Courtship feeding ????: Scaly thrush Zoothera dauma, Eurasian jay, Garrulus glandarious

Courtship feeding is one of the well-known behaviour of birds such as terns raptors,

and some passerine birds.

At least for me, This was unique behaviour that I've observed during my birding times since 2006.

It happened on 25, Aril, 2009 at Seoul national university campus.  around 09:00

At first, I was watching migrating thrushes foraging on grassy part of the forest patch, there were several Scaly thrush, Pale thrush, and Grey-backed thrush.

It was a thrush feast, abundant drop of thrushes that day was memorable.

and then, I've noticed a bird flew in to another scaly thrush.

It just happened.

the bird arrived, and almost immediately passed it's prize,

a moth larvae which is commonly seen on grasses.

and the original bird swallowed.

there were no after coitus or other intriguing behaviour right after few minutes, they just moved closely, the later arrived bird followed former bird gently. until flushed by an motorcycle -pizza delivery man.

although I could'nt observe any other signs, these birds were definitely not parent-siblings of that year, too early for breeding season and fledging, and the fed bird didn't showed up any begging behaviors commonly seen on feeding parent and their chicks.

I suggest these behaviours are some sort of courtship feeding of early-arrived local breeding pair, or courtship behaviour to probable mate on their way migration.

I could also notice some structural difference between those two birds, assuming the're different sexes,

with smaller size and shorter, slender bills of front(Later arrived bird).

I've seen another courtship behaviour in passerines, Eurasian jay. at April, 2007. In this case, I cannot assure it is an courtship, more than a scaly thrush, because jays breed much earlier than thrushes, there are much more possiblities that this fed bird is sibling of feeding bird. and also, I observed some begging behaviors calling, and wing flutterings too.

I'm curious that does adult-birds who are fed by courtship feeding shows any begging behaviours, and if they do, are those behaviours differ from their juvenile experience?

and also, how does birds of different species show similar form of begging behaviors?