I posted a couple of pics of a GSW with strange plumage a while back, consensus was it was a female with either Leucism or Erythrism. This is her offspring... as you can see, no plumage abnormalities are visible. The condition is inherited, so either it skipped a generation or it will show after post-juvenile moult. Through the double glazing and poor light early in the morning.
(I did post different pics in the main forum, but apart from @Kits, not much interest shown. This pic is a bit better, so adding to my gallery)
Camera Maker: SONY
Camera Model: SLT-A58
Lens: 75-300mm F4.5-5.6
Image Date: 2017-07-15 06:24:37 (no TZ)
Focal Length: 300.0mm (35mm equivalent: 450mm)
Aperture: /5.6
Exposure Time: 0.040 s (1/25)
ISO equiv: 800
Exposure Bias: -1.00 EV
Metering Mode: Matrix
Exposure: aperture priority (semi-auto)
White Balance: Auto
Flash Fired: No (enforced)
Orientation: Normal
Color Space: sRGB
GPS Coordinate: undefined, undefined
Copyright: 2017 Chris K