Cam trapping: ten simple steps to process all those amazing photos

Workflow

  1. Read some cam trap papers.
  2. Check camtrapR package and see what it does to decide if it suits your specific needs.
  3. Open folder for each site, each day, each rep.  Do a folder ‘get info’ to count # of total pics.  These are your ‘reps’ within reps, i.e. literally total number of snapshots (or use command line to get dir info for all your photo data).
  4. I would honestly just paste 0’s all the way down because many will be ‘false hits’.
  5. Then, open them all up and scroll through.
  6. Every time a positive hit, overwrite 0 in ‘animal.capture’ vector and in ‘animal’ vector record what it is.
  7. Also, copy all positive hits photos into a separate folder for additional analyses.  Use a folder structure or ID system that keeps track of the place and time that photo was from.  For instance, have a folder entitle positive-hits for each site, day, location, rep or aggregate into a single positive hit folder but use a mechanism to ensure we know where/when photo was taken. Do not cut and paste, copy. This is a backup mechanism for additional analyses and sharing data.
  8. We also want to know when animals are most active, or not; and hence, check timestamps and paste down in that column too. Ideal is actual time but morning, afternoon, night is absolutely adequate and more rapid if we cannot automate the scraping using R-package.
  9. If timestamp is incorrect, do a light-dark assessment to code as night or day – this is a very rapid process.
  10. Record observations if more than one animal or if the same animal was recaptured from previous instance. Record anything of note ecologically to calibrate the quantitatives and link photo-capture processing to data mapping/translation. The goal is to accurately map photos onto numbers that represent the dynamics of the system in study.

Outcomes

The goal is have to have both an evidence folder of positive hits and a dataframe that can then be wrangled to estimate relative efficacy of sampling, frequencies of different animals, spatiotemporal dynamics, and differences between structured treatments in the implementation of trapping.

Meta-data for manual processing spreadsheet workflow

Attribute is the column headers.

attribute description
year we have many years for Carrizo (evil laugh) so good to list here in a vector
region MNP for Mojave, CNM for Carrizo
site if you have more than one site, put name of site
calendar date dd-m-year
microsite larrea, buchhorn, ephedra or open depending on region
day this is census day, 1,2,3, to however many days sampled
rep if more than one rep per day
photo rep just cut and paste to total number of photos each cam took on one day, could be 10 to 10000
animal.capture binary 0 = false hit, 1 = animal present
animal list animal as ‘none’ if false hit, then animal name if one was there
timeblock with animal telemetry work, morning, afternoon, night is usually sufficient 6am to noon, noon to 6pm, them night time
night.day back up if timestamps are incorrect – just do by night and day using light and darkness in photos. very quick
filename.ID.positive.hits
optional depending on your filing system, copy all positive hits to a separate folder. somehow, keep track of positive locations and times for subsequent analyses
observations
record observations of anything ecological that pops such as if there was another animal in the photo OR if it was the same animal repeatedly recaptured