Dear CarolB,
This is a great finding!!
I'm not sure about the ID of this bird. I think it is making nest there. But please do not disclose the location to anyone since breeding birds are very sensitive to human disturbance and the bird may abandon the nest or even the eggs/chicks in the worst case.
Please also try not to visit the site frequently to minimise disturbance.
Thank you very much!!
May experts please help ID this bird?
HKBWS