A cuckoo in the nest? (1 Viewer)

I am assuming this is a cuckoo chick in a nest of black redstarts. The nest has been home to dozens of b.r.'s over the years but we found this larger chick on the floor under the nest - too young to fly yet. So I popped him back in the nest where he/she smothered the 3 br chicks in there. The mother br is now trying to feed the lot.
I thought cuckoos always ousted the original eggs before laying their own?
Or will the cuckoo chick chuck the br's out at some point?
The br chicks are tiny - too small to have ousted the cuckoo chick, so I think it much have just fallen out.
Also, how come the cuckoo chick is so much more advanced? Would it have hatched sooner than the br's?
Sorry for quality of second photo - obviously can't get too close to an adult bird. There are 3 BR chicks, not 2. Usually there are 4, so maybe 1 got ousted.
Any comments?

Can't be a Cuckoo?

It would have hatched and ejected either eggs or siblings leaving it alone in the nest?


Andy

Not a Cuckoo; they have a smaller bill. Looks more like a sparrow or finch type bird; though also worryingly like a Brown-headed Cowbird chick (could be a serious invasive species if it did ever colonise Europe!). Keep adding more pics over the next few days.

Where were the pics taken? If Britain, I'd hope you've got a schedule 1 license

2 more pics

These babies are in SW France.
Funnily enough, there has been a sparrow family here this year - the first I have seen in our garden for years, but we do get a few whinchats and I wonder if this might be one of those - see the white streak down its chest.

It has now left the nest - much to the relief of the natives I suspect. Not sure if mother black redstart is still feeding it.

2 more pics . . . .

That beak says sparrow/finch/bunting, definitely not a Whinchat (which would have a similar bill to the Black Redstarts - they are in the same family). Some brown streaky feathers seem to be visible in the latter photos, which makes sparrow seem likely.

If you first found it on the ground under the Redstart nest, it probably came from a different nest, rather than being a brood parasite...

stevethehydra said:

. . .If you first found it on the ground under the Redstart nest, it probably came from a different nest, rather than being a brood parasite...

Click to expand...

Indeed.