The only problem I can forsee is that the Yowie is already incredibly intelligent, and with it, apparently extremely strong and dextrous, so you'd have to have something like the equivalent of the Sword in the Stone that couldn't be easily carried away. There is some indication that Yowies have used sticks as tools to access termites and ants, so I guess they could figure out other ways to access food.
I was thinking something like a heavy metal box or something, with food items inside, that can only be accessed a certain way, for example, the box could only be opened by using three hands, which would necessitate co-operation with another Yowie perhaps? Or something just plain amusing, that a Yowie might find interesting. For this, I was thinking maybe leave a simple drum or a school recorder or simple flute - it would be interesting if a Yowie would be tempted to investigate what it was, particularly if they figure out blowing into it can make a REALLY loud sound - although if whistling gives them the tom tits, this might not be a good idea! It would be even MORE fascinating if one was to hear a recorder or penny whistle coming from deep in the bush one night!
On a different tack, I know Pixie leaves regular food items out each day for her local Yowie group, but has anything else been left for them to 'play' with?
Ideas:
Soft toys, particularly if quite realistic (i.e. NOT a Barbie doll!) shaped like a person or ape
Hard rubber ball - it's bouncing ability might quickly be realised
Those large sized sticks of coloured chalk - check vicinity for grafitti afterwards!
A large stiff bristled brush - might be a good scratching device! Or we might start seeing well-groomed Yowies!
Simple gifts of polished stones, other natural items etc
I'm not sure if any of these items would have any detrimental effect on a Yowie, as I hope they would have more sense than to just chew everything up, but anything really toxic would obviously be a bad choice - imagine if it's safe for kids, then it should be safe for a Yowie.
I guess this might give them something entertaining to do, if nothing else, but might not really do anything of value for us in our search to understand these hairy fellas a bit better. I just think it might be a cool thing to do that might also give the Yowies an idea we aren't just pests to be got rid of every time they see us about - a kind of non-threatening familiarity programme perhaps? But then, humans have a pretty bad track record of moving in and taking over, so familiarity with anyone might also be a bad idea.
Just my .02 cents, what do you think?
Shazz