The habitat of this small woodpecker I seen in elsewhere is something like Tai Po Kau. So, it appears that the woodland at LV does not match with the typical habitat.
Maybe the woodland at LV is a fengshui wood which can support the birds temporarily.
Regarding the bird trade, according to the KFBG report, the live bird trade of prayer birds at Bird Street in 2008/09 is just about 1/5 of 2005, probably due to the bird flu issue. Other birds commonly around were just magpie robin, rubythroate, mesia, peking robin and bulbuls. Birds from africa are also present. It is expected that this bird originated from the Bird Street may be very low. But cannot rule out it is an escaped bird from a keeper around Ho Sheung Heung.