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Chapter 2: Micro-level survey design

Part 1. Foundations of SCR survey design

Here we cover one of the most common and important questions facing a researcher about to embark on a camera trap survey: where do I put the cameras? We describe the overall goals of many SCR surveys, which is to estimate animal density or abundance precisely, and without bias. Then we look at what these goals mean for survey design.

Part 2. Examples of good and bad survey designs

In this video we reinforce the principles introduced in the last video by showing a few examples of designs that are bad, sometimes obviously so and sometimes less obviously. By looking at specific examples of how things can go wrong, we build up to an understanding of what we need to do to get a design "right". 

Part 3. Software for designing SCR surveys

Here, we walk through the use of the "secrdesign app", a Shiny application developed by Murray Efford, developer of the secr and secrdesign packages. The app provides an interface to the secrdesign package without needing any programming, and lets you assess the expected quality of any potential camera trap design before you head out into the field.

Part 4. New developments in SCR survey design

Here, we talk about some new-ish ideas in SCR survey design - that camera trap locations can be chosen in a kind of optimal way. We look at two optimization criteria that seem promising:

  • Camera trap placements that maximize the probability of detecting animals twice - this emphasises recaptures but the focus on "twice" means that the emphasis is only moderate (and potentially just right).

  • Camera trap placements that balance recaptures and the number of unique animals seen. This criterion has been shown to be approximately related to the precision of animal density estimates, so there's a statistical justification for it, if only approximately... 

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