Interpreting activity counts in GPS collars
The Lotek 3300SL GPS collars have a built-in activity counter.
The activity counter counts the number times that the collars
tip in the x-axis direction and the y-axis direction every
5 minutes. The count is written to memory for each 5-minute
period, 24 hours a day, 7 days a week. An example 24-hour activity
count from a collar worn by Canada lynx L06 suggests that there
are clear patterns of activity and inactivity.
Even though there are what appear to be clear periods of activity and inactivity,
the activity counts should be calibrated with activity counts recorded while
behaviors were being observed. This type of calibration is possible to do with
animals such as moose (Moen et al. 1996), but is difficult to do for small,
rare carnivores such as the Canada lynx that are free-ranging.
Calibration of activity counts is being done with collars worn by captive lynx at the Wildlife Science Center located in Forest Lake, Minnesota. These animals are being monitored 24-hours a day with infrared surveillance cameras similar to those used in store security systems. Using these videotapes, and the activity counts from the GPS collars, we will be able to calibrate some activities with recorded activity counts.
A typical frame grab from the videotape looks like this:
When calibration of activity counts on collars worn by captive lynx will help
us interpret the meaning of activity counts recorded on collars worn by free-ranging
Canada lynx. A press release (with video) on the calibration
experiments was released by NRRI on September 15, 2004.