I found these three links on Russ’s blog, and decided they were very relevant to what I’m trying to do with tracking wild rats.
I’ve also been accruing a bunch of Delicious links on RFID. Eric Rosenthal recommends passive tags that have supercapacitors in them for wider range, and then I’d build the transceivers. The research I’ve done has not yielded results yet, there’s just too much out there and I don’t know enough yet to discern the useful from the non-useful. Give me a few weeks.