CliftonQuail
Songster
It stands to reason that there's probably very little, if any, interbreeding between Australian birds and US birds. I suppose it's possible that we (U.S.A) managed to breed them larger over time and it's probably also possible that someone in Australia could institute a breeding program to get a larger bird.That's an interesting idea. I've had Kiki and Nabiki telling me they weren't jumbos for ages, but maybe they are just smaller in Australia. I've never come across a jumbo quail bigger than 300g here.
I found one reference from a US website that indicates jumbos range from 12-14 oz (340 to 396 grams) and standards are 6 - 7 oz, or about half the size of jumbos. I couldn't find any Australian centric sites that gave weights for comparison, but I suspect my hypothesis is correct.