an animal’s meal
  • Used for: badgers, foxes, larger mammals, frugivores
  • Advantages
    • Shows the kind of diet the animal has
    • Shows the animals ability to hunt and forage for food
    • Shows the animal is healthy enough to eat/hunt
  • Disadvantages
    • Difficult to tell what animal it is from
    • Not guaranteed it is from the animal you are looking for
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Survey Types: Camera Traps

  • Video footage or photographs of animals that pass by a lens that is sensitive to movement. A special camera in a protective casing set in a spot (a visible walkway with deer tracks on). When an animal walks past the camera a sensor should detect the movement and begin to record.  
  • Used for: Works for most larger species, including deer, big cats, wolves, pigs, can check animals when you are not around, check inside animals nests
  • Advantages: can be placed in remote areas where access is difficult, human presence will not alter animal behaviour, can have night vision, can look back over footage
  • Disadvantages: if the animal does not set off the camera then it won’t have its picture taken, can be broken by animals, time consuming to check footage
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Survey Types: Light Traps

  • Used for: moths, animals that are sensitive to light (phototaxis species), species with transverse orientation
  • Advantages:
    • Draws in animals from a wide radius
  • Disadvantages
    • Needs power
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Survey Types: Baited Traps

  • Used for: rats and mice
  • Advantages
    • Animals are voluntarily coming into the trap
  • Disadvantages
    • Can cause stress when trapped
    • Can cause confusion
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