BirdingNZ.net

The counts from the Lake Wairarapa (Eastern shoreline) wader survey conducted July 5th were:

268 NZ dabchick

39 Black shag

17 Little black shag

14 White-faced heron

1 Cattle egret

13 Royal spoonbill

1 Mute swan

3190 Black swan

945 Canada goose

83 Feral goose

16 Paradise shelduck

6 SI pied oystercatcher

3 Variable oystercatcher

969 Pied stilt

148 Banded dotterel

47 Black-fronted dotterel

29 Spur-winged plover

94 Black-backed gull

16 Red-billed gull

781 Black-billed gull
This high Black-billed gull count is interesting as it appears we have an influx of birds from other areas at the moment. We have a small resident colony which nests on the Ruamahanga River near Masterton - or, as happened last season - on the shoreline of the lake itself.
Cheers
Joanna

I suspect that the mute swan came from the Henley Lake flock (which, to my understanding, is dying out).
Are red-bills still considered a rarely-sighted species at the lake?

Yes I imagine you are right re the swans - I see the odd one here and there (such as the Masterton WWTP) which probably come from Henley Lake. I have never seen juveniles or immature mute swans at Henley so I think they must be declining, as you say.
The RBGs are seldom seen at Lake Wairarapa.