Yes, there are a number of adult & juvenile White-cheeked Starlings around at Mai Po (as well as other starlings) and it seems clear that they breed somewhere nearby.
This particular individual, however, is I think a little problematic - for three reasons:
1) It is very approachable. I photographed it on July 3. Vivian - according to the website - photographed it on 6 July.
2) The bill - at least to my eye - is deformed/damaged at the tip. This is a feature of Vivian's photos and the photos I took on July 3. It is this that makes me sure that the bird I saw & photographed is the same as the one Vivian photographed.
3)The tail is clearly abraded, although I accept the point that this could be a result of being crammed into the nest with siblings etc.
I didn't conclude that this was an ex-captive bird - I just wondered if it was one because of the features I've mentioned above, and I'm grateful for the response.
It's of no great importance, of course, since White-cheeked Starling is a fairly common bird in HK. But if a rare bird turned up in HK and showed the above features, then - more likely than not - it would not be accepted as being a genuine vagrant. Hawfinch springs to mind as an obvious example.
David