I had a good discussion with Parks rangers a while back on this.
The biggest problem with vermin is that people do things like throw foodscraps into the composting toilet, which attracts them.
Also not cleaning up around themselves in the huts is a big attracter.
And we all know they like huts - Echo Point has a reputation, and indeed I believe some subtle baiting has been done there. Pine Valley hut is active, as is Narcissus hut (we had to use the top bunks and be creative with our storage), and High Camp hut on Mt Eliza has a little antichinus or some such living there -

The mice we saw at Narcissus looked more like the typical house mouse, but it could have been native, I'm no expert.
I wonder about hygiene issues with these rodents feeding on foodscraps thrown down composting toilets and then living in / wandering through huts.
I noticed on the first 3 days of the Overland track, someone had thrown down a couple of whole carrots, a few celery sticks, then I think it was apples on thge 3rd day. I reckon I know who but won't name them, suffice to say it was a school group.
I also noticed at Windy Ridge, some idiot had thrown food in the toilet there, plastic bag and all.
And we wonder why there are resident vermons in the huts?
So long as you store your gear wisely you shouldn't have too much difficulty with rodents - hang your packs so they can't climb along rafters and get to it - bring some builders line or some such strong nylon string so they can't climb it. Worked for us!
On the OT, I haven't heard of rats but certainly mice / mice sized critters.
Here's the Parks sites on rodents...
http://www.parks.tas.gov.au/wildlife/ma ... dents.htmlFact sheet - click to open, or right-click - save as (PDF file) -
http://www.parks.tas.gov.au/factsheets/ ... odents.pdf(comes from
http://www.parks.tas.gov.au/factsheets/ - worth a look)
For the latest information on how to manage yourself against the rodents of the park, my advice would be to call the ranger office in either Cradle or Lake St Clair and have a chat with them. If you get someone that "isn't sure" (more likely in Cradle), ask for a senior ranger or someone that might know how bad the problem currently is - they generally get a good bit of feedback. As most people walk Cradle to L.St Clair, it might be better calling St Clair. I've always found parks staff great to talk to and up with the latest. Though I have heard someone comment negatively on an experience at Cradle with what seemed more like a temp worker - not first hand so can't verify. I don't generally like to bag out Parks.
Now if you are camping in your tent, introduce the possum problem. People unwisely feed them and they get used to humans - so much so that you can find them climbing under your tent vestuble if you are sitting two metres away and have your back turned.
If you are sleeping and have things stored in your vestuble, sit your billy on top so if you wake up to the sound of your billy tumbling about, bash and shake the tent and make a bit of noise. Has worked for me in the past.
Off topic - funny thing, I was camped at Lake Cygnus on Western Arthurs and woke up in the night to what sounded like a possum poking around the vestuble. Shook the tent & made a noise, all well, back to sleep.
Next morning er woke up to a couple of inches of snow and the "possum" I heard would have been snow sliding off the tent in the night.
