The Silver Gull (known as the Red-billed Gull to us New Zealanders) is a small gull in the Masked Gulls genus.

Silver Gulls can be found across Australia, New Zealand and New Caledonia.
However the Red-billed Gull subspecies of New Zealand is nationally threated and on a serious and concerning decline.

Like other gulls, the Silver Gull mates for life and nests in dense breeding colonies.
In NZ there are more female Red-billed Gulls than males, so in some colonies there are female:female pairings, which surprisingly do better on average at raring young than hetero pairs.

These birds feed on small fish, krill, worms and other invertebrates.
Krill are essential to a successful breeding season and you will often see parent birds regurgitating krill for their young to feed on.

An interesting behaviour of these gulls is their "tap dance". Where they repeatedly stomp on grass on in puddles to mimic the vibrations of rain, which draws worms to the surface for them to feed on.