Cobb's Wrens with White Feathering

I was at Carcass Island on 25th February home to a large population of Cobb’s Wrens.

 

There seemed to be a lot of birds with white feathering in their plumage below are 3 of the 7 birds that I noted this in

 

A normal plumaged bird

A bird with a small amount of white feathers under the bill

A bird with a white central tail feather and greater covert feather also white feathering around the face.

A bird with 2 white primaries and single tertial feather also white feathering around face.