I thought I would share this little piece on our use of passive RECCO reflectors on GPS collars for muskoxen in Greenland:

The RECCO technology is based on so-called harmonic radar and was developed for searching for people (equipped with a reflector) in avalanche accidents. But it also has a few other use cases such as helping to locate tranqualizer darts which miss their target animals and it has been used for tracking insects.

We have had colleagues searching for stationary GPS collars have to give up due to deep snow although they had a very good GPS positions (and a VHF signal to assist them).

At our muskox GPS collar deployment last year we therefore attached RECCO reflectors to all collars and we will be looking forward to seeing if it can help when retrieving the collars.

We got a good deal on an old style refurbished RECCO finder unit but our new use case had to be approved by the RECCO company before DANiNJECT could sell it to us

Harmonic radar will not only locate the specially designed reflectors but basically any piece of electronics containing silicium components although detection ranges will vary.