Out for an adventurous drive last weekend, stopped by the side of the road for a break, as you do, and hear two birds calling back & forth across the road to each other. It took us a while to identify the calls, but they were identical to a Mistletoe bird - not just a little bit similar, identical. Even compared the call on the spot courtesy of a recording.
The problem though is, we don't have Mistletoe birds in Tasmania. 
We don't even have Mistletoe, apparently, and unless I've misunderstood, Mistletoe is the Mistletoe birds' main (almost only?) diet isn't it? Even if the birds flew across the Strait with seeds inside them, which I understand they are thought to be able to do, they would have to reach here within 30 minutes or so of consuming their breakfast in order to drop the seeds for them to have a chance of germinating. Even if they clung on to the side of Qantas flight whatever, not a chance!
So, does anyone know if there is another bird which has a call the same as a Mistletoe bird? Didn't spot the "mystery" bird, but I will be going back to that particular place as soon as I am able hoping for at least a chance to record the call.
I think you probably heard a striated pardalot. Their call carries much more than a mistletoebird, whose call isn't very distinctive. Mistletoebirds are pretty active and don't stay in one place, while the pardalotes will stay and call to each other for a long time.
Yeah, definitely not a Mistletoebird.
More info on specifically where you were and what the habitat is would help a lot. I grew up in Qld but live in Tas now. Been a while since I heard M'birds - I've only heard their non-descript contact call, but I gather from my bird app they have a song also. Their song on my app at times sounds vaguely similar to a Pink Robin. Their other calls could be similar to a Thornbill / Silvereye / Pardalote......
Hope that helps!
Cheers, Scott.
Thanks Greg & Scott. Well, mystery still remains, still no sighting of the "mystery" bird after another trip past the same spot, but same calls heard again. I need to be better organised when we go down there next week to record it, if I am able to hear it again that is.
Sorry Scott, I forgot to mention the location. Roughly 20km outside of the Cradle Mt National Park, Murchison Hwy side. I'll check Google maps for a less vague location when I get the chance.
Definitely could be any of above you gentlemen have listed and I think you may be spot-on about the Striated Pardalote particularly. Although, between calls I've heard from those birds, and every recording I can find, none match exactly. Still, I'm the first to admit I doubt I've heard all their/the calls known to man (or woman) either, that's for sure
.
Pending a more organised trip back by myself to try and get a recording or face to put to the sound, if anyone has the Michael Morcombe e-guide to Australian Birds installed on their smartphone, the call was exactly the same as Mistletoe Bird, Call #2 "AM - song 2".
West Coast Tasmania
I have the app... Brainwave!!! Strong-billed Honeyeater - check it out, I think I'm right!! Maybe.....
Cheers, Scott :)
By George (or by Scott
) I think you may just have something there! I've never heard individual calls, certainly not as loudly as these two were going at it anyway, only usually groups. Perhaps it's something they do heading into spring, being the season for romance and all that stuff? Think you may have won the sheep station Scott 
- will get a recording if I can anyway, just for curiosity etc too. At least I know now what I'm probably looking for. Thanks for that!! 
West Coast Tasmania