Pinioning may be more obvious with pelicans probably because their primary feathers are really long; the procedure is standard, with the last joint of the wing removed.
I don't know what the park's policy on pinioning is, but i get the impression that it is avoided as much as possible. Some of the greater and lesser flamingos are fully-winged too. For the zoo and night safari, pinioning is never performed by the parks, only feather-clipping.
Personally i guess the population of flamingos on the lake to be 700 or so.
@chlidonias:
Wow, its a rare book you've got there! Is it still in good condition?
@JOn:
I have that book too, but mine's tattered already.