Good day,
I have a specific remote surveillance application that is proving to be much more of a challenge than I thought.
I need to detect where (GPS fix) African wild dogs (25 kg large canids, wide ranging) deposit their scent-marks.
When a pack reaches a scent-marking site they slow down and mill about, with many changes of direction and body orientation (wrt the cardinal points) in a limited (10 - 20 m radius approx). Once they have done their scent-marking they set off again, usually after only a minute or two. If I can detect the changes in direction and grab a GPS fix, that will allow me to locate the scent-marking site and monitor it with camera traps for subsequent visits and marking.
Added to clarify: I do not need to do this automatically by crunching big data sets, so there is no need to calibrate sensor responses against observed behaviour. I already know, from hundreds and hundreds of camera trap videos from dozens of marking sites how the dogs move around when they get there - all I need to do is to remotely measure and record that movement, and grab a GPS location where it is happening.
Which collar-mounted sensor can detect the compass orientation of an animal's body and/or changes in the orientation or direction of movement. Can an e-compass (e.g.
) do it ? And can the output be used to trigger a GPs fix, to be downloaded or transmitted as for ordinary GPS collars?
If it can, is anyone building these into collars that weigh around 250g?, or is anyone up for a development project?
Thanks, Peter Apps
2 April 2025 3:03pm
Could you not simply detect a certain amount of dogs staying for a certain amount of time in one place as a simplistic check? Either they would be sleeping, in which case it could be a false positive, or they are standing around but not changing direction, rather unlikely I'm thinking.
5 April 2025 5:58am
Hi Peter,
I used Milsar RT14 with modified GPS firmware on Koalas and they record Accelerometer, Gyroscope and Magnetometer in three dimensions with every GPS fix (along with temperature, solar voltage and pressure) and separately they record bursts of Accelerometer and Gyroscope at high frequency or at one Hz for magnetometer, temp and pressure.
I used the bursts at 10 Hz for 5 seconds every 2 minutes which did not use much power (as far as I could tell) but I opted not to use burst data for the Magnetometer or Temp to minimise data download quantities. My Koalas were around 10 kg and the collars which included continuous audio recorders weighed in at 125 grams.
Because koalas live in forest and tend to seek shade during warm weather, the amount of fixes I could collect were limited to about 50 per day or less if the collar turned upside down which was problematic for recharging. There is a bit more info at:
How to Choose a Biologger - Collaring Koalas with Matthew Stanton | WILDLABS
In the penultimate article in my series examining how people find biologging tech for their projects, I spoke with Matthew Stanton about developing custom biologging technology for studying koala behaviour.
I chose to use firmware that prioritised accuracy over saving battery power.
Obviously you would have to make decisions about how you prioritised your power use. Unless you employed a substantial battery on the collar, you probably couldn't afford to leave a magnetometer running full time. In any case it might be worth having a chat to Pawel at Milsar and see if he can make a collar with all the right compromises for your project. One obvious issue with a collar as opposed to a glue on device or a backpack is the orientation of the device is only guaranteed for one axis, but with a non-burrowing canid you might be reasonably sure that it will stay heavy side down most of the time which will make your movement calculations much simpler rather than constantly having to account for device orientation. One disadvantage of the milsar system is that you can't really tie your burst measurements with GPS fixes as they operate on different schedules with the GPS fixes being dependant on how long it takes to update the almanac and then establish a reasonable position.
22 April 2025 2:11pm
Hi Peter, Yes, I have been thinking about this. However, what we can do, is have the accelerometer permanently in sleep mode and to be activated as soon as turning motion greater than say 180 degrees is detected. As soon as that happens it can automatically trigger a GPS fix and this can also be programmed to take one once a minute for the 2 minutes, or something like that.
Basically one could set it up however you wish. This would probably be different for you for the dogs as opposed to me for monkeys or baboons. Another way of doing it could be to trigger a fix as soon as dogs have been moving at greater than walk speed and then suddenly stop running and stay in much the same place. You immediately could take a fix, and if they start turning around, then even better. All this would be recorded.
Also one could also trigger the dead reckoning to come on for a minute or two everytime the trotting dogs come to a stand still. One could also leave all systems on for a few days whenever the dogs are moving. One will then will build up a record of key features prior to and during a scent marking session, and then select from those to find the best triggers for GPS locations. More or less anything will be possible.
Cheers, Phil
Kim Hendrikse