Six simple rephrasings
The snowy owl blends in with the snow because it is white.
Its white feathers help the snowy owl stay hidden on the snowy ground.
The white color of a snowy owl makes it hard to see in the snow.
On all that white snow, a snowy owl can be difficult to spot.
Snowy owls are tough to notice when everything is white and snowy.
Because it is white, the snowy owl can hide well against the snow.