The main bird entertainment during my visit there was a very lively population of Common Terns. I like the picture below because you can see the bird's tongue, but while initially you see the bird sitting on the post and happily snap away, loving that blurry bokeh background, the 'bird in flight' obsession soon overtakes you.
Manual or Shutter Priority is needed, and since at 1/2000th of a second I know I will be shooting wide open (here f4.5), they're pretty much the same thing while my Auto ISO will be the variable that hopefully correctly exposes the frame.
The shutter too is set to continuous burst mode at 6fps. And I'm all set to go.
Depth of field was razor thin so at least it had that much in common with a macro lens, and shutter speed still needs to be super high to avoid camera shake. All those problems aside, the pictures came out quite well. It's not something I would necessarily recommend, but experimenting with photography is how you learn.
London's other Wetlands Centre which is much bigger is in Barnes, but if like me East London is closer to you, Greenwich Ecology Park is a wonderful little place and I'm sure to go back, perhaps next time exclusively with a macro lens. I'll let you know how it works out.