To answer your questions,
1. Yes snakes, spiders. Yunta is “inside” the dog fence, so dingoes sightings are fairly unusual, though not unheard of. Nothing that would eat a child without leaving a trace - closest you’d get is feral pigs (they’ll eat entire lambs, young goats etc) which are also unusual for the area but leave a lot of damage to the landscape so if they’ve been spending time anywhere on the station it’d be pretty evident.
The maps I’ve attached below are from the official reporting mechanism landholders must use to report feral animals, so you can see in the last 12 months there have been sightings near-ish to Yunta, looks like within a couple hundred kms, but not a huge amount.
Dingoes in pastoral areas are generally pretty wary of humans in my experience - but I’m not a lone 4 year old either.
No crocs etc this far south, looks like they’ve searched the dams very thoroughly regardless, and I’d expect tracks or signs of struggle around the dam if he did enter one and get stuck or slip under the water.
Kangaroos are surprisingly vicious if caught at the wrong moment, their claws will tear through skin, ligaments and veins like a knife, but again they don’t really attack unless disturbed or under perceived threat, so I wouldn’t say it’s likely option and would be quite surprised. Kangaroos are herbivores so they definitely don’t attack for a feed.
2. Mild spring temperatures at the moment, so 6°-12° degrees over night and up to 30° during the day, mostly around the mid 20°s though. Very blustery & windy during September, so the wind can make things quite chilly if you’re not out in the sun. Still quite a risk of dehydration regardless.
3. Yep, that’s correct.
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