Recently I did a search on various wildlife tracking techniques. 
At the moment a wide, and rapidly expanding, range of tracking devices are available. From state-of-the-art VHF GPS SATELLITE collars on elephants to little VHF TRANSMITTER BACKPACKS on bats and birds and everything in between: VHF, UHF, GPS store on board, remotely downloadable options, ARGOS, GPS ARGOS, NORTHSTAR, automatic drop-off, remotely controlled drop-off, collars working with the mobile network and many more options. 
Because the performance of tracking devices on different species and in differen regions (climate, satellite coverage) vary a lot, and many companies don't have a wide experience with their type of collar on the animal you want to track in the region on earth you want to track it, it's difficult to find out which collar suits your research best.

So I started looking for news groups about collar but I found none. 
I now started a group: http://uk.groups.yahoo.com/group/WildlifeTracking

This group is intended to share experiences on the wide range of available tracking devices. And to provide answers/advice on the choice of collars.

Regards,

Egil