How do I design a Visual Encounter Survey?

How do I design a Visual Encounter Survey?

A visual encounter survey is simply a systematic survey of wildlife, by following a predefined transect and relying on visual contact. Often, visual encounter surveys involve audio encounters, particularly with vocalizing birds or amphibians. Examples of Visual Encounter Surveys:

- Following a predefined trail and noting any reptiles or amphibians you encounter.
- Creating a straight line through a field and marking any plants that fall within 3 meters of that line. 
- Following a predefined path, and spotting birds using binoculars for 5 minutes every 200 meters. 

Some general best practices for VES:
  1. Avoid back tracking on your survey or you may end up double counting.
    1. Design your survey to be a loop 
  2. Depending on your study, consider randomizing:
    1. The direction you start down a loop trail
    2. The times you start
    3. Which transects you sample
  3. Plan with your target species and study goals in mind
    1. General surveys should randomize more and be more general
    2. Surveys for specific taxa should be planned with their activity levels in mind
    3. Be aware of these biases in your results!
  4. Not everyone is as skilled of a searcher. Ensure your team has a diversity of talents.
  5. Record the number of people you survey with and start+end times for your surveys.  You'll use this to calculate people hours you surveyed.
  6. Be intentional about what data you collect. It may not be feasible to stop for measurements every time you spot a lizard. Also, you have to carry everything.
    1. Some organisms can be collected, measured, and released a later time.
    2. General data that dont require an organism are great (temperature, humidity, weather, canopy coverage, habitat type etc.)
    3. Some data can be collected from date, time, or GPS coordinates after the survey period
      1. Distance from water
      2. Lunar cycle
      3. Habitat type (if predefined)

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