After it warmed up a bit yesterday, I tried out my new digital field protocol on a wildlife tracking transect behind my house. My goal was to record the identity, quantity, and location of large animal tracks in the snow which crossed the path I was walking (my “transect”). I am trying to develop a protocol for purely digital collection of these data.
Three types of data must be collected: date, location, and observation. The date (and time) is easy because most digital data has a time stamp. Collecting location data requires a GPS enabled device. To collect the wildlife observation information in digital form requires manual data entry (keypad or touchscreen) or audio or video collection. I have seen some smart phone apps which could be bent to this purpose, but I don’t have such a phone, so the easiest route for me is audio, although this will require later translation to textual data.
[Update: I abandoned this three-device protocol after a few trials and now use only the GPS to make waypoints for each observation. The new method is described here.]
Linking the GPS data with the audio observations is the hard part. There are mature protocols for attaching GPS coordinates to image files, but not to audio files, although it should be easy to implement this on a smart phone. I used a digital photo as a link between the GPS data and the audio file. A key component of my protocol is a program which attaches GPS coordinates to photo files and can also associate an audio file with each photo. The program can also create a KMZ file or GIS shapefile which includes the georeferenced audio files. The program is RoboGeo which costs $80. This is the program that I use to georeference photos that I have taken while the GPS is recording a tracklog.
If you want to do some extra work, the photo is not required because you can manually associate each audio file with GPS coordinates. This is straightforward because each audio file has a time stamp which can be matched with a point in the GPS tracklog. But the photo allows this to be done automatically by RoboGeo.
My protocol is to walk the tracking transect with camera, digital voice recorder, and a GPS recording a tracklog:
Camera — Any digital camera will work. The photos are superfluous, and are taken only so the audio files can be associated with the GPS tracklog points.
Voice recorder — I use an Olympus VN-6200PC, available for $40. Each time a new recording is made, a separate WMA (Windows Media Audio) file with a timestamp is created. These files can be copied to a computer. Some older Olympus recorders do not preserve the time of the recording in the timestamp of the audio file.
GPS — I use a Garmin GPSMap 76csx. The tracklog is set to record a point every 10-15 seconds. The tracklog should not be manually saved in the GPS unit because this deletes the timestamps.
The clock in the camera and voice recorder must be synchronized with the GPS time.
In the field, when an animal track is encountered, I press the shutter on the camera and then start recording audio. The photos might be very useful for identifying tracks or puzzling out confusing or missing audio recordings, but they are taken primarily to create a jpg file with a timestamp. The audio need only include the species and number of animal discerned from the tracks, but other observations can also be recorded.
This office protocol is still being refined:
•Transfer the photos to a computer. The images I took contained no useful information, so I created very small jpeg versions of each photo. These jpegs must have the EXIF data intact.
•Transfer the audio files to a computer. A USB connection allows the Olympus VN-6200PC to be visible as a storage device, and each recording is a separate WMA file.
•In RoboGeo, open the folder of photographs. Geocode each photo by either linking directly to the GPS (via USB) or loading a gpx file (e.g., made with Garmin MapSource and including the tracklog). Now each photo has lat and long coordinates associated with it. (These coordinates can now be written to the EXIF header of each photo.) Then open the folder of audio files in RoboGeo. These will be automatically associated with the proper photo based on timestamps.
I then exported from RoboGeo to Google Earth. A KMZ file can be created with the tracklog, georeferenced photos, and audio files associated with each photo. During this process, a title can be entered for each photo, so I entered the name of the animal. Now the data displayed in RoboGeo includes species, number, date, and GPS coordinates, and can be copied and pasted into Excel.
To make the photos and audio files available for viewing on the Web in Google Earth, I copied them to this website (they are now stored in a folder on the GoDaddy server). RoboGeo offers the option to include the photos and audio files in the KMZ file, but this did not work. It might be an alternative to putting the files on a server. Including the photos and audio files in the Google Earth KMZ file is not necessary in order to map the tracking results.
Click here to see the result in Google Earth via KML preview (requires free plugin). You can download the KMZ file here. [Update December 29: these KML files now include five tracking surveys and an animated, narrated tour of the transect.] My plan is to walk this transect several times this winter and see what I can learn about patterns of wildlife use. For example, some species might move along particular corridors and avoid other areas. All of the large animals (e.g., deer, coyote, bobcat) travel throughout the town of Salisbury, and this transect divides the populated part of town from the wild part. All the land to the east of the transect is in the Green Mountain National Forest where the highest concentrations of large animals are, and where mountainous topography is the only barrier to travel. To the west, gentler lowlands make travel easy, but roads, houses, and clearings modify wildlife travel routes.
All the tracks encountered during the first survey (December 10) had been made during the previous two days since snow stopped falling. Those last two nights were the coldest yet this year and reached 0°F one night. I expect many more tracks to be visible on other days.