Redshanks and a mallard

I was at the Peedie Sea, the lagoon in the town, looking for a couple of birds- a black duck and a Bonaparte's gull. Found neither. The black duck is American and often hybridises with mallard so the reported bird may have been one of those and difficult to distinguish from the mallards. The 'Bony' looks a lot like black-headed gulls (to me) and I could not pick it out from the bhgs, if it was there at all. These redshanks were roosting on a boom and being very reflective.