The first bird showed up with a companion (identically coloured) and started to harass several Caspian Terns which were soaring and diving at the end of the Jetty. The two interlopers seemed slightly larger than the Terns, but were very agile, making abrupt turns and even diving themselves (but I didn't see them go below the surface). One did grab a fish from somewhere.
The second bird landed right by the shore (at low tide) at the end of the Jetty. It looks like a cross between a Phalarope and a Bonaparte's. The mark on the head seems lower than a Bonaparte's would have for a full hood. Also, it has some odd markings on its wings. The top of the head is a rufous brown.
There are a couple of additional photos on the Flickr page.