And yes, I took that photo with my 100mm macro lens, as I could easily get close enough. Normally, when we enter the aviary, the finches retreat to the far end (it's a large aviary). However, the young finches aren't as wary of people, and I could get close enough to touch this youngster.
The four young Gouldians tend to stay together, often huddling on a branch together.
Note the shiny blue bits on each side of the beak. Apparently it helps the parents when feeding their young ones in the dark. Before these young finches left the nest, when looking into the (dark) nest, these shiny bits certainly showed up in the dark.
The feather colours of the young Gouldians are quite drab, with the back and tail feathers being an olive-green, and the rest of the feathers a dull gray. However, as they grow older, they will put on more colour, eventually looking as bright as one of our adult male Gouldian finches shown below. The female Gouldian finches are a similar colour, but not quite as bright as the males.
This is the first time we have had baby Gouldian finches. After breeding Zebra finches for a number of years, we decided to try some slightly more exotic finches, and both our Gouldian pairs have settled down in a nest. The young Gouldian finches pictured above left the nest about a week ago, and the other nest contains another four Gouldians, who will probably be ready to leave their nest in a couple of weeks.
To the person who ended up on this page when googling for the phrase "will gouldian finches stay with zebra finches", I can confirm that Gouldian finches will happily co-exist with Zebra finches.
However, we found that with a lot of Zebra finches, and only a few Gouldians in the aviary, the Zebras tended to bully the Gouldians, and would prevent them from using the nesting boxes. Once we got rid of most of the Zebras (we only have one pair), the Gouldians could use the nesting boxes without being bullied by the Zebra finches.