Radio transmitters
Ray Hewson used these to study Mountain Hares. These 'knapsack' transmitters were fitted around the necks of mammals and birds, they fitted snug under the chin and the thin, wire aerial extended 'over the shoulder' and along the back. In birds, they are now sometimes fitted directly to plumage (so that they moult out afetr a time) and in many instances are replaced by satellite transmitters which can be automatically read and viewed, remotely on a computer.
