A while ago - maybe 2004 - I did an article for S China Morning Post, about problems facing Deep Bay, especially the rising mudflats. (Which it seemed AFCD couldn't or wouldn't see; I remain sceptical of their measurements using GPS - not at all sure re accuracy; random errors might explain why they took various random looking readings]).
Article's at:
Deep Bay wetland threatened
This followed the evident startling rise in level of the mud, most obviously in front of boardwalk hides (most obvious as so many observations from there; back in the day, a 1.8m tide brought tideline to the original boardwalk hide! This was constant for a few years, then a relatively sudden change; I believe as tidal regime in Deep Bay shifted thanks to projects including straightening the Shenzhen River)
So, mangroves not really the main issue, perhaps. I believe they are following the movement of the zone that suits them (tidal, but not covered for too long during day).
Was told of algae growing on top of the mud that likewise can't be covered for too long in a day: this used to be behind original boardwalk hide, and has surged out - beyond even the new hide.
Even outside the new hide, can nowadays seem more like you have patch of brackish, almost freshwater marsh in front: algae, grass, yellow wagtails and little ringed plovers and so forth happily feeding.
Again back in the day: I remember being in original hide, having avocets pushed up by tide, feeding right in front; so too shoveler. Now, barely anything for them to feed on here it seems.
SO while I believe mangroves should be chopped down in various places, inc Tsim Bei Tsui; and kept clear in front of boardwalk hides (where the expanse of mud is highly artificial), key issue is surely the rising mudflats.
Plus the fact the flats are rising, leading to steep channels; not just a migration of mudflats out into the Deep Bay (this info from a Dutch mudflat expert who was at Mai Po as I did the article).
So yes, the intertidal birds are being squeezed.
Mind you, thanks to projects like Saemangeum in S Korea, there aren't so many birds to pack into the bay as a few years back! [albeit avocets are doing well]
